Tiffany F. Hughes

Outcomes of mild cognitive impairment by definition: a population study.

BACKGROUND Mild cognitive impairment (MCI) has been defined in several ways. OBJECTIVE To determine the 1-year outcomes of MCI by different definitions at the population level. DESIGN Inception cohort with 1-year follow-up. Participants were classified as having MCI using the following definitions operationalized for this study: amnestic MCI by Mayo criteria, expanded MCI by International Working Group criteria, Clinical Dementia Rating (CDR) = 0.5, and a purely cognitive classification into amnestic and nonamnestic MCI. SETTING General community. PARTICIPANTS Stratified random population-based sample of 1982 individuals 65 years and older. MAIN OUTCOME MEASURES For each MCI definition, there were 3 possible outcomes: worsening (progression to dementia [CDR ≥ 1] or severe cognitive impairment), improvement (reversion to CDR = 0 or normal cognition), and stability (unchanged CDR or cognitive status). RESULTS Regardless of MCI definition, over 1 year, a small proportion of participants progressed to CDR > 1 (range, 0%-3%) or severe cognitive impairment (0%-20%) at rates higher than their cognitively normal peers. Somewhat larger proportions of participants improved or reverted to normal (6%-53%). Most participants remained stable (29%-92%). Where definitions focused on memory impairment and on multiple cognitive domains, higher proportions progressed and lower proportions reverted on the CDR. CONCLUSIONS As ascertained by several operational definitions, MCI is a heterogeneous entity at the population level but progresses to dementia at rates higher than in normal elderly individuals. Proportions of participants progressing to dementia are lower and proportions reverting to normal are higher than in clinical populations. Memory impairments and impairments in multiple domains lead to greater progression and lesser improvement. Research criteria may benefit from validation at the community level before incorporation into clinical practice.

Association between late-life body mass index and dementia The Kame Project

Objective: To examine the association between body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) and risk of dementia and its subtypes in late life. Methods: Participants were members of the Kame Project, a population-based prospective cohort study of 1,836 Japanese Americans living in King County, WA, who had a mean age of 71.8 years and were dementia-free at baseline (1992–1994), and were followed for incident dementia through 2001. Cox proportional hazards models were used to estimate the risk of dementia, Alzheimer disease (AD), and vascular dementia (VaD) controlling for demographic and lifestyle characteristics and vascular comorbidities as a function of baseline BMI, WC, and WHR and change in BMI over time. Results: Higher baseline BMI was significantly associated with a reduced risk of AD (hazard ratio [HR] = 0.56, 95% confidence interval [CI] = 0.33–0.97) in the fully adjusted model. Slower rate of decline in BMI was associated with a reduced risk of dementia (HR = 0.37, 95% CI = 0.14–0.98), with the association stronger for those who were overweight or obese (HR = 0.18, 95% CI = 0.05–0.58) compared to normal or underweight (HR = 1.00, 95% CI = 0.18–5.66) at baseline. Conclusion: Higher baseline body mass index (BMI) and slower declining BMI in late life are associated with a reduced risk of dementia, suggesting that low BMI or a faster decline in BMI in late life may be preclinical indicators of an underlying dementing illness, especially for those who were initially overweight or obese.

Modifiable Midlife Risk Factors for Late-Life Cognitive Impairment and Dementia

The baby boom generation is approaching the age of greatest risk for cognitive impairment and dementia. There is growing interest in strategies to modify the environment in midlife to increase the probability of maintaining cognitive health in late life. Several potentially modifiable risk factors have been studied in relation to cognitive impairment and dementia in late life, but methodological limitations of observational research have resulted in some inconsistencies across studies. The most promising strategies are maintaining cardiovascular health, engagement in mental, physical, and social activities, using alcohol in moderation, abstaining from tobacco use, and following a heart-healthy diet. Other factors that may influence cognitive health are occupational attainment, depression, personality, exposure to general anesthesia, head injury, postmenopausal hormone therapy, non-steroidal anti-inflammatory medications, and nutritional supplements such as antioxidants. Some long-term observational studies initiated in midlife or earlier, and some randomized controlled trials, have examined the effects of specific cognitive health promotion behaviors in midlife on the risk of cognitive impairment in late life. Overall, these studies provide limited support for risk reduction at this time. Recommendations and challenges for developing effective strategies to reduce the burden of cognitive impairment and dementia in the future are discussed.

Catechol‐O‐methyltransferase genotype modulates cancer treatment‐related cognitive deficits in breast cancer survivors

Recent attention has focused on the negative effects of chemotherapy on the cognitive performance of cancer survivors. The current study examined modification of this risk by catechol‐O‐methyltransferase (COMT) genotype based on evidence in adult populations that the presence of a Val allele is associated with poorer cognitive performance.

Midlife Fruit and Vegetable Consumption and Risk of Dementia in Later Life in Swedish Twins

OBJECTIVE Diet may be associated with risk of dementia and Alzheimer disease (AD). The authors examined the association between fruit and vegetable consumption in midlife and risk for all types of dementia and AD. METHODS Participants were 3,779 members of the Swedish Twin Registry who completed a diet questionnaire approximately 30 years before cognitive screening and full clinical evaluation for dementia as part of the study of dementia in Swedish Twins (HARMONY) study. Among the participants, 355 twins were diagnosed with dementia. Among these, 81 twin pairs were discordant for dementia (50 discordant for AD). Data were analyzed with logistic regression for the entire sample using generalized estimating equations to adjust for relatedness of twins and with conditional logistic regression for the co-twin control design. RESULTS In fully adjusted models, a medium or great proportion of fruits and vegetables in the diet, compared with no or small, was associated with a decreased risk of dementia and AD. This effect was observed among women and those with angina. Similar, but nonsignificant, odds ratios were found in the co-twin control analyses. CONCLUSION The findings suggest that higher fruit and vegetable consumption may reduce the risk of dementia, especially among women and those with angina pectoris in midlife.

Mild cognitive impairment: Incidence and vascular risk factors in a population-based cohort

Objective: We examined the incidence of mild cognitive impairment (MCI) and its potential vascular risk factors in a prospective population-based study. Methods: An age-stratified random population-based cohort (baseline n = 1,982), followed for up to 4 years, was annually assessed for cognitive and everyday functioning. Incidence rates were calculated for both cognitive (neuropsychological [NP]-MCI) and functional (Clinical Dementia Rating [CDR] = 0.5) definitions of MCI. Several measures of vascular, metabolic, and inflammatory risk were assessed at baseline. Risk factor analyses used interval censoring survival models, followed by joint modeling of both MCI and attrition due to mortality and illness. Results: Incidence rates for NP-MCI and CDR = 0.5 were 95 and 55 per 1,000 person-years. In individual joint models, risk factors for NP-MCI were diabetes and adiposity (waist: hip ratio), while APOE ε4 genotype and heart failure increased risk of attrition. Adiposity, stroke, heart failure, and diabetes were risk factors for nonamnestic MCI. For CDR = 0.5, risk factors were stroke and heart failure; heart failure and adiposity increased risk of attrition. In multivariable joint models combining all risk factors, adiposity increased risk of NP-MCI, while stroke and heart failure increased risk for CDR = 0.5. Current alcohol use appeared protective against all subtypes. Conclusion: Incidence of MCI increased with age regardless of definition and did not vary by sex or education. Several vascular risk factors elevated the risk of incident MCI, whether defined cognitively or functionally, but most were associated with nonamnestic MCI and CDR = 0.5. Controlling vascular risk may potentially reduce risk of MCI.

Engagement in Social Activities and Progression from Mild to Severe Cognitive Impairment: The MYHAT Study

BACKGROUND It is of considerable public health importance to prevent or delay the progression of mild cognitive impairment (MCI) to more severely impaired cognitive states. This study examines the risk of progression from mild to severe cognitive impairment in relation to engagement in social activities while mildly impaired and the concurrence of subsequent change in engagement with MCI progression. METHODS Participants were 816 older adults with cognitively defined MCI (mean age 78.0 (standard deviation or SD = 7.4) years) from the Monongahela-Youghiogheny Healthy Aging Team (MYHAT) Study--a prospective cohort study of MCI in the community. Over three years of follow-up, 78 individuals progressed from MCI to severe cognitive impairment, while 738 did not progress. Risk of progression was estimated using discrete time survival analyses. The main predictors were standardized composite measures of the variety and frequency of engagement in social activities. RESULTS Lower risk of progression from mild to severe cognitive impairment was associated with both a greater level of frequency of engagement in social activities while mildly impaired (OR = 0.72, 95% CI: 0.55-0.93, p = 0.01) and also with a slower rate of decline in the variety of activities over time (OR = 0.01, 95% CI: <0.001-0.38, p = 0.02). CONCLUSIONS Greater engagement in social activities may potentially be beneficial for preventing or delaying further cognitive decline among older adults with MCI. Alternatively, lesser engagement in social activities may be a marker of impending cognitive decline in MCI.

Subjective cognitive complaints of older adults at the population level: An item response theory analysis

Subjective cognitive complaints (SCCs) are increasingly a focus in studies on prodromal Alzheimer disease (AD) and risk for dementia. Little is known about the optimal approach to measure SCCs. We used item response theory (IRT) to examine the characteristics of 24 SCC items in a sample of 3495 older adults pooled from 4 community-based studies. We investigated the potential advantages of IRT scoring over conventional scoring on the basis of participants’ item response patterns. Items most likely endorsed by individuals low in SCC severity relate to word retrieval and general subjective memory decline. Items likely endorsed only by individuals high in SCC severity relate to nonepisodic memory changes, such as decline in comprehension, judgment and executive functions, praxis and procedural memory, and social behavior changes. Above and beyond conventional total score, IRT scoring of SCCs was associated with performance on objective cognitive tests, and was associated with cognitive test performance among participants endorsing only 1 SCC item. Thus, IRT scoring captures additional information beyond a simple sum of SCC symptoms. Modern psychometric approaches including IRT may be useful in developing: (1) brief community screening questionnaires; and (2) more sensitive measures of very subtle subjective decline for use in prodromal Alzheimer disease research.

The Prevalence of Mild Cognitive Impairment in Diverse Geographical and Ethnocultural Regions: The COSMIC Collaboration

Background Changes in criteria and differences in populations studied and methodology have produced a wide range of prevalence estimates for mild cognitive impairment (MCI). Methods Uniform criteria were applied to harmonized data from 11 studies from USA, Europe, Asia and Australia, and MCI prevalence estimates determined using three separate definitions of cognitive impairment. Results The published range of MCI prevalence estimates was 5.0%–36.7%. This was reduced with all cognitive impairment definitions: performance in the bottom 6.681% (3.2%–10.8%); Clinical Dementia Rating of 0.5 (1.8%–14.9%); Mini-Mental State Examination score of 24–27 (2.1%–20.7%). Prevalences using the first definition were 5.9% overall, and increased with age (P < .001) but were unaffected by sex or the main races/ethnicities investigated (Whites and Chinese). Not completing high school increased the likelihood of MCI (P ≤ .01). Conclusion Applying uniform criteria to harmonized data greatly reduced the variation in MCI prevalence internationally.

Mild Cognitive Deficits and Everyday Functioning Among Older Adults in the Community: The Monongahela-Youghiogheny Healthy Aging Team Study

OBJECTIVE : A key component of successful aging is the ability to independently perform instrumental activities of daily living (IADL). We examined the ability to perform multiple IADL tasks in relation to mild cognitive impairment (MCI) defined on purely neuropsychological grounds. DESIGN : Cross-sectional study. SETTING : Population-based cohort in southwestern Pennsylvania. PARTICIPANTS : One thousand seven hundred thirty-seven community-dwelling adults age 65 years and older. MEASUREMENTS : Classification of MCI based on performance with reference to norms in the cognitive domains of memory, language, attention, executive, and visuospatial functions. The ability to perform seven IADL tasks (traveling, shopping, preparing meals, doing housework, taking medications, handling personal finances, and using the telephone) as assessed by the Older Americans Resources and Services scale. RESULTS : Those with cognitively defined MCI were more likely to be dependent in at least one IADL task, as well as in each individual IADL task, than cognitively normal participants. Better memory and executive functioning were associated with lower odds of IADL dependence in MCI. Across the subtypes of MCI, those with the multiple-domain amnestic subtype were most likely to be dependent in all IADL tasks, with better executive functioning associated with lower risk of dependence in select IADL tasks in this group. CONCLUSIONS : Mild impairment in cognition is associated with difficulty performing IADL tasks at the population level. Understanding these associations may help improve prediction of the outcomes of MCI. It may also allow appropriate targeting of cognitive interventions in MCI to potentially help preserve functional independence.