Head Injury and Risk of Incident Ischemic Stroke in Community-Dwelling Adults.

BACKGROUND: While stroke is a recognized short-term sequela of traumatic brain injury, evidence about long-term ischemic stroke risk after traumatic brain injury remains limited. METHODS: The Atherosclerosis Risk in Communities Study is an ongoing prospective cohort comprised of US community-dwelling adults enrolled in 1987 to 1989 followed through 2019. Head injury was defined using self-report and hospital-based diagnostic codes and was analyzed as a time-varying exposure. Incident ischemic stroke events were physician-adjudicated. We used Cox regression adjusted for sociodemographic and cardiovascular risk factors to estimate the hazard of ischemic stroke as a function of head injury. Secondary analyses explored the number and severity of head injuries; the mechanism and severity of incident ischemic stroke; and heterogeneity within subgroups defined by race, sex, and age. RESULTS: Our analysis included 12 813 participants with no prior head injury or stroke. The median follow-up age was 27.1 years (25th-75th percentile=21.1-30.5). Participants were of median age 54 years (25th-75th percentile=49-59) at baseline; 57.7% were female and 27.8% were Black. There were 2158 (16.8%) participants with at least 1 head injury and 1141 (8.9%) participants with an incident ischemic stroke during follow-up. For those with head injuries, the median age to ischemic stroke was 7.5 years (25th-75th percentile=2.2-14.0). In adjusted models, head injury was associated with an increased hazard of incident ischemic stroke (hazard ratio [HR], 1.34 [95% CI, 1.12-1.60]). We observed evidence of dose-response for the number of head injuries (1: HR, 1.16 [95% CI, 0.97-1.40]; ≥2: HR, 1.94 [95% CI, 1.39-2.71]) but not for injury severity. We observed evidence of stronger associations between head injury and more severe stroke (National Institutes of Health Stroke Scale score ≤5: HR, 1.31 [95% CI, 1.04-1.64]; National Institutes of Health Stroke Scale score 6-10: HR, 1.64 [95% CI, 1.06-2.52]; National Institutes of Health Stroke Scale score ≥11: HR, 1.80 [95% CI, 1.18-2.76]). Results were similar across stroke mechanism and within strata of race, sex, and age. CONCLUSIONS: In this community-based cohort, head injury was associated with subsequent ischemic stroke. These results suggest the importance of public health interventions aimed at preventing head injuries and primary stroke prevention among individuals with prior traumatic brain injuries.

Sex differences in the extent of acute axonal pathologies after experimental concussion.

Although human females appear be at a higher risk of concussion and suffer worse outcomes than males, underlying mechanisms remain unclear. With increasing recognition that damage to white matter axons is a key pathologic substrate of concussion, we used a clinically relevant swine model of concussion to explore potential sex differences in the extent of axonal pathologies. At 24 h post-injury, female swine displayed a greater number of swollen axonal profiles and more widespread loss of axonal sodium channels than males. Axon degeneration for both sexes appeared to be related to individual axon architecture, reflected by a selective loss of small caliber axons after concussion. However, female brains had a higher percentage of small caliber axons, leading to more extensive axon loss after injury compared to males. Accordingly, sexual dimorphism in axonal size is associated with more extensive axonal pathology in females after concussion, which may contribute to worse outcomes.

Timing of Cognitive Test Score Decline Prior to Incident Dementia Diagnosis in Blacks and Whites: The Atherosclerosis Risk in Communities Neurocognitive Study.

INTRODUCTION: Commonly occurring dementias include those of Alzheimer's, vascular, and mixtures of these and other pathologies. They are believed to evolve over many years, but that time interval has been difficult to establish. Our objective was to determine how many years in advance of a dementia diagnosis cognitive scores begin to change. METHODS: 14,086 dementia-free ARIC participants underwent a cognitive exam at baseline visit 2 (1990-1992, mean age 57 ± 5.72), and 11,244 at visit 4 (1996-1998), 5,640 at visit 5 (2011-2013), and 3,574 at visit 6 (2016-2017) with surveillance for dementias of all-causes combined. Within 5-year intervals after each visit, we compared performance on the Delayed Word Recall Test (DWRT), the Digit Symbol Substitution Test (DSST), the Word Fluency Test (WFT), and the combined mean of three cognitive tests at baseline in participants who were diagnosed with dementia within each interval versus those who survived the interval without a dementia diagnosis. Z-scores were adjusted for demographics and education in separate regression models for each visit. We plotted adjusted z-score means by time interval following each visit. RESULTS: During follow-up 3,334, 2,821, 1,218, and 329 dementia cases were ascertained after visits 2, 4, 5, and 6, respectively. Adjusted DWRT z-scores were significantly lower 20-25 years before dementia than those who did not experience dementia within 25 years. DSST z-scores were significantly lower at 25-30 years and 3-test combination z-scores were significantly lower as early as 30-31 years before onset. The difference between dementia and non-dementia group in the visit 2 3-test combination z-score was -0.20 at 30-31 years prior to dementia diagnosis. As expected, differences between the dementia and non-dementia groups increased closer to the time of dementia occurrence, up to their widest point at 0-5 years prior to dementia diagnosis. The difference between dementia and non-dementia groups in the visit 2 3-test combination z-score at 0-5 years was -0.90. WFT z-score differences were smaller than for the DSST or DWRT and began later. Patterns were similar in Black and White participants. CONCLUSION: DWRT, DSST, and combined 3-test z-scores were significantly lower more than 20 years prior to diagnosis in the dementia group versus the non-dementia group. Findings contribute to our knowledge of the long prodromal period in Blacks and Whites.

Occupation, Retirement Age, and 20-Year Cognitive Decline: The Atherosclerosis Risk in Communities Neurocognitive Study.

INTRODUCTION: We examined the association of both midlife occupation and age at retirement with cognitive decline in the Atherosclerosis Risk in Communities (ARIC) biracial community-based cohort. METHODS: Current or most recent occupation at ARIC baseline (1987-89; ages 45-64y) was categorized based on 1980 US census major occupation groups and tertiles of the Nam-Powers-Boyd occupational status score (n=14,090). Retirement status via annual follow-up questionnaires administered ascertained in 1999-2007 was classified as occurring before or after age 70 (n=7,503). Generalized estimating equation models were used to examine associations of occupation and age at retirement with trajectories of global cognitive factor scores, assessed from visit 2 (1990-92) to visit 5 (2011-2013). Models were a priori stratified by race and sex and adjusted for demographics and comorbidities. RESULTS: Low occupational status and blue-collar occupations were associated with low baseline cognitive scores in all race-sex strata. Low occupational status and homemaker status were associated with faster decline in White women but slower decline in Black women compared to high occupational status. Retirement before age 70 was associated with slower cognitive decline in White men and women and in Black men. Results did not change substantially after accounting for attrition. CONCLUSION: Low occupational status was associated with cognitive decline in women but not in men. Earlier retirement was associated with a slower cognitive decline in White participants and in Black men. Further research should explore reasons for the observed associations and race-sex differences.

Association of Win-Loss Record With Neuropsychiatric Symptoms and Brain Health Among Professional Fighters.

OBJECTIVE: Repetitive head impacts in professional fighting commonly lead to head injuries. Increased exposure to repetitive head trauma, measured by the number of professional fights and years of fighting, has been associated with slower processing speed and smaller brain volumes. The impact of win-loss outcomes has been investigated in other sports, with several studies suggesting that individuals on losing teams experience more head injuries. Here, the authors hypothesized that fighters with a worse fight record would exhibit poorer brain health outcomes. METHODS: The Professional Fighters Brain Health Study examined changes in neuropsychiatric symptoms, regional brain volume, and cognition among professional boxers and mixed martial arts fighters. These data were used to evaluate the relationship between win-loss ratios and brain health outcomes among professional fighters (N=212) by using validated neuropsychiatric symptom and cognitive measures and MRI data. RESULTS: Retired fighters with a better record demonstrated more impulsiveness (B=0.21, df=48) and slower processing speed (B=-0.42, df=31). More successful fighters did not perform better than fighters with worse records on any neuropsychiatric or cognitive test. Retired fighters with better fight records had smaller brain volumes in the subcortical gray matter, anterior corpus callosum, left and right hippocampi, left and right amygdala, and left thalamus. More successful active fighters had a smaller left amygdala volume. CONCLUSIONS: These findings suggest that among retired fighters, a better fight record was associated with greater impulsiveness, slower processing speed, and smaller brain volume in certain regions. This study shows that even successful fighters experience adverse effects on brain health.

Associations of Prior Head Injury With Mild Behavioral Impairment Domains.

OBJECTIVE: This study investigated associations of prior head injury and number of prior head injuries with mild behavioral impairment (MBI) domains. SETTING: The Atherosclerosis Risk in Communities (ARIC) Study. PARTICIPANTS: A total of 2534 community-dwelling older adults who took part in the ARIC Neurocognitive Study stage 2 examination were included. DESIGN: This was a prospective cohort study. Head injury was defined using self-reported and International Classification of Diseases, Ninth Revision ( ICD -9) code data. MBI domains were defined using the Neuropsychiatric Inventory Questionnaire (NPI-Q) via an established algorithm mapping noncognitive neuropsychiatric symptoms to the 6 domains of decreased motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, and abnormal perception/thought content. MAIN MEASURES: The primary outcome was the presence of impairment in MBI domains. RESULTS: Participants were a mean age of 76 years, with a median time from first head injury to NPI-Q administration of 32 years. The age-adjusted prevalence of symptoms in any 1+ MBI domains was significantly higher among individuals with versus without prior head injury (31.3% vs 26.0%, P = .027). In adjusted models, a history of 2+ head injuries, but not 1 prior head injury, was associated with increased odds of impairment in affective dysregulation and impulse dyscontrol domains, compared with no history of head injury (odds ratio [OR] = 1.83, 95% CI = 1.13-2.98, and OR = 1.74, 95% CI = 1.08-2.78, respectively). Prior head injury was not associated with symptoms in MBI domains of decreased motivation, social inappropriateness, and abnormal perception/thought content (all P > .05). CONCLUSION: Prior head injury in older adults was associated with greater MBI domain symptoms, specifically affective dysregulation and impulse dyscontrol. Our results suggest that the construct of MBI can be used to systematically examine the noncognitive neuropsychiatric sequelae of head injury; further studies are needed to examine whether the systematic identification and rapid treatment of neuropsychiatric symptoms after head injury is associated with improved outcomes.

Traumatic brain injury and cognitive change over 30 years among community-dwelling older adults.

INTRODUCTION: There is limited evidence regarding the rate of long-term cognitive decline after traumatic brain injury (TBI) among older adults. METHODS: In this prospective cohort study, time-varying TBI was defined by self-report and International Classification of Disease diagnostic codes. Cognitive testing was performed at five visits over 30 years and scores were combined into a global cognition factor score. Adjusted linear mixed-effects models estimated the association of TBI with cognitive change. RESULTS: A total of 11,701 Atherosclerosis Risk in Communities (ARIC) Study participants (mean baseline age 58 years, 58% female, 25% Black) without TBI at baseline were included. Over follow-up, 18% experienced TBI. The adjusted average decline in cognition per decade (standard deviation units) was more than twice as fast among individuals with ≥ 2 incident TBIs (𝛽 = -0.158, 95% confidence interval [CI] = -0.253,-0.063), but not among individuals with 1 TBI (𝛽 = -0.052, 95% CI = -0.107, 0.002), compared to without TBI (𝛽 = -0.057, 95% CI = -0.095, -0.020). DISCUSSION: This study provides robust evidence that TBIs fundamentally alter the trajectories of cognitive decline. HIGHLIGHTS: The adjusted average decline in cognition per decade (standard deviation units) was more than twice as fast among individuals with ≥ 2 incident traumatic brain injuries (TBIs; 𝛽 = -0.158, 95% confidence interval [CI] = -0.253, -0.063), but not with 1 TBI (𝛽 = -0.052, 95% CI = -0.107, 0.002), compared to without TBI (𝛽 = -0.057, 95% CI = -0.095, -0.020). Over a period of 30 years, this difference in cognitive decline is equivalent to individuals with ≥ 2 TBIs being 9.7 years older at baseline. Associations of TBI were stronger among individuals with one or two apolipoprotein E (APOE) ε4 alleles than among individuals with zero APOE ε4 alleles (P interaction = 0.007).

Traumatic Brain Injury and Long-Term Risk of Stroke Among US Military Veterans.

BACKGROUND: Traumatic brain injury (TBI) is associated with significant morbidity, but the association of TBI with long-term stroke risk in diverse populations remains less clear. Our objective was to examine the long-term associations of TBI with stroke and to investigate potential differences by age, sex, race and ethnicity, and time since TBI diagnosis. METHODS: Retrospective cohort study of US military veterans aged 18+ years receiving healthcare in the Veterans Health Administration system between October 1, 2002 and September 30, 2019. Veterans with TBI were matched 1:1 to veterans without TBI on age, sex, race and ethnicity, and index date, yielding 306 796 veterans with TBI and 306 796 veterans without TBI included in the study. In primary analyses, Fine-Gray proportional hazards models adjusted for sociodemographics and medical/psychiatric comorbidities were used to estimate the association between TBI and stroke risk, accounting for the competing risk of mortality. RESULTS: Participants were a mean age of 50 years, 9% were female, and 25% were of non-White race and ethnicity. Overall, 4.7% of veterans developed a stroke over a median follow-up of 5.2 years. Veterans with TBI had 1.69 times (95% CI, 1.64-1.73) increased risk of any stroke (ischemic or hemorrhagic) compared to veterans without TBI. This increased risk was highest in the first-year post-TBI diagnosis (hazard ratio [HR], 2.16 [95% CI, 2.03-2.29]) but remained elevated for 10+ years. Similar patterns were observed for secondary outcomes, with associations of TBI with hemorrhagic stroke (HR, 3.92 [95% CI, 3.59-4.29]) being stronger than with ischemic stroke (HR, 1.56 [95% CI, 1.52-1.61]). Veterans with both mild (HR, 1.47 [95% CI, 1.43-1.52]) and moderate/severe/penetrating injury (HR, 2.02 [95% CI, 1.96-2.09]) had increased risk of stroke compared to veterans without TBI. Associations of TBI with stroke were stronger among older compared to younger individuals (P interaction-by-age<0.001) and were weaker among Black veterans compared to other race and ethnicities (P interaction-by-race<0.001). CONCLUSIONS: Veterans with prior TBI are at increased long-term risk for stroke, suggesting they may be an important population to target for primary stroke prevention measures.

Trends and inequities in the diagnosis and treatment of poststroke depression: a retrospective cohort study of privately insured patients in the USA, 2003-2020.

BACKGROUND: Depression is a common neuropsychiatric consequence of stroke, but there is little empiric evidence regarding clinical diagnosis and management of poststroke depression. METHODS: Retrospective cohort study among 831 471 privately insured patients with first stroke in the USA from 2003 to 2020. We identified diagnoses of poststroke depression using codes from the International Classification of Diseases. We identified treatment based on prescriptions for antidepressants. We used Cox proportional hazards regression analysis to examine rates of poststroke depression diagnosis by gender, age and race/ethnicity. Among individuals who received a diagnosis of poststroke depression, we estimated treatment rates by gender, race/ethnicity and age using negative binomial regression analysis. RESULTS: Annual diagnosis and treatment rates for poststroke depression increased from 2003 to 2020 (both p for trend<0.001). Diagnosis rates were higher in women than men (HR 1.53, 95% CI 1.51 to 1.55), lower among members of racial/ethnic minorities (vs white patients: Asian HR 0.63, 95% CI 0.60 to 0.66; Black HR 0.76, 95% CI 0.74 to 0.78; Hispanic HR 0.88, 95% CI 0.86 to 0.90) and varied by age. Among individuals diagnosed with poststroke depression, 69.8% were prescribed an antidepressant. Rates of treatment were higher in women vs men (rate ratio, RR=1.19, 95% CI: 1.17 to 1.21), lower among members of racial/ethnic minorities (vs white patients: Asian RR 0.85, 95% CI 0.80 to 0.90; Black RR 0.92, 95% CI 0.89 to 0.94; Hispanic RR 0.96, 95% CI 0.93 to 0.99) and higher among older patients. CONCLUSIONS: In this insured population, we identify potential inequities in clinical management of poststroke depression by gender, race/ethnicity and age that may reflect barriers other than access to healthcare.

Wildfire smoke exposure and emergency department visits for headache: A case-crossover analysis in California, 2006-2020.

OBJECTIVE: To evaluate the association of short-term exposure to overall fine particulate matter of <2.5 µm (PM2.5 ) and wildfire-specific PM2.5 with emergency department (ED) visits for headache. BACKGROUND: Studies have reported associations between PM2.5 exposure and headache risk. As climate change drives longer and more intense wildfire seasons, wildfire PM2.5 may contribute to more frequent headaches. METHODS: Our study included adult Californian members (aged ≥18 years) of a large de-identified commercial and Medicare Advantage claims database from 2006 to 2020. We identified ED visits for primary headache disorders (subtypes: tension-type headache, migraine headache, cluster headache, and "other" primary headache). Claims included member age, sex, and residential zip code. We linked daily overall and wildfire-specific PM2.5 to residential zip code and conducted a time-stratified case-crossover analysis considering 7-day average PM2.5 concentrations, first for primary headache disorders combined, and then by headache subtype. RESULTS: Among 9898 unique individuals we identified 13,623 ED encounters for primary headache disorders. Migraine was the most frequently diagnosed headache (N = 5534/13,623 [47.6%]) followed by "other" primary headache (N = 6489/13,623 [40.6%]). For all primary headache ED diagnoses, we observed an association of 7-day average wildfire PM2.5 (odds ratio [OR] 1.17, 95% confidence interval [CI] 0.95-1.44 per 10 µg/m3 increase) and by subtype we observed increased odds of ED visits associated with 7-day average wildfire PM2.5 for tension-type headache (OR 1.42, 95% CI 0.91-2.22), "other" primary headache (OR 1.40, 95% CI 0.96-2.05), and cluster headache (OR 1.29, 95% CI 0.71-2.35), although these findings were not statistically significant under traditional null hypothesis testing. Overall PM2.5 was associated with tension-type headache (OR 1.29, 95% CI 1.03-1.62), but not migraine, cluster, or "other" primary headaches. CONCLUSIONS: Although imprecise, these results suggest short-term wildfire PM2.5 exposure may be associated with ED visits for headache. Patients, healthcare providers, and systems may need to respond to increased headache-related healthcare needs in the wake of wildfires and on poor air quality days.

Associations of Preexisting Vascular Risk Factors With Outcomes After Traumatic Brain Injury: A TRACK-TBI Study.

OBJECTIVE: To evaluate associations of preinjury vascular risk factors with traumatic brain injury (TBI) outcomes. SETTING: The level 1 trauma center-based T ransforming R esearch a nd C linical K nowledge in TBI (TRACK-TBI) Study. PARTICIPANTS: A total of 2361 acute TBI patients 18 years or older who presented to the emergency department within 24 hours of head trauma warranting clinical evaluation with a noncontrast head CT between February 26, 2014, and August 8, 2018. DESIGN: A multicenter prospective cohort study. MAIN MEASURES: Vascular risk factors (hypertension, diabetes, hyperlipidemia, and smoking) were assessed at baseline by self- or proxy-report and chart review. The primary outcome was the 6-month Glasgow Outcome Scale-Extended TBI version (GOSE-TBI). Secondary 6-month outcomes included the Rivermead Post-Concussion Symptoms Questionnaire (RPQ), the Satisfaction with Life Scale (SWLS), and the 18-item Brief Symptom Inventory Global Severity Index (BSI-18-GSI). RESULTS: Mean age of participants was 42 years, 31% were women, and 16% were Black. Current smoking was the most common vascular risk factor (29%), followed by hypertension (17%), diabetes (8%), and hyperlipidemia (6%). Smoking was the only risk factor associated with worse scores on all 4 outcome indices. Hypertension and diabetes were associated with worse RPQ scores, and hypertension was associated with worse BSI-18-GSI scores (all P < .05). Compared with individuals with no vascular risk factors, individuals with 1 but not 2 or more vascular risk factors had significantly worse GOSE-TBI and SWLS scores, while a higher burden of vascular risk factors was significantly associated with worse RPQ and BSI-18-GSI scores. CONCLUSION: Our study found that preinjury vascular risk factors, especially smoking, are associated with worse outcomes after TBI. Aggressive postinjury treatment of vascular risk factors may be a promising strategy to improve TBI outcomes.

Olfactory Dysfunction Following Moderate to Severe Traumatic Brain Injury: A Systematic Review and Meta-Analysis.

OBJECTIVE: Reports of smell loss following traumatic brain injury (TBI) are a well-documented but understudied phenomenon. Given the broad consequences of olfactory loss, we characterized psychophysical olfactory dysfunction in individuals with moderate to severe TBI using systematic review and meta-analytic methods. METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) protocol, five databases (PubMed, EMBASE, Cochrane Library, Web of Science, Scopus) were reviewed for studies investigating olfactory dysfunction in persons with moderate to severe TBI. Of the 5,223 studies reviewed, 19 met our inclusion criteria for the systematic review and 11 met inclusion criteria for meta-analysis. We calculated effect sizes (Hedges' g) to characterize the degree of olfactory dysfunction between patients with moderate to severe TBI and controls. RESULTS: A total of 951 moderate-severe TBI patients from 19 studies were included in the systematic review, which largely demonstrated poorer olfactory psychophysical performances in this patient population. Meta-analysis demonstrated a large effect size for olfactory dysfunction in moderate-severe TBI relative to healthy controls (g=-2.43, 95%CI: -3.16 < δ<-1.69). The magnitude of the effect was moderated by age and patient sex, with larger effect sizes associated with older age (following exclusion of a pediatric population) and larger compositions of women in the patient group. CONCLUSION: Moderate to severe TBI is associated with prominent olfactory dysfunction. Significant research gaps remain regarding the mechanism, recovery and natural history of olfactory dysfunction following moderate to severe TBI, which has significant clinical implications for the identification and treatment for those with post-traumatic olfactory dysfunction.

Brain Imaging Features Associated with 20-Year Cognitive Decline in a Community-Based Multiethnic Cohort without Dementia.

INTRODUCTION: This study aimed to characterize the association of cognitive decline starting in midlife with brain pathology in late life in the absence of dementia. METHODS: Nondemented Atherosclerosis Risk in Communities participants with brain imaging, all cognitive factor scores (CFSs), and nonmissing covariates were included. CFSs were collected at three visits across 21 years (1990-2013) (short-term cognitive change [1990-1996], long-term cognitive change [1990-2013]), and brain magnetic resonance imaging and florbetapir positron emission tomography (PET) imaging were collected in 2011-13 (PET subset n = 327). Outcomes of interest were total and regional brain volumes (cm3), log2 (white matter hyperintensity volume), white matter integrity (fractional anisotropy, mean diffusivity), ≥1 lacunar infarct (3-20 mm), and elevated brain ß-amyloid (SUVR >1.2). Multivariable linear/logistic regression related outcomes to CFS slopes after adjusting for demographics and total intracranial volume. RESULTS: At baseline, the 1,734 participants had a mean (SD) age of 55 (5.2) years, and were 60% female and 26% Black. After adjustment, a 1-SD larger long-term decline in CFS was associated with a smaller relative total brain volume by 1.2% (95% CI: 1.0, 1.5), a smaller relative temporal lobe meta region volume by 1.9% (1.5, 2.3), a 13% (9, 17) larger volume of white matter hyperintensities, a 1.3-fold (1.2, 1.4) higher odds of having ≥1 lacune, and 1.7-fold (1.3, 2.2) higher odds of elevated brain ß-amyloid deposition and worse white matter integrity. Some long-term associations were also found for midlife short-term declines in CFS. CONCLUSIONS: This study provides evidence that starting in midlife, short-term and long-term declines in cognition are associated with multiple deleterious late-life differences in nondemented brains.

Associations of Peripheral Neuropathy Defined by Monofilament Insensitivity with Mild Cognitive Impairment and Dementia in Older Adults.

INTRODUCTION: The aim of this study was to assess the association of peripheral neuropathy (PN) as defined by monofilament insensitivity with mild cognitive impairment (MCI) and dementia in older adults with and without diabetes. METHODS: We conducted a cross-sectional analysis of 3,362 Black and White participants in the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS) who underwent monofilament testing at visit 6 (2016-2017, age 71-94 years). Participants' cognitive status was classified by an adjudication committee as cognitively normal, MCI, or dementia after completing a comprehensive battery of neurocognitive assessments. We used logistic regression to evaluate the association of PN with MCI or dementia overall and stratified by diabetes status after adjusting for traditional dementia risk factors. We also compared age-adjusted brain MRI measures among a subset (N = 1,095) of participants with versus without PN. RESULTS: Overall, the prevalence of MCI (21.9% vs. 16.7%) and dementia (7.8% vs. 3.9%) were higher among participants with versus without PN (both p < 0.05). After adjustment, PN was positively associated with MCI or dementia in the overall study population (OR 1.45, 95% CI 1.23, 1.73). Results were similar by diabetes status (diabetes: OR 1.38, 95% CI 1.03-1.87; no diabetes: OR 1.48, 95% CI 1.20-1.83; p-for-interaction = 0.46). Age-adjusted total and lobar brain volumes were significantly lower in participants with versus without PN (both, p < 0.05). DISCUSSION/CONCLUSIONS: PN as defined by monofilament insensitivity was associated with cognitive status independent of vascular risk factors and regardless of diabetes status. Our findings support a connection between PN and cognitive impairment, even in the absence of diabetes.

Head injury and 25-year risk of dementia.

INTRODUCTION: Head injury is associated with significant morbidity and mortality. Long-term associations of head injury with dementia in community-based populations are less clear. METHODS: Prospective cohort study of 14,376 participants (mean age 54 years at baseline, 56% female, 27% Black, 24% with head injury) enrolled in the Atherosclerosis Risk in Communities (ARIC) Study. Head injury was defined using self-report and International Classification of Diseases, Ninth/Tenth Revision (ICD-9/10) codes. Dementia was defined using cognitive assessments, informant interviews, and ICD-9/10 and death certificate codes. RESULTS: Head injury was associated with risk of dementia (hazard ratio [HR] = 1.44, 95% confidence interval [CI] = 1.3-1.57), with evidence of dose-response (1 head injury: HR = 1.25, 95% CI = 1.13-1.39, 2+ head injuries: HR = 2.14, 95% CI = 1.86-2.46). There was evidence for stronger associations among female participants (HR = 1.69, 95% CI = 1.51-1.90) versus male participants (HR = 1.15, 95% CI = 1.00-1.32), P-for-interaction < .001, and among White participants (HR = 1.55, 95% CI = 1.40-1.72) versus Black participants (HR = 1.22, 95% CI = 1.02-1.45), P-for-interaction = .008. DISCUSSION: In this community-based cohort with 25-year follow-up, head injury was associated with increased dementia risk in a dose-dependent manner, with stronger associations among female participants and White participants.

Microvascular Brain Disease Progression and Risk of Stroke: The ARIC Study.

BACKGROUND AND PURPOSE: Data on the significance of combined white matter hyperintensities (WMH)/lacunar brain infarcts, and their progression over time for the prediction of stroke are scarce. We studied associations between the progression in combined measures of microvascular brain disease and risk of stroke in the ARIC study (Atherosclerosis Risk in Communities). METHODS: Prospective analysis of 907 stroke-free ARIC participants who underwent a brain magnetic resonance imaging (MRI) in 1993 to 1995, a second brain MRI in 2004 to 2006, and were subsequently followed for stroke incidence through December 31, 2017 (median [25%-75%] follow-up 12.6 [8.9-13.4] years). A combined measure of microvascular brain disease was defined at each visit and categorized by progression from first to second brain MRI as no progression; mild progression (increase of ≥1 unit in WMH grade or new lacune), and moderate progression (increase of ≥1 unit in WMH grade and new lacune). All definite/probable ischemic or hemorrhagic incident strokes occurring after this second MRI, and through 2017, were included. Associations between microvascular brain disease, progression in the combined measures, and stroke incidence were studied with Cox proportional hazard models, adjusting for age, sex, race, education level, time from first to second MRI, body mass index, smoking, hypertension, diabetes mellitus, and coronary heart disease. RESULTS: At the second brain MRI (mean age 72), the distribution of the combined measure was 37% WMH grade <2 and no lacune; 57% WMH grade ≥2 or lacune; and 6% WMH grade ≥2 and lacune. No progression in the combined measures was observed in 38% of participants, 57% showed mild progression and 5% showed moderate progression. Sixty-four incident strokes occurred during the follow-up period. Compared with no change in the combined measure, moderate progression of microvascular brain disease was significantly associated with higher risk of stroke (adjusted hazard ratio, 3.00 [95% CI, 1.30-6.94]). CONCLUSIONS: Progression of microvascular brain disease, manifesting as both new lacunes and increase in WMHs grade, is related to substantial increase in long-term risk of stroke.

Mid-life serum Vitamin D concentrations were associated with incident dementia but not late-life neuropsychological performance in the Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND: Activated Vitamin D has anti-inflammatory properties and adequate 25-hydroxyvitamin D [25(OH)D] concentrations may be important for neurocognitive function and protection against neurologic injury. We examined whether mid-life 25(OH) D concentrations were associated with later-life performance on neuropsychological testing, functional ability, depressive symptoms, and incident dementia. METHODS: We studied 13,039 white and black ARIC participants who had serum 25(OH) D measured mid-life at visit 2 (1990-1992). Over the next ~ 20 years through visit 5 (2011-2013), participants underwent 3 additional in-person visits, annual telephone calls, and hospitalization surveillance. An extensive battery of neuropsychological outcomes were assessed at visit 5 using standardized protocols. Incident dementia was ascertained through a formal algorithm that included data from in-person cognitive testing, telephone interviews, hospital discharge codes, and death certificate codes. Diagnoses of dementia were adjudicated by expert clinician committee. For the primary cognitive analyses, we imputed for missing covariates and outcomes and used linear regression to evaluate non-concurrent cross-sectional associations of mid-life 25(OH) D (visit 2) with late-life neuropsychological outcomes (visit 5). We also used Cox regression models to examine associations of mid-life 25(OH) D and incident dementia. RESULTS: In mid-life, the mean (SD) age of participants was 57 (6) years, 57% were women, and 24% black. Mean (SD) 25(OH) D was 24.3 (8.6) ng/mL; 33% had deficient (< 20 ng/mL), 44% intermediate (20- < 30 ng/mL), and 23% sufficient (≥30 ng/mL) 25(OH) D concentrations. Association between mid-life 25(OH) D and late-life performance on neuropsychological testing were mostly null. There was no significant association with functional ability or depressive symptoms. Results were similar in a sensitivity analysis using complete-case data (no imputation). However, after a median follow-up of 20 years, low 25(OH) D concentrations were associated with increased risk for incident dementia (p = 0.01 for trend across categories), with HR of 1.26 (95% CI 1.06, 1.49) for participants with deficient 25(OH) D, compared to sufficient concentrations. CONCLUSION: In this community cohort, mid-life serum 25(OH) D concentrations were associated with incident dementia but not with performance on neuropsychological testing, functional ability, or depressive symptoms, 20 years later. Whether serum 25(OH) D concentrations are causally related to dementia or confounded by poorer health status remains uncertain. TRIAL REGISTRATION: Registered on clinicaltrials.gov NCT00005131 .

Association of Midlife to Late-Life Blood Pressure Patterns With Incident Dementia.

Importance: The association between late-life blood pressure (BP) and cognition may depend on the presence and chronicity of past hypertension. Late-life declines in blood pressure following prolonged hypertension may be associated with poor cognitive outcomes. Objective: To examine the association of midlife to late-life BP patterns with subsequent dementia, mild cognitive impairment, and cognitive decline. Design, Setting, and Participants: The Atherosclerosis Risk in Communities prospective population-based cohort study enrolled 4761 participants during midlife (visit 1, 1987-1989) and followed-up over 6 visits through 2016-2017 (visit 6). BP was examined over 24 years at 5 in-person visits between visits 1 and 5 (2011-2013). During visits 5 and 6, participants underwent detailed neurocognitive evaluation. The setting was 4 US communities: Washington County, Maryland; Forsyth County, North Carolina; Jackson, Mississippi; and Minneapolis, Minnesota. Follow-up ended on December 31, 2017. Exposures: Five groups based on longitudinal patterns of normotension, hypertension (>140/90 mm Hg), and hypotension (<90/60 mm Hg) at visits 1 to 5. Main Outcomes and Measures: Primary outcome was dementia onset after visit 5, based on Ascertain Dementia-8 informant questionnaires, Six-Item Screener telephone assessments, hospital discharge and death certificate codes, and the visit 6 neurocognitive evaluation. Secondary outcome was mild cognitive impairment at visit 6, based on the neurocognitive evaluation. Results: Among 4761 participants (2821 [59%] women; 979 [21%] black race; visit 5 mean [SD] age, 75 [5] years; visit 1 mean age range, 44-66 years; visit 5 mean age range, 66-90 years), there were 516 (11%) incident dementia cases between visits 5 and 6. The dementia incidence rate for participants with normotension in midlife (n = 833) and late life was 1.31 (95% CI, 1.00-1.72 per 100 person-years); for midlife normotension and late-life hypertension (n = 1559), 1.99 (95% CI, 1.69-2.32 per 100 person-years); for midlife and late-life hypertension (n = 1030), 2.83 (95% CI, 2.40-3.35 per 100 person-years); for midlife normotension and late-life hypotension (n = 927), 2.07 (95% CI, 1.68-2.54 per 100 person-years); and for midlife hypertension and late-life hypotension (n = 389), 4.26 (95% CI, 3.40-5.32 per 100 person-years). Participants in the midlife and late-life hypertension group (hazard ratio [HR], 1.49 [95% CI, 1.06-2.08]) and in the midlife hypertension and late-life hypotension group (HR, 1.62 [95% CI, 1.11-2.37]) had significantly increased risk of subsequent dementia compared with those who remained normotensive. Irrespective of late-life BP, sustained hypertension in midlife was associated with dementia risk (HR, 1.41 [95% CI, 1.17-1.71]). Compared with those who were normotensive in midlife and late life, only participants with midlife hypertension and late-life hypotension had higher risk of mild cognitive impairment (37 affected individuals (odds ratio, 1.65 [95% CI, 1.01-2.69]). There was no significant association of BP patterns with late-life cognitive change. Conclusions and Relevance: In this community-based cohort with long-term follow-up, sustained hypertension in midlife to late life and a pattern of midlife hypertension and late-life hypotension, compared with midlife and late-life normal BP, were associated with increased risk for subsequent dementia.

Serum Vitamin D Concentrations and Cognitive Change Over 20 Years: The Atherosclerosis Risk in Communities Neurocognitive Study.

BACKGROUND/AIMS: 25-hydroxyvitamin D (25[OH]D) concentrations have been associated with cognitive decline and incident dementia in elderly populations; however, these relationships are susceptible to reverse causation. Less is known about the association of midlife 25(OH)D with long-term cognitive decline. METHODS: This was a prospective cohort study of 13,044 participants (mean age 57 years at baseline) in the Atherosclerosis Risk in Communities Study. 25(OH)D was measured from serum collected at baseline (1990-1992) using liquid chromatography tandem high-sensitivity mass spectrometry. Cognition was assessed using 3 neuropsychological tests at 3 time points, which were combined into a composite cognitive Z-score. Multivariable-adjusted linear mixed-effects models with random intercepts and slopes were used to estimate associations between 25(OH)D and cognitive change over 20 years. RESULTS: Compared to persons with sufficient 25(OH)D (≥30 ng/mL), those with deficient (< 20 ng/mL) and intermediate (20-< 30 ng/mL) 25(OH)D concentrations had similar cognitive decline in composite cognitive Z-scores (deficient versus sufficient: -0.035 [95% CI -0.104 to 0.033] and intermediate versus sufficient: -0.029 [95% CI -0.080 to 0.023]). CONCLUSIONS: Lower concentrations of 25(OH)D measured in midlife were not significantly associated with more rapid cognitive decline over a 20-year follow-up period. The results of this prospective study are less susceptible to reverse causation than prior studies.

Midlife vascular risk factors and midlife cognitive status in relation to prevalence of mild cognitive impairment and dementia in later life: The Atherosclerosis Risk in Communities Study.

INTRODUCTION: The interplay between midlife vascular risk factors and midlife cognitive function with later life mild cognitive impairment (MCI) and dementia (DEM) is not well understood. METHODS: In the Atherosclerosis Risk in Communities Study, cardiovascular risk factors and cognition were assessed in midlife, ages 45-64 years. In 2011-2013, 20-25 years later, all consenting Atherosclerosis Risk in Communities participants underwent a cognitive and neurological evaluation and were given adjudicated diagnoses of cognitively normal, MCI, or DEM. RESULTS: In 5995 participants with complete covariate data, midlife diabetes, hypertension, obesity, and hypercholesterolemia were associated with late-life MCI and DEM. Low midlife cognition function was also associated with greater likelihood of late-life MCI or DEM. Both midlife vascular risk factors and midlife cognitive function remained associated with later life MCI or DEM when both were in the model. DISCUSSION: Later life MCI and DEM were independently associated with midlife vascular risk factors and midlife cognition.