Social Health and Cognitive Change in Old Age: Role of Brain Reserve.

OBJECTIVE: Individual aspects of social health (SH; eg, network, engagement, support) have been linked to cognitive health. However, their combined effect and the role of the structural properties of the brain (brain reserve [BR]) remain unclear. We investigated the interplay of SH and BR on cognitive change in older adults. METHODS: Within the Swedish National Study on Aging and Care-Kungsholmen, 368 dementia-free adults aged ≥60 years with baseline brain magnetic resonance imaging were followed over 12 years to assess cognitive change. A measure of global cognition was computed at each of the 5 waves of assessment by averaging domain-specific Z scores for episodic memory, perceptual speed, semantic memory, and letter and category fluency. An SH composite score was computed at baseline by combining leisure activities and social network. BR was proxied by total brain tissue volume (TBTV). Linear mixed models (adjusted for sociodemographic, vascular, and genetic factors) were used to estimate cognitive trajectories in relation to SH and TBTV. Interaction analysis and stratification were used to examine the interplay between SH and TBTV. RESULTS: Moderate-good SH (n = 245; vs poor, ß-slope = 0.01, 95% confidence interval [CI] = 0.002-0.02, p = 0.018) and moderate-to-large TBTV (n = 245; vs small, ß-slope = 0.03, 95% CI = 0.02-0.04, p < 0.001) were separately associated with slower cognitive decline. In stratified analysis, moderate-good SH was associated with higher cognitive levels (but not change) only in participants with moderate-to-large TBTV (ß-intercept = 0.21, 95% CI = 0.06-0.37, p < 0.01; interaction SH * TBTV, p < 0.05). INTERPRETATION: Our findings highlight the interplay between SH and BR that likely unfolds throughout the entire life course to shape old-age cognitive outcomes. ANN NEUROL 2023;93:844-855.

Change in cardiovascular health and rate of cognitive decline in older adults: a 15-year population-based study.

BACKGROUND: Previous research on associations between cardiovascular health, measured at a single timepoint, and rate of age-related cognitive decline shows divergent findings dependent on the participants' age and the health metric studied. The aim of this study was to add to the knowledge in this field by investigating whether change in cardiovascular health, assessed with Life's Simple 7 (LS7) score, is associated with rate of cognitive change in young-old and old-old adults. METHODS: The study included 1022 participants aged ≥ 60 years from the Swedish National Study on Aging and Care-Kungsholmen (SNAC-K), who underwent repeated neuropsychological testing (episodic memory, semantic memory, verbal fluency, and perceptual speed) across up to 15 years. LS7, composed of seven cardiovascular health metrics (smoking, diet, physical activity, body mass index, plasma glucose, total serum cholesterol, and blood pressure), was assessed at baseline and at the 6-year follow-up. Change in LS7 was calculated as the difference between baseline and 6 years (range - 5 to 8 points) and categorised into worse (-5 to -2 points), stable (-1 to 1 points), and improved (2 to 8 points). Change in cognitive performance as a function of LS7 change categories was estimated using linear mixed-effects models. RESULTS: Participants were classified as stable (67.1%), improved (21.0%), or worse (11.8%) according to changes in LS7 score. Both the worse and improved categories were associated with faster cognitive decline. Age-stratified analyses revealed that worsening of LS7 was clearly associated with faster cognitive decline in the old-old (≥ 78 years), whereas improvement tended be associated with faster cognitive decline in the young-old (< 78 years) group. CONCLUSIONS: Change in cardiovascular health in old age may lead to accelerated cognitive decline, particularly in late senescence. These results suggest that it is important to monitor and maintain cardiovascular health status in very old adults.

Association of cognitive reserve with transitions across cognitive states and death in older adults: A 15-year follow-up study.

INTRODUCTION: We investigated the association of cognitive reserve (CR) with transitions across cognitive states and death. METHODS: This population-based cohort study included 2631 participants (age ≥60 years) who were dementia-free at baseline and regularly examined up to 15 years. Data were analyzed using the Markov multistate models. RESULTS: Each 1-point increase in the composite CR score (range: -4.25 to 3.46) was significantly associated with lower risks of transition from normal cognition to cognitive impairment, no dementia (CIND) (multivariable-adjusted hazards ratio = 0.78; 95% confidence interval = 0.72-0.85) and death (0.85; 0.79-0.93), and from CIND to death (0.82; 0.73-0.91), but not from CIND to normal cognition or dementia. A greater composite CR score was associated with a lower risk of transition from CIND to death in people aged 60-72 but not in those aged ≥ 78 years. DISCUSSION: CR contributes to cognitive health by delaying cognitive deterioration in the prodromal phase of dementia. HIGHLIGHTS: We use Markov multistate model to examine the association between cognitive reserve and transitions across cognitive states and death. A great cognitive reserve contributes to cognitive health by delaying cognitive deterioration in the prodromal phase of dementia. A great cognitive reserve is associated with a lower risk of transition from cognitive impairment, no dementia to death in people at the early stage of old age, but not in those at the late stage of old age.

Association of mild and complex multimorbidity with structural brain changes in older adults: A population-based study.

INTRODUCTION: We quantified the association of mild (ie, involving one or two body systems) and complex (ie, involving ≥3 systems) multimorbidity with structural brain changes in older adults. METHODS: We included 390 dementia-free participants aged 60+ from the Swedish National Study on Aging and Care in Kungsholmen who underwent brain magnetic resonance imaging at baseline and after 3 and/or 6 years. Using linear mixed models, we estimated the association between multimorbidity and changes in total brain tissue, ventricular, hippocampal, and white matter hyperintensities volumes. RESULTS: Compared to non-multimorbid participants, those with complex multimorbidity showed the steepest reduction in total brain (ß*time -0.03, 95% CI -0.05, -0.01) and hippocampal (ß*time -0.05, 95% CI -0.08, -0.03) volumes, the greatest ventricular enlargement (ß*time 0.03, 95% CI 0.01, 0.05), and the fastest white matter hyperintensities accumulation (ß*time 0.04, 95% CI 0.01, 0.07). DISCUSSION: Multimorbidity, particularly when involving multiple body systems, is associated with accelerated structural brain changes, involving both neurodegeneration and vascular pathology. HIGHLIGHTS: Multimorbidity accelerates structural brain changes in cognitively intact older adults These brain changes encompass both neurodegeneration and cerebrovascular pathology The complexity of multimorbidity is associated with the rate of brain changes' progression.

Lung function in relation to brain aging and cognitive transitions in older adults: A population-based cohort study.

BACKGROUND: We investigated the association of peak expiratory flow (PEF) with dementia; cognitive impairment, no dementia (CIND); and transition from CIND to dementia, and possible underlying neuropathological mechanisms. METHODS: A population-based cohort of adults aged 60+ was followed over 15 years to detect dementia (Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria), CIND (assessed through a cognitive battery), and progression from CIND to dementia, in relation to baseline PEF observations. A subsample (n = 462) had 6-year follow-up data on brain magnetic resonance imaging markers of neurodegeneration and small vessel disease. RESULTS: In fully adjusted models, poor PEF performance (< 10th vs. ≥ 80th percentile) was associated with increased hazards for dementia (hazard ratio [HR] = 1.89; 95% confidence interval [CI] = 1.23-2.92) and CIND (HR = 1.55; 95% CI = 1.01-2.38) and CIND progression to dementia, although not statistically significantly (HR = 2.44; 95% CI = 0.78-6.88). People with poor PEF also experienced the fastest ventricular enlargement (ß coefficient = 0.67 mL/year; 95% CI = 0.13-1.21) and had the highest likelihood of developing lacunes (odds ratio = 5.05; 95% CI = 1.01-25.23). DISCUSSION: Poor lung function contributes to cognitive deterioration possibly through accelerated brain atrophy and microvascular damage. HIGHLIGHTS: Poor lung function increased the risk of dementia and mild cognitive impairment (MCI). Poor lung function accelerated the progression from MCI to dementia. Poor lung function was linked to brain microvascular damage and global brain atrophy.

The age-dependent association of Life's Simple 7 with transitions across cognitive states after age 60.

BACKGROUND: Life's Simple 7 (LS7) aims to promote ideal cardiovascular health (CVH). Its association with different cognitive states in the older old is unclear. OBJECTIVES: To assess the associations of LS7 with transitions across normal cognition, cognitive impairment, no dementia (CIND), and dementia and evaluate cognitive impairment-free years of life by LS7-defined CVH levels in older adults. METHODS: This cohort study included 2746 participants from the Swedish National Study on Aging and Care in Kungsholmen, regularly examined over 15 years. Total LS7 scores were created and dichotomized into worse and better CVH categories. The associations of LS7 total scores and CVH categories with cognitive states were assessed with multistate models in the whole sample and in younger old (<78 years) and older old adults (≥78 years) separately. Cognitive impairment-free life years by CVH categories were then predicted. RESULTS: A 1-point increment in the LS7 total score was associated with lower dementia risk in younger old adults (hazard ratio: 0.87 [0.78-0.97]) but not in older old adults (1.04 [0.97-1.13]). Better CVH was also associated with a lower risk of transition from normal cognition to CIND (0.76 [0.61-0.95]) and from normal cognition to dementia (0.42 [0.21-0.82]) in younger old adults. In younger old adults, those with better CVH were predicted to have two-to-three more cognitive impairment-free life years than those with worse CVH. CONCLUSION: Maintaining LS7-defined ideal CVH seems relevant in younger old adults but not in older old adults when considering the potential protective effects against cognitive impairment.

Multimorbidity patterns and 18-year transitions from normal cognition to dementia and death: A population-based study.

BACKGROUND: Several chronic diseases accelerate cognitive decline; however, it is still unknown how different patterns of multimorbidity influence individuals' trajectories across the cognitive continuum. OBJECTIVES: We aimed to investigate the impact of multimorbidity and of specific multimorbidity patterns on the transitions across cognitive stages (normal cognition, cognitive impairment, no dementia [CIND], dementia) and death. METHODS: We included 3122 dementia-free individuals from the Swedish National study on Aging and Care in Kungsholmen. Using fuzzy c-means cluster analysis, multimorbid participants were classified into mutually exclusive groups characterized by commonly coexisting chronic diseases. Participants were followed up to 18 years to detect incident CIND, dementia, or death. Transition hazard ratios (HRs), life expectancies, and time spent in different cognitive stages were estimated using multistate Markov models. RESULTS: At baseline, five multimorbidity patterns were identified: neuropsychiatric, cardiovascular, sensory impairment/cancer, respiratory/metabolic/musculoskeletal, and unspecific. Compared to the unspecific pattern, the neuropsychiatric and sensory impairment/cancer ones showed reduced hazards of reverting from CIND to normal cognition (HR 0.53, 95% CI 0.33-0.85 and HR 0.60, 95% CI 0.39-0.91). Participants in the cardiovascular pattern exhibited an increased hazard of progression from CIND to dementia (HR 1.70, 95% CI 1.15-2.52) and for all transitions to death. Subjects with the neuropsychiatric and cardiovascular patterns showed reduced life expectancy at age 75, with an anticipation of CIND (up to 1.6 and 2.2 years, respectively) and dementia onset (up to 1.8 and 3.3 years, respectively). CONCLUSIONS: Multimorbidity patterns differentially steer individual trajectories across the cognitive continuum of older adults and may be used as a risk stratification tool.

Markers of olfactory dysfunction and progression to dementia: A 12-year population-based study.

INTRODUCTION: We evaluated markers of olfactory dysfunction (OD) for estimating hazard of dementia in older adults. METHODS: Mild (hyposmia) and severe (anosmia) OD was classified in a population-based study of dementia-free persons (SNAC-K; n = 2473; mean age = 70 years) using the Sniffin sticks odor identification task. Combined variables were created for objective and subjective OD and for OD and APOE status. Hazard of dementia across 12 years was estimated with Cox regression. RESULTS: OD was associated with increased hazard of dementia (2.01; 95% confidence interval [CI] 1.60-2.52), with the strongest association for anosmia (2.92; 95% CI 2.14-3.98). Results remained consistent after adjusting for potential confounders and across age and sex subgroups. APOE ε4 carriers with anosmia had the highest hazard of dementia (ε4: 6.95; 95% CI 4.16-11.62; ε4/ε4: 19.84; 95% CI 6.17-63.78). DISCUSSION: OD is associated with increased risk of dementia, especially severe impairment in combination with genetic risk of Alzheimer's disease.

Association of ischemic heart disease with long-term risk of cognitive decline and dementia: A cohort study.

INTRODUCTION: The independent and joint effect of ischemic heart disease (IHD) and coexisting atrial fibrillation (AF) and heart failure (HF) on dementia risk is largely unknown. METHODS: This population-based cohort study included 2568 dementia-free participants (age ≥60 years) in SNAC-K, who were regularly examined from 2001-2004 through 2013-2016. Dementia was diagnosed following the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria. Global cognitive function was assessed using a global cognitive composite z-score derived from five cognitive domains. Data were analyzed using Cox, Fine-Gray, and linear mixed-effects models. RESULTS: Overall, IHD at baseline was associated with multivariable-adjusted hazard ratio (HR) of 1.39 (95% confidence interval = 1.06-1.82) for dementia and multivariable-adjusted ß-coefficient of -0.02 (-0.03 to -0.01) for annual changes in global cognitive z-score, independent of AF, HF, and cerebrovascular disease. Coexisting AF or HF did not add further risk to dementia and cognitive decline. DISCUSSION: IHD is independently associated with dementia and cognitive decline in older adults, whereas coexisting AF/HF is not associated with an increased risk. HIGHLIGHTS: Is a history of ischemic heart disease (IHD) associated with a risk for dementia? How do coexisting heart diseases affect this association? IHD was an independent risk factor for dementia in older adults. This association was independent of coexisting heart and cerebrovascular diseases. The coexistence of heart diseases did not confer additional risk for dementia.

A glycan epitope correlates with tau in serum and predicts progression to Alzheimer's disease in combination with APOE4 allele status.

INTRODUCTION: There is an urgent need for novel blood biomarkers for the detection of Alzheimer's disease (AD). We previously showed that levels of the bisecting N-acetylglucosamine glycan epitope was elevated in cerebrospinal fluid in AD. However, its diagnostic value in blood is unknown. METHODS: We analyzed blood levels of bisecting N-acetylglucosamine and total tau in a retrospective cohort of 233 individuals. Progression to AD was compared between the groups using Cox regression. The predictive value of the biomarkers was determined by logistic regression. RESULTS: Bisecting N-acetylglucosamine correlated with tau levels (p < 0.0001). Individuals with an intermediate tau/bisecting N-acetylglucosamine ratio had elevated AD risk (hazard ratio = 2.06, 95% confidence interval [CI]: 1.18-3.6). Moreover, a combined model including tau/bisecting N-acetylglucosamine ratio, apolipoprotein E (APOE) ε4 status, and Mini-Mental State Examination score predicted future AD (area under the curve = 0.81, 95% CI: 0.68-0.93). DISCUSSION: Bisecting N-acetylglucosamine in combination with tau is a valuable blood biomarker for predicting AD.

Mild cognitive impairment among rural-dwelling older adults in China: A community-based study.

BACKGROUND: Epidemiological studies of mild cognitive impairment (MCI) and subtypes of MCI have rarely focused on rural residents in China. METHODS: This population-based study included 5068 participants (age ≥60 years) who were living in rural communities. We defined MCI, amnestic MCI (aMCI), and non-amnestic MCI (naMCI) following the Petersen's criteria that integrated neuropsychological assessments with in-person clinical evaluations. RESULTS: The overall prevalence of MCI, aMCI, and naMCI was 26.48%, 22.30%, and 4.18%, respectively. The prevalence of MCI increased with age. The adjusted odds ratio (OR) of MCI was 0.71 (95% confidence interval [CI] 0.61 to 0.82) for primary school (vs. illiteracy), 0.30 (0.24 to 0.39) for middle school or above, 1.35 (1.09 to 1.67) for being farmers, 0.65 (0.54 to 0.78) for alcohol consumption, 1.43 (1.20 to 1.70) for stroke history, and 1.14 (0.95 to 1.36) for any apolipoprotein E (APOE) ε4 allele (vs ε3/ε3). CONCLUSIONS: MCI affects over one-fourth of rural older adults in China. Overall MCI was associated with demographic factors, non-alcohol consumption, and stroke, but not with APOE genotype and cardiometabolic factors.

Anosmia, mild cognitive impairment, and biomarkers of brain aging in older adults.

Olfactory impairment is a potential marker for prodromal dementia, but the underlying mechanisms are poorly understood. This population-based study included 4214 dementia-free participants (age ≥65 years). Olfaction was assessed using the 16-item Sniffin' Sticks identification test. In the subsamples, we measured plasma amyloid beta (Aß)40, Aß42, total tau, and neurofilament light chain (NfL; n = 1054); and quantified hippocampal, entorhinal cortex, and white matter hyperintensity (WMH) volumes, and Alzheimer's disease (AD)-signature cortical thickness (n = 917). Data were analyzed with logistic and linear regression models. In the total sample, mild cognitive impairment (MCI) was diagnosed in 1102 persons (26.2%; amnestic MCI, n = 931; non-amnestic MCI, n = 171). Olfactory impairment was significantly associated with increased likelihoods of MCI, amnestic MCI, and non-amnestic MCI. In the subsamples, anosmia was significantly associated with higher plasma total tau and NfL concentrations, smaller hippocampal and entorhinal cortex volumes, and greater WMH volume, and marginally with lower AD-signature cortical thickness. These results suggest that cerebral neurodegenerative and microvascular lesions are common neuropathologies linking anosmia with MCI in older adults.

Perceptual odor qualities predict successful odor identification in old age.

Odor identification is a common assessment of olfaction, and it is affected in a large number of diseases. Identification abilities decline with age, but little is known about whether there are perceptual odor features that can be used to predict identification. Here, we analyzed data from a large, population-based sample of 2,479 adults, aged 60 years or above, from the Swedish National study on Aging and Care in Kungsholmen. Participants performed both free and cued odor identification tests. In a separate experiment, we assessed perceived pleasantness, familiarity, intensity, and edibility of all odors in the first sample, and examined how odor identification performance is associated with these variables. The analysis showed that high-intensity odors are easier to identify than low-intensity odors overall, but also that they are more susceptible to the negative repercussions of old age. This result indicates that sensory decline is a major aspect of age-dependent odor identification impairment, and suggests a framework where identification likelihood is proportional to the perceived intensity of the odor. Additional analyses further showed that high-performing individuals can discriminate target odors from distractors along the pleasantness and edibility dimensions and that unpleasant and inedible odors show smaller age-related differences in identification. Altogether, these results may guide further development and optimization of brief and efficient odor identification tests as well as influence the design of odorous products targeted toward older consumers.

Trajectories of cognitive decline and dementia development: A 12-year longitudinal study.

INTRODUCTION: Mapping the preclinical dementia phase is important for early detection and evaluation of interventions. We assessed the trajectories of cognitive decline in preclinical dementia over 12 years and investigated whether being a fast decliner across 6 years is associated with increased risk of dementia the following 6 years. METHODS: Rates of cognitive decline were determined using mixed-effects models for 1646 participants from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K) cohort. Cox regression was used to assess the future likelihood of dementia for fast decliners (declining ≥1.5 standard deviations [SDs] faster than the age-specific rates). RESULTS: Participants in a preclinical phase of dementia showed increased rates of decline in all cognitive tests compared to the no-dementia group, particularly closer (0-6 years) to diagnosis. Participants declining fast in three or more cognitive tests 12-6 years before diagnosis demonstrated a high risk of dementia 6 years later (hazard ratio [HR] 3.90, 95% confidence interval [CI] 2.28-6.69). DISCUSSION: Being a fast decliner is linked to increased risk of future dementia.

Pulmonary function is associated with cognitive decline and structural brain differences.

The association of poor pulmonary function (PF) with cognitive trajectories and structural brain differences remains unclear. Within the Rush Memory and Aging Project, 1377 dementia-free subjects were followed up to 21 years. PF was assessed with a composite score measured at baseline. Global and domain-specific cognitive function was assessed annually constructed from 19 cognitive tests. A subsample of 351 participants underwent brain magnetic resonance imaging to investigate the cross-sectional association between PF and structural brain volumes. We found that low PF was related to faster decline in global cognition, and domain-specific function including episodic memory, semantic memory, working memory, visuospatial ability, and perceptual speed. In addition, low PF was associated with smaller volumes of total brain, white matter and gray matter, and larger white matter hyperintensities volume. Our results suggest that low PF is associated with faster cognitive decline, and both neurodegeneration and vascular brain lesions may underlie the association.

Cardiometabolic multimorbidity accelerates cognitive decline and dementia progression.

INTRODUCTION: Cardiometabolic diseases (CMDs) have been individually associated with adverse cognitive outcomes, but their combined effect has not been investigated. METHODS: A total of 2577 dementia-free participants 60 years of age or older were followed for 12 years to observe changes in cognitive function and to detect incident cognitive impairment, no dementia (CIND) and dementia. CMDs (including type 2 diabetes, heart disease, and stroke) were assessed at baseline through medical records and clinical examinations. Cardiometabolic multimorbidity was defined as the presence of two or more CMDs. Data were analyzed using multi-adjusted linear mixed-effects models, Cox regression, and Laplace regression. RESULTS: CMD multimorbidity was associated with cognitive decline, CIND (hazard ratio [HR] 1.73; 95% confidence interval CI 1.23 to 2.44), and its progression to dementia (HR 1.86; 95% CI 1.17 to 2.97). CMD multimorbidity accelerated the onset of CIND by 2.3 years and dementia by 1.8 years. CONCLUSIONS: CMD multimorbidity accelerates cognitive decline and increases the risk of both CIND and its conversion to dementia. HIGHLIGHTS: We explored the combined impact of cardiometabolic diseases (CMDs) on cognition. An increasing number of CMDs dose-dependently accelerated cognitive decline. CMD multimorbidity increased the risk of both cognitive impairment and dementia. Co-morbid CMDs could be ideal targets for interventions to protect cognitive health.

Cerebral Small Vessel Disease Associated With Atrial Fibrillation Among Older Adults: A Population-Based Study.

Background and Purpose: Cerebral small vessel disease, as a potential mechanism underlying the association between atrial fibrillation (AF) and dementia, remains poorly investigated. In this cohort study, we sought to examine the association between AF and cerebral small vessel disease markers among older adults. Methods: Data on 336 participants (age ≥60 years, mean 70.2 years; 60.2% women) free of dementia, disability, and cerebral infarcts were derived from the population-based Swedish National Study on Aging and Care in Kungsholmen. Structural brain magnetic resonance imaging examinations were performed at baseline (2001­2004) and follow-ups (2004­2007 and 2007­2010). Magnetic resonance imaging markers of cerebral small vessel disease included perivascular spaces, lacunes, and volumes of white matter hyperintensities, lateral ventricles, and total brain tissue. AF was assessed at baseline and follow-ups through clinical examinations, electrocardiogram, and medical records. Data were analyzed using linear mixed-effects models. Results: At baseline, 18 persons (5.4%) were identified to have prevalent AF and 17 (5.6%) developed incident AF over the 6-year follow-up. After multivariable adjustment, AF was significantly associated with a faster annual increase in white matter hyperintensities volume (ß coefficient=0.45 [95% CI, 0.04­0.86]) and lateral ventricular volume (0.58 [0.13­1.02]). There was no significant association of AF with annual changes in perivascular spaces number (ß coefficient=0.53 [95% CI, −0.27 to 1.34]) or lacune number (−0.01 [−0.07 to 0.05]). Conclusions: Independent of cerebral infarcts, AF is associated with accelerated progression of white matter lesions and ventricular enlargement among older adults.

Elevated neuroinflammation contributes to the deleterious impact of iron overload on brain function in aging.

Intracellular iron is essential for many neurobiological mechanisms. However, at high concentrations, iron may induce oxidative stress and inflammation. Brain iron overload has been shown in various neurodegenerative disorders and in normal aging. Elevated brain iron in old age may trigger brain dysfunction and concomitant cognitive decline. However, the exact mechanism underlying the deleterious impact of iron on brain function in aging is unknown. Here, we investigated the role of iron on brain function across the adult lifespan from 187 healthy participants (20-79 years old, 99 women) who underwent fMRI scanning while performing a working-memory n-back task. Iron content was quantified using R2* relaxometry, whereas neuroinflammation was estimated using myo-inositol measured by magnetic resonance spectroscopy. Striatal iron increased non-linearly with age, with linear increases at both ends of adulthood. Whereas higher frontostriatal activity was related to better memory performance independent of age, the link between brain activity and iron differed across age groups. Higher striatal iron was linked to greater frontostriatal activity in younger, but reduced activity in older adults. Further mediation analysis revealed that, after age 40, iron provided unique and shared contributions with neuroinflammation to brain activations, such that neuroinflammation partly mediated brain-iron associations. These findings promote a novel mechanistic understanding of how iron may exert deleterious effects on brain function and cognition with advancing age.

The impact of diabetes on cognitive impairment and its progression to dementia.

INTRODUCTION: Diabetes is a well-established risk factor for dementia, but its impact on the prodromal phase of dementia is unclear. METHODS: Cohorts of older adults who were cognitively healthy (n = 1840) or had cognitive impairment-no dementia (CIND; n = 682) were followed over 12 years to detect incident CIND and dementia, respectively. RESULTS: Poorly controlled diabetes (glycated hemoglobin [HbA1c] ≥7.5%; reference = normoglycemia) was associated with double the risk of CIND (Cox regression multi-adjusted hazard ratio [HR] 2.01, 95% confidence interval [CI] 1.13-3.58) and triple the risk CIND progressing to dementia (HR 2.87, 95% CI 1.20-6.85). Co-morbid diabetes and heart disease doubled the risk of incident CIND and dementia, although neither disease conferred a significant risk of either outcome alone. Elevated systemic inflammation contributed to the diabetes-associated increased dementia risk. CONCLUSIONS: Diabetes characterized by poor glycemic control or cardiovascular complications is related to a greater risk of the development and progression of cognitive impairment. Inflammation may play a role in these relationships.

Temporolimbic cortical volume is associated with semantic odor memory performance in aging.

Olfactory function, and specifically semantic olfactory memory (i.e., odor identification), has frequently been shown to predict cognitive functioning across multiple domains in old age. This observation suggests that olfactory function can serve as a marker for the integrity of temporolimbic cortical networks, but a clear delineation of this association is still missing. To address this issue, the present study employed voxel-based morphometry in a region of interest-based design to determine the extent to which gray matter volumes of core olfactory and memory areas are associated with olfactory memory performance in an aging population free from neurodegenerative disease. We further aimed to determine potential overlap in structural anatomical correlates, and differences in association strength, for semantic and episodic olfactory memory. Structural magnetic resonance imaging (MRI), episodic and semantic odor memory and episodic and semantic verbal memory data were collected in 422 participants from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), all aged â€‹≥ â€‹60 years. Controlling for age and education, semantic, but not episodic, olfactory memory was positively related to gray matter volume in a cluster extending from the anterior hippocampus and amygdala into the posterior piriform cortex. The observed associations remained even when verbal memory performance was controlled for, supporting a link between the olfactory memory domain and cortical volume over and above more generalized memory abilities. As such, our data provide evidence for distinct functional-structural associations for semantic odor memory, supporting the idea of temporolimbic integrity as a neurobiological substrate linking olfactory function to cognitive health in old age.