Spectrum of cognition short of dementia: Framingham Heart Study and Mayo Clinic Study of Aging.

OBJECTIVE: To understand the neuropsychological basis of dementia risk among persons in the spectrum including cognitive normality and mild cognitive impairment. METHODS: We quantitated risk of progression to dementia in elderly persons without dementia from 2 population-based studies, the Framingham Heart Study (FHS) and Mayo Clinic Study of Aging (MCSA), aged 70 to 89 years at enrollment. Baseline cognitive status was defined by performance in 4 domains derived from batteries of neuropsychological tests (that were similar but not identical for FHS and MCSA) at cut scores corresponding to SDs of ≤-0.5, -1, -1.5, and -2 from normative means. Participants were characterized as having no cognitive impairment (reference group), or single or multiple amnestic or nonamnestic profiles at each cut score. Incident dementia over the following 6 years was determined by consensus committee at each study separately. RESULTS: The pattern of hazard ratios for incident dementia, rates of incident dementia and positive predictive values across cognitive test cut scores, and number of affected domains was similar although not identical across the FHS and MCSA. Dementia risks were higher for amnestic profiles than for nonamnestic profiles, and for multidomain compared with single-domain profiles. CONCLUSIONS: Cognitive domain subtypes, defined by neuropsychologically derived cut scores and number of low-performing domains, differ substantially in prognosis in a conceptually logical manner that was consistent between FHS and MCSA. Neuropsychological characterization of elderly persons without dementia provides valuable information about prognosis. The heterogeneity of risk of dementia cannot be captured concisely with one test or a single definition or cutpoint.

TAR DNA-binding protein 43 and pathological subtype of Alzheimer's disease impact clinical features.

OBJECTIVE: The aim of this study was to determine whether the frequency of TAR DNA-binding protein 43 (TDP-43) deposition in Alzheimer's disease (AD) differs across pathologically defined AD subtypes (hippocampal sparing [HpSp]; typical and limbic) and further examine the relationship between TDP-43, pathological subtype, and clinical features in AD. METHODS: We identified all cases with pathologically confirmed AD (NIA-Reagan intermediate-high probability, Braak stage IV-VI) independent of cognitive status (n = 188). Neurofibrillary tangle counts were performed using thioflavin-S microscopy in hippocampus and three neocortical regions, and all cases were subtyped: HpSp AD pathology (n = 19); typical AD pathology (n = 136); and limbic AD pathology (n = 33). TDP-43 immunoreactivity was performed in multiple brain regions to assess for the presence of TDP-43 and TDP-43 stage. All cases were clinically subclassified at presentation as amnestic AD dementia versus atypical AD dementia. Statistical analysis was performed using linear and penalized logistic regression to assess associations with pathological subtype, and the effects of TDP-43, accounting for possible interactions between pathological subtype and TDP-43. RESULTS: TDP-43 deposition was frequent in typical (59%) and limbic AD pathologies (67%), but not HpSp AD pathology (21%; p = 0.003). The observed associations of TDP-43 with greater memory loss, naming and functional decline, and smaller hippocampal volumes, closest to death, did not differ across AD pathological subtype. Clinical presentation was associated with pathological subtype (p = 0.01), but not TDP-43 (p = 0.69). INTERPRETATION: Although the frequency of TDP-43 deposition in AD varies by pathological subtype, the observed effects of TDP-43 on clinical/magnetic resonance imaging features are consistent across pathological subtypes. Clinical presentation in AD is driven by pathological subtype, not by TDP-43.

Late-onset Alzheimer's risk variants in memory decline, incident mild cognitive impairment, and Alzheimer's disease.

We tested association of nine late-onset Alzheimer's disease (LOAD) risk variants from genome-wide association studies (GWAS) with memory and progression to mild cognitive impairment (MCI) or LOAD (MCI/LOAD) in older Caucasians, cognitively normal at baseline and longitudinally evaluated at Mayo Clinic Rochester and Jacksonville (n>2000). Each variant was tested both individually and collectively using a weighted risk score. APOE-e4 associated with worse baseline memory and increased decline with highly significant overall effect on memory. CLU-rs11136000-G associated with worse baseline memory and incident MCI/LOAD. MS4A6A-rs610932-C associated with increased incident MCI/LOAD and suggestively with lower baseline memory. ABCA7-rs3764650-C and EPHA1-rs11767557-A associated with increased rates of memory decline in subjects with a final diagnosis of MCI/LOAD. PICALM-rs3851179-G had an unexpected protective effect on incident MCI/LOAD. Only APOE-inclusive risk scores associated with worse memory and incident MCI/LOAD. The collective influence of the nine top LOAD GWAS variants on memory decline and progression to MCI/LOAD appears limited. Discovery of biologically functional variants at these loci may uncover stronger effects on memory and incident disease.

Incidence of dementia among participants and nonparticipants in a longitudinal study of cognitive aging.

Although rates of incident dementia have been reported from several populations, the impact of nonparticipation on dementia incidence in studies of cognitive aging is unknown. In 2004, investigators with the Mayo Clinic Study of Aging selected persons aged 70-89 years from an enumeration of all Olmsted County, Minnesota, residents (age- and sex-stratified random sample). Of 4,398 potential participants, 2,050 agreed to undergo an in-person health assessment. Those participants were reevaluated in person using standard diagnostic procedures approximately every 15 months over a median follow-up period of 5.7 years (through September 15, 2013). There were 1,679 persons who refused any participation. A trained nurse abstractor reviewed the medical records of nonparticipants using the Rochester Epidemiology Project's medical record linkage system a median of 3.9 years after refusal. Nonparticipants had a higher prevalence of dementia than participants evaluated in person (6.5% vs. 3.3%; P < 0.0001). The standardized incidence of dementia was not significantly higher among the nonparticipants (23.2 per 1,000 person-years) than in those evaluated in person (19.6 per 1,000 person-years; hazard ratio = 1.17, 95% confidence interval: 0.95, 1.43 (P = 0.13); adjusted for education and sex, with age as the time scale). The small, nonsignificant impact of nonparticipation on rates of incident dementia is reassuring for future studies based on incident dementia cases.

TDP-43 is a key player in the clinical features associated with Alzheimer's disease.

The aim of this study was to determine whether the TAR DNA-binding protein of 43 kDa (TDP-43) has any independent effect on the clinical and neuroimaging features typically ascribed to Alzheimer's disease (AD) pathology, and whether TDP-43 pathology could help shed light on the phenomenon of resilient cognition in AD. Three-hundred and forty-two subjects pathologically diagnosed with AD were screened for the presence, burden and distribution of TDP-43. All had been classified as cognitively impaired or normal, prior to death. Atlas-based parcellation and voxel-based morphometry were used to assess regional atrophy on MRI. Regression models controlling for age at death, apolipoprotein ε4 and other AD-related pathologies were utilized to explore associations between TDP-43 and cognition or brain atrophy, stratified by Braak stage. In addition, we determined whether the effects of TDP-43 were mediated by hippocampal sclerosis. One-hundred and ninety-five (57%) cases were TDP-positive. After accounting for age, apolipoprotein ε4 and other pathologies, TDP-43 had a strong effect on cognition, memory loss and medial temporal atrophy in AD. These effects were not mediated by hippocampal sclerosis. TDP-positive subjects were 10× more likely to be cognitively impaired at death compared to TDP-negative subjects. Greater cognitive impairment and medial temporal atrophy were associated with greater TDP-43 burden and more extensive TDP-43 distribution. TDP-43 is an important factor in the manifestation of the clinico-imaging features of AD. TDP-43 also appears to be able to overpower what has been termed resilient brain aging. TDP-43 therefore should be considered a potential therapeutic target for the treatment of AD.

Association of type 2 diabetes with brain atrophy and cognitive impairment.

OBJECTIVE: We investigated the associations of diabetes and hypertension with imaging biomarkers (markers of neuronal injury and ischemic damage) and with cognition in a population-based cohort without dementia. METHODS: Participants (n = 1,437, median age 80 years) were evaluated by a nurse and physician and underwent neuropsychological testing. A diagnosis of cognitively normal, mild cognitive impairment (MCI), or dementia was made by an expert panel. Participants underwent MRI to determine cortical and subcortical infarctions, white matter hyperintensity (WMH) volume, hippocampal volume (HV), and whole brain volume (WBV). The medical records were reviewed for diabetes and hypertension in midlife or later. RESULTS: Midlife diabetes was associated with subcortical infarctions (odds ratio, 1.85 [95% confidence interval, 1.09-3.15]; p = 0.02), reduced HV (-4% [-7 to -1.0]; p = 0.01), reduced WBV (-2.9% [-4.1 to -1.6]), and prevalent MCI (odds ratio, 2.08; p = 0.01). The association between diabetes and MCI persisted with adjustment for infarctions and WMH volume but was attenuated after adjustment for WBV (1.60 [0.87-2.95]; p = 0.13) and HV (1.82 [1.00-3.32]; p = 0.05). Midlife hypertension was associated with infarctions and WMH volume and was marginally associated with reduced performance in executive function. Effects of late-life onset of diabetes and hypertension were few. CONCLUSIONS: Midlife onset of diabetes may affect late-life cognition through loss of brain volume. Midlife hypertension may affect executive function through ischemic pathology. Late-life onset of these conditions had fewer effects on brain pathology and cognition.

Evaluation of memory endophenotypes for association with CLU, CR1, and PICALM variants in black and white subjects.

BACKGROUND: Genetic variants at the CLU, CR1, and PICALM loci associate with risk for late-onset Alzheimer's disease (LOAD) in genomewide association studies. In this study, our aim was to determine whether the LOAD risk variants at these three loci influence memory endophenotypes in black and white subjects. METHODS: We pursued an association study between single nucleotide polymorphism genotypes at the CLU, CR1, and PICALM loci and memory endophenotypes. We assessed black subjects (AA series: 44 with LOAD and 224 control subjects) recruited at Mayo Clinic Florida and whites recruited at Mayo Clinic Minnesota (RS series: 372 with LOAD and 1690 control subjects) and Florida (JS series: 60 with LOAD and 529 control subjects). Single nucleotide polymorphisms at the LOAD risk loci CLU (rs11136000), CR1 (rs6656401, rs3818361), and PICALM (rs3851179) were genotyped and tested for association with Logical Memory immediate recall, Logical Memory delayed recall, Logical Memory percent retention, Visual Reproduction immediate recall, Visual Reproduction delayed recall, and Visual Reproduction percent retention scores from the Wechsler Memory Scale-Revised using multivariable linear regression analysis, adjusting for age at exam, sex, education, and apolipoprotein E ε4 dosage. RESULTS: We identified nominally significant or suggestive associations between the LOAD-risky CR1 variants and worse Logical Memory immediate recall scores in blacks (P = .068-.046, ß = -2.7 to -1.2). The LOAD-protective CLU variant is associated with better logical memory endophenotypes in white subjects (P = .099-.027, ß = 0.31-0.93). The CR1 associations persisted when the control subjects from the AA series were assessed separately. The CLU associations appeared to be driven by one of the white series (RS) and were also observed when the control subset from RS was analyzed. CONCLUSION: These results suggest for the first time that LOAD risk variants at CR1 may influence memory endophenotypes in blacks. In addition, the CLU LOAD-protective variant may confer enhanced memory in whites. Although these results would not remain significant after stringent corrections for multiple testing, they need to be considered in the context of the LOAD associations with which they have biological consistency. They also provide estimates for effect sizes on memory endophenotypes that could guide future studies. The detection of memory effects for these variants in clinically normal subjects, implies that these LOAD risk loci might modify memory prior to clinical diagnosis of AD.

Association of diabetes with amnestic and nonamnestic mild cognitive impairment.

BACKGROUND: Type 2 diabetes may increase the risk of amnestic mild cognitive impairment (aMCI) through Alzheimer's disease (AD)-related and vascular pathology and may also increase the risk of nonamnestic MCI (naMCI) through vascular disease mechanisms. We examined the association of type 2 diabetes with mild cognitive impairment (MCI) and MCI subtype (aMCI and naMCI) overall and by sex. METHODS: Participants were Olmsted County, Minnesota residents (70 years and older) enrolled in a prospective, population-based study. At baseline and every 15 months thereafter, participants were evaluated using the Clinical Dementia Rating scale, a neurological evaluation, and neuropsychological testing for a diagnosis of normal cognition, MCI, and dementia by a consensus panel. Type 2 diabetes was ascertained from the medical records of participants at baseline. RESULTS: Over a median 4.0 years of follow-up, 348 of 1450 subjects developed MCI. Type 2 diabetes was associated (hazard ratio [95% confidence interval]) with MCI (1.39 [1.08-1.79]), aMCI (1.58 [1.17-2.15]; multiple domain: 1.58 [1.01-2.47]; single domain: 1.49 [1.09-2.05]), and the hazard ratio for naMCI was elevated (1.37 [0.84-2.24]). Diabetes was strongly associated with multiple-domain aMCI in men (2.42 [1.31-4.48]) and an elevated risk of multiple domain naMCI in men (2.11 [0.70-6.33]), and with single domain naMCI in women (2.32 [1.04-5.20]). CONCLUSIONS: Diabetes was associated with an increased risk of MCI in elderly persons. The association of diabetes with MCI may vary with subtype, number of domains, and sex. Prevention and control of diabetes may reduce the risk of MCI and Alzheimer's disease.

Higher risk of progression to dementia in mild cognitive impairment cases who revert to normal.

OBJECTIVE: To estimate rates of progression from mild cognitive impairment (MCI) to dementia and of reversion from MCI to being cognitively normal (CN) in a population-based cohort. METHODS: Participants (n = 534, aged 70 years and older) enrolled in the prospective Mayo Clinic Study of Aging were evaluated at baseline and every 15 months to identify incident MCI or dementia. RESULTS: Over a median follow-up of 5.1 years, 153 of 534 participants (28.7%) with prevalent or incident MCI progressed to dementia (71.3 per 1,000 person-years). The cumulative incidence of dementia was 5.4% at 1 year, 16.1% at 2, 23.4% at 3, 31.1% at 4, and 42.5% at 5 years. The risk of dementia was elevated in MCI cases (hazard ratio [HR] 23.2, p < 0.001) compared with CN subjects. Thirty-eight percent (n = 201) of MCI participants reverted to CN (175.0/1,000 person-years), but 65% subsequently developed MCI or dementia; the HR was 6.6 (p < 0.001) compared with CN subjects. The risk of reversion was reduced in subjects with an APOE ε4 allele (HR 0.53, p < 0.001), higher Clinical Dementia Rating Scale-Sum of Boxes (HR 0.56, p < 0.001), and poorer cognitive function (HR 0.56, p < 0.001). The risk was also reduced in subjects with amnestic MCI (HR 0.70, p = 0.02) and multidomain MCI (HR 0.61, p = 0.003). CONCLUSIONS: MCI cases, including those who revert to CN, have a high risk of progressing to dementia. This suggests that diagnosis of MCI at any time has prognostic value.

Practice effects and longitudinal cognitive change in normal aging vs. incident mild cognitive impairment and dementia in the Mayo Clinic Study of Aging.

The objective of this study was to examine practice effects and longitudinal cognitive change in a population-based cohort classified as clinically normal at their initial evaluation. We examined 1390 individuals with a median age of 78.1 years and re-evaluated them up to four times at approximate 15-month intervals, with an average follow-up time of 5 years. Of the 1390 participants, 947 (69%) individuals remained cognitively normal, 397 (29%) progressed to mild cognitive impairment (MCI), and 46 (3%) to dementia. The stable normal group showed an initial practice effect in all domains which was sustained in memory and visuospatial reasoning. There was only a slight decline in attention and language after visit 3. We combined individuals with incident MCI and dementia to form one group representing those who declined. The incident MCI/dementia group showed an unexpected practice effect in memory from baseline to visit 2, with a significant decline thereafter. This group did not demonstrate practice effects in any other domain and showed a downward trajectory in all domains at each evaluation. Modeling cognitive change in an epidemiologic sample may serve as a useful benchmark for evaluating cognitive change in future intervention studies.

MRI and MRS predictors of mild cognitive impairment in a population-based sample.

OBJECTIVE: To investigate MRI and proton magnetic resonance spectroscopy (MRS) predictors of mild cognitive impairment (MCI) in cognitively normal older adults. METHODS: Subjects were cognitively normal older adults (n = 1,156) who participated in the population-based Mayo Clinic Study of Aging MRI/MRS study from August 2005 to December 2010 and had at least one annual clinical follow-up. Single-voxel MRS was performed from the posterior cingulate gyri, and hippocampal volumes and white matter hyperintensity volumes were quantified using automated methods. Brain infarcts were assessed on MRI. Cox proportional hazards regression, with age as the time scale, was used to assess the effect of MRI and MRS markers on the risk of progression from cognitively normal to MCI. Linear mixed-effects models were used to assess the effect of MRI and MRS markers on cognitive decline. RESULTS: After a median follow-up of 2.8 years, 214 participants had progressed to MCI or dementia (estimated incidence rate = 6.1% per year; 95% confidence interval = 5.3%-7.0%). In univariable modeling, hippocampal volume, white matter hyperintensity volume, and N-acetylaspartate/myo-inositol were significant predictors of MCI in cognitively normal older adults. In multivariable modeling, only decreased hippocampal volume and N-acetylaspartate/myo-inositol were independent predictors of MCI. These MRI/MRS predictors of MCI as well as infarcts were associated with cognitive decline (p < 0.05). CONCLUSION: Quantitative MRI and MRS markers predict progression to MCI and cognitive decline in cognitively normal older adults. MRS may contribute to the assessment of preclinical dementia pathologies by capturing neurodegenerative changes that are not detected by hippocampal volumetry.

Mild cognitive impairment due to Alzheimer disease in the community.

OBJECTIVE: The newly proposed National Institute on Aging-Alzheimer's Association (NIA-AA) criteria for mild cognitive impairment (MCI) due to Alzheimer disease (AD) suggest a combination of clinical features and biomarker measures, but their performance in the community is not known. METHODS: The Mayo Clinic Study of Aging (MCSA) is a population-based longitudinal study of nondemented subjects in Olmsted County, Minnesota. A sample of 154 MCI subjects from the MCSA was compared to a sample of 58 amnestic MCI subjects from the Alzheimer's Disease Neuroimaging Initiative 1 (ADNI-1) to assess the applicability of the criteria in both settings and to assess their outcomes. RESULTS: Fourteen percent of MCSA and 16% of ADNI-1 of subjects were biomarker negative. In addition, 14% of MCSA and 12% of ADNI-1 subjects had evidence for amyloid deposition only, whereas 43% of MCSA and 55% of ADNI-1 subjects had evidence for amyloid deposition plus neurodegeneration (magnetic resonance imaging atrophy, fluorodeoxyglucose positron emission tomography hypometabolism, or both). However, a considerable number of subjects had biomarkers inconsistent with the proposed AD model; for example, 29% of MCSA subjects and 17% of ADNI-1 subjects had evidence for neurodegeneration without amyloid deposition. These subjects may not be on an AD pathway. Neurodegeneration appears to be a key factor in predicting progression relative to amyloid deposition alone. INTERPRETATION: The NIA-AA criteria apply to most MCI subjects in both the community and clinical trials settings; however, a sizeable proportion of subjects had conflicting biomarkers, which may be very important and need to be explored.

Cardiac disease associated with increased risk of nonamnestic cognitive impairment: stronger effect on women.

OBJECTIVE: To investigate the association of cardiac disease with amnestic and nonamnestic mild cognitive impairment (aMCI and naMCI, respectively). Nonamnestic mild cognitive impairment, a putative precursor of vascular and other non-Alzheimer dementias, is hypothesized to have a vascular etiology. DESIGN: A prospective, population-based, cohort study with a median 4.0 years of follow-up. SETTING: Olmsted County, Minnesota. PARTICIPANTS: A total of 2719 participants were evaluated at baseline and every 15 months using the Clinical Dementia Rating scale, a neurological evaluation, and neuropsychological testing. A diagnosis of normal cognition, MCI, or dementia was made by consensus. Cardiac disease at baseline was assessed from the participant's medical records. MAIN OUTCOME MEASURES: Incident MCI, aMCI, or naMCI. RESULTS: Of 1450 participants without MCI or dementia at baseline, 366 developed MCI. Cardiac disease was associated with an increased risk of naMCI (hazard ratio, 1.77 [95% CI, 1.16-2.72]). However, the association varied by sex (P = .02 for interaction). Cardiac disease was associated with an increased risk of naMCI (hazard ratio, 3.07 [95% CI, 1.58-5.99]) for women but not for men (hazard ratio, 1.16 [95% CI, 0.68-1.99]). Cardiac disease was not associated with any type of MCI or with aMCI. CONCLUSIONS: Cardiac disease is an independent risk factor for naMCI; within-sex comparisons showed a stronger association for women. Prevention and management of cardiac disease and vascular risk factors may reduce the risk of naMCI.

Clinical and electrophysiologic variability in amyotrophic lateral sclerosis within a kindred harboring the C9ORF72 repeat expansion.

Our objective was to characterize the motor neuron disease features within a large c9FTD/ALS kindred. We analyzed clinical, electrophysiologic and neuropathologic data in a c9FTD/ALS kindred of Scandinavian ancestry. Results showed that of six family members affected, three had only ALS, two had FTD and one had FTD and ALS. Each patient with motor neuron disease had a different clinical presentation: one patient had only bulbar symptoms, one had bulbar and limb involvement, one had limb symptoms, and one had primarily upper motor neuron disease. Later in the course of disease, all ALS patients developed bulbar involvement and died from respiratory causes. Survival was uniformly short (two to five years). Electrophysiologic studies recorded progressive lower motor neuron dysfunction except in the patient with predominantly upper motor neuron features. In conclusion, this kindred demonstrates that the presentation of ALS within c9FTD/ALS families may vary considerably and electrophysiologic findings reflect this heterogeneity.

Assessing the temporal relationship between cognition and gait: slow gait predicts cognitive decline in the Mayo Clinic Study of Aging.

BACKGROUND: The association between gait speed and cognition has been reported; however, there is limited knowledge about the temporal associations between gait slowing and cognitive decline among cognitively normal individuals. METHODS: The Mayo Clinic Study of Aging is a population-based study of Olmsted County, Minnesota, United States, residents aged 70-89 years. This analysis included 1,478 cognitively normal participants who were evaluated every 15 months with a nurse visit, neurologic evaluation, and neuropsychological testing. The neuropsychological battery used nine tests to compute domain-specific (memory, language, executive function, and visuospatial skills) and global cognitive z-scores. Timed gait speed (m/s) was assessed over 25 feet (7.6 meters) at a usual pace. Using mixed models, we examined baseline gait speed (continuous and in quartiles) as a predictor of cognitive decline and baseline cognition as a predictor of gait speed changes controlling for demographics and medical conditions. RESULTS: Cross-sectionally, faster gait speed was associated with better performance in memory, executive function, and global cognition. Both cognitive scores and gait speed declined over time. A faster gait speed at baseline was associated with less cognitive decline across all domain-specific and global scores. These results were slightly attenuated after excluding persons with incident mild cognitive impairment or dementia. By contrast, baseline cognition was not associated with changes in gait speed. CONCLUSIONS: Our study suggests that slow gait precedes cognitive decline. Gait speed may be useful as a reliable, easily attainable, and noninvasive risk factor for cognitive decline.

An operational approach to National Institute on Aging-Alzheimer's Association criteria for preclinical Alzheimer disease.

OBJECTIVE: A workgroup commissioned by the Alzheimer's Association (AA) and the National Institute on Aging (NIA) recently published research criteria for preclinical Alzheimer disease (AD). We performed a preliminary assessment of these guidelines. METHODS: We employed Pittsburgh compound B positron emission tomography (PET) imaging as our biomarker of cerebral amyloidosis, and (18) fluorodeoxyglucose PET imaging and hippocampal volume as biomarkers of neurodegeneration. A group of 42 clinically diagnosed AD subjects was used to create imaging biomarker cutpoints. A group of 450 cognitively normal (CN) subjects from a population-based sample was used to develop cognitive cutpoints and to assess population frequencies of the different preclinical AD stages using different cutpoint criteria. RESULTS: The new criteria subdivide the preclinical phase of AD into stages 1 to 3. To classify our CN subjects, 2 additional categories were needed. Stage 0 denotes subjects with normal AD biomarkers and no evidence of subtle cognitive impairment. Suspected non-AD pathophysiology (SNAP) denotes subjects with normal amyloid PET imaging, but abnormal neurodegeneration biomarker studies. At fixed cutpoints corresponding to 90% sensitivity for diagnosing AD and the 10th percentile of CN cognitive scores, 43% of our sample was classified as stage 0, 16% stage 1, 12 % stage 2, 3% stage 3, and 23% SNAP. INTERPRETATION: This cross-sectional evaluation of the NIA-AA criteria for preclinical AD indicates that the 1-3 staging criteria coupled with stage 0 and SNAP categories classify 97% of CN subjects from a population-based sample, leaving only 3% unclassified. Future longitudinal validation of the criteria will be important.

Reliable change on the Boston naming test.

Serial assessments are commonplace in neuropsychological practice and used to document cognitive trajectory for many clinical conditions. However, true change scores may be distorted by measurement error, repeated exposure to the assessment instrument, or person variables. The present study provides reliable change indices (RCI) for the Boston Naming Test, derived from a sample of 844 cognitively normal adults aged 56 years and older. All participants were retested between 9 and 24 months after their baseline exam. Results showed that a 4-point decline during a 9-15 month retest period or a 6-point decline during a 16-24 month retest period represents reliable change. These cutoff values were further characterized as a function of a person's age and family history of dementia. These findings may help clinicians and researchers to characterize with greater precision the temporal changes in confrontation naming ability.

Probable rapid eye movement sleep behavior disorder increases risk for mild cognitive impairment and Parkinson disease: a population-based study.

OBJECTIVE: Rapid eye movement sleep behavior disorder (RBD) is associated with neurodegenerative disease and particularly with the synucleinopathies. Convenience samples involving subjects with idiopathic RBD have suggested an increased risk of incident mild cognitive impairment (MCI), dementia (usually dementia with Lewy bodies), and Parkinson disease (PD). There are no data on such risks in a population-based sample. METHODS: Cognitively normal subjects aged 70 to 89 years in a population-based study of aging who screened positive for probable RBD using the Mayo Sleep Questionnaire were followed at 15-month intervals. In a Cox proportional hazards model, we measured the risk of developing MCI, dementia, and PD among the exposed (probable RBD [pRBD](+)) and unexposed (pRBD(-)) cohorts. RESULTS: Forty-four subjects with pRBD(+) status at enrollment (median duration of pRBD features was 7.5 years) and 607 pRBD(-) subjects were followed prospectively for a median of 3.8 years. Fourteen of the pRBD(+) subjects developed MCI, and 1 developed PD (15/44 = 34% developed MCI/PD); none developed dementia. After adjustment for age, sex, education, and medical comorbidity, pRBD(+) subjects were at increased risk of MCI/PD (hazard ratio [HR], 2.2; 95% confidence interval [CI], 1.3-3.9; p = 0.005). Inclusion of subjects who withdrew from the study produced similar results, as did exclusion of subjects with medication-associated RBD. Duration of pRBD symptoms did not predict the development of MCI/PD (HR, 1.05 per 10 years; 95% CI, 0.84-1.3; p = 0.68). INTERPRETATION: In this population-based cohort study, we observed that pRBD confers a 2.2-fold increased risk of developing MCI/PD over 4 years.

Diagnostic validity of age and education corrections for the Mini-Mental State Examination in older African Americans.

OBJECTIVES: To investigate whether demographic (age and education) adjustments for the Mini-Mental State Examination (MMSE) attenuate mean score discrepancies between African-American and Caucasian adults and whether demographically adjusted MMSE scores improve the diagnostic classification accuracy of dementia in African-American adults over unadjusted MMSE scores. DESIGN: Cross-sectional study. SETTING: Community-dwelling adults participating in the Mayo Clinic Alzheimer's Disease Patient Registry and Alzheimer's Disease Research Center. PARTICIPANTS: Three thousand two hundred fifty-four adults (2,819 Caucasian, 435 African American) aged 60 and older. MEASUREMENTS: MMSE score at study entry. RESULTS: African-American adults had significantly lower unadjusted MMSE scores (23.0 ± 7.4) than Caucasian adults (25.3 ± 5.4). This discrepancy persisted despite adjustment of MMSE scores for age and years of education using established regression weights or newly derived weights. Controlling for dementia severity at baseline and adjusting MMSE scores for age and quality of education attenuated this discrepancy. In African-American adults, an age- and education-adjusted MMSE cut score of 23/24 provided optimal dementia classification accuracy, but this represented only a modest improvement over an unadjusted MMSE cut score of 22/23. The posterior probability of dementia in African-American adults is presented for various unadjusted MMSE cut scores and prevalence rates of dementia. CONCLUSION: Age, dementia severity at study entry, and quality of educational experience are important explanatory factors in understanding the existing discrepancies in MMSE performance between Caucasian and African-American adults. These findings support the use of unadjusted MMSE scores when screening older African Americans for dementia, with an unadjusted MMSE cut score of 22/23 yielding optimal classification accuracy.

Engaging in cognitive activities, aging, and mild cognitive impairment: a population-based study.

The authors investigated whether engaging in cognitive activities is associated with aging and mild cognitive impairment (MCI) in a cross-sectional study derived from an ongoing population-based study of normal cognitive aging and MCI in Olmsted County, MN. A random sample of 1,321 study participants ages 70 to 89 (N=1,124 cognitively normal persons, and N=197 subjects with MCI) were interviewed about the frequency of cognitive activities carried out in late life (within 1 year of the date of interview). Computer activities; craft activities, such as knitting, quilting, etc.; playing games; and reading books were associated with decreased odds of having MCI. Social activities, such as traveling, were marginally significant. Even though the point-estimates for reading magazines, playing music, artistic activities, and group activities were associated with reduced odds of having MCI, none of these reached statistical significance. The equally high prevalence of reading newspapers in both groups yielded no significant between-group difference.