Association of Circulating Caprylic Acid with Risk of Mild Cognitive Impairment and Alzheimer's Disease in the Alzheimer's Disease Neuroimaging Initiative (ADNI) Cohort.

OBJECTIVE: Medium-chain fatty acids (MCFAs) can rapidly cross the blood-brain barrier and provide an alternative energy source for the brain. This study aims to determine 1) whether plasma caprylic acid (C8:0) is associated with risk of incident mild cognitive impairment (MCI) among baseline cognitively normal (CN) participants, and incident Alzheimer's Disease (AD) among baseline MCI participants; and 2) whether these associations differ by sex, comorbidity of cardiometabolic diseases, apolipoprotein E (APOE) ε4 alleles, and ADAS-Cog 13. METHODS: Within the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort, plasma C8:0 was measured at baseline in 618 AD-free participants aged 55 to 91. Logistic regression models were used to estimate odds ratios (ORs) and 95% CIs with incident MCI and AD as dependent variables, separately. RESULTS: The inverse association between circulating C8:0 and risk of incident MCI was of borderline significance. The inverse association between circulating levels of C8:0 and risk of incident MCI was significant among CN participants with ≥1 cardiometabolic diseases [OR (95% CI): 0.75 (0.58-0.98) (P=0.03)], those with one copy of APOE ε4 alleles [OR (95% CI): 0.43 (0.21-0.89) (P=0.02)], female [OR (95% CI): 0.60 (0.38-0.94) (P=0.02)], and ADAS-Cog 13 above the median [OR (95%CI): 0.69 (0.50-0.97)(P=0.03)] after adjusting for all covariates. CONCLUSION: The inverse associations were present only among subgroups of CN participants, including female individuals, those with one or more cardiometabolic diseases, or one APOE ε4 allele, or higher ADAS-Cog 13 scores. If confirmed, this finding will facilitate precision prevention of MCI, in turn, AD among CN older adults.

The practice of neurology, 2000-2010: report of the AAN Member Research Subcommittee.

OBJECTIVE: To present an analysis of American Academy of Neurology (AAN) membership demographics and practice trends over the past decade. METHODS: Data from the 2009 AAN Census and 2010 Practice Profile Form (PPF) surveys were compared to results from 2004 and 2000 surveys. The Census was sent to all AAN members, and the PPF was sent to a random sample of US practicing neurologists. RESULTS: Since 2000, AAN membership increased by 31%, and the number of US neurologist-members increased by 14%. Mean age of US neurologists increased from 48.6 to 53.3 years, and 23.9% of neurologists are women. There was a 15% increase in the proportion of neurologists relative to the US population, from 3.41 neurologists per 100,000 population in 2000 to 3.92 neurologists in 2009. In 2009, 24.1% of US neurologists were in solo practice, 27.8% were in a neurology group, and 35.6% were in multispecialty/university settings, with little change in practice arrangements over time. The top 5 practice interest areas were unchanged since 2004 as were the number of hours devoted to patient care (42.3) or total work hours per week (57.1). Little change was observed in performed procedures, except increased use of botulinum toxin and nerve blocks and a decline in lumbar punctures. Neurologists rely more on physician assistants to see follow-up and new patients independently (p < 0.001). CONCLUSION: Despite advances in neurologic diagnosis and therapy, there has been little change in practice characteristics of US neurologists.

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.

Cycad exposure and risk of dementia, MCI, and PDC in the Chamorro population of Guam.

OBJECTIVE: To study cycad-derived products as possible risk factors for dementia, mild cognitive impairment (MCI), and parkinsonism-dementia complex (PDC) on Guam. METHODS: Complete risk factor data from in-person interviews of 166 cases of Guam dementia, 50 cases of amnestic MCI, and 21 cases of PDC were compared with 1,581 controls in the base population regarding exposure to cycad-derived products from a traditional food (fadang), consumption of fruit bats, and use of cycad-derived topical medicine. RESULTS: Adjusted odds ratios (ORs) and 95% CIs for picking, processing, and eating fadang in young adulthood ranged from 1.42 (1.05 to 1.91) to 2.87 (1.48 to 5.56) and were consistently elevated and significant across all three diagnostic outcomes. Associations independent of exposure in young adulthood were for picking (OR 0.78, 95% CI 0.64 to 0.96) and processing (OR 0.77, 95% CI 0.63 to 0.94) fadang in childhood with Guam dementia. Men showed stronger and more consistent relations across exposure groups in young adulthood compared with women. No associations were found for consumption of fruit bats or exposure to cycad used as a topical medicine for any of the outcomes. Estimated adjusted population attributable risks suggest that exposure to eating fadang in young adulthood incurred the highest attributable risk percent. CONCLUSIONS: Environmental lifestyle and diet may contribute to the etiology of neurodegenerative diseases in the native population of Guam.

Prevalence of dementia in Chamorros on Guam: relationship to age, gender, education, and APOE.

OBJECTIVES: To estimate the prevalence of dementia and its clinical subtypes among Chamorros on Guam aged 65 years or older and to examine associations with age, gender, education, and APOE genotype. BACKGROUND: Chamorros, the indigenous people of Guam, had a high incidence of ALS and parkinsonism-dementia complex (PDC), in the 1950s. Over the next 50 years, ALS incidence declined markedly, but PDC only slightly. The prevalence of late life dementia in Chamorros and its relationship to ALS/PDC are unknown. METHODS: Island-wide population-based survey of Chamorros aged 65 years or older as of January 1, 2003. Two-stage assessment: cognitive and motor screening, followed by neurologic and psychometric evaluation. Data were reviewed at consensus conference to make clinical diagnoses. RESULTS: Of 2,789 Chamorros aged 65 years or older, 73% were enrolled; 27% declined participation, died before contact or screening, or moved off Guam. The point prevalence of all-cause dementia on February 1, 2004, was 12.2%. Prevalence data for subtypes were as follows: Guam dementia (clinically equivalent to AD), 8.8%; PDC, 1.5%; pure vascular dementia, 1.3%; other, 0.6%. The prevalence of dementia rose exponentially with age. Low education was significantly associated with dementia, but gender was not. There was a trend toward higher PDC prevalence among men. The APOE epsilon4 allele was not associated with dementia. CONCLUSIONS: The prevalence of dementia among elderly Chamorros is relatively high. Guam dementia is the most common diagnosis and exceeds parkinsonism-dementia complex. Age and low education are strongly associated with dementia, but gender and APOE epsilon4 are not. Incidence studies will allow risk factors for dementia to be clarified.

Heart failure in Parkinson's disease: analysis of the United States medicare current beneficiary survey.

OBJECTIVE: We sought to examine the prevalence of heart failure in elderly PD versus non-PD patients using a national sample of Medicare beneficiaries in the United States. SCOPE: The prevalence of heart failure in elderly PD patients was 2.27 times that of non-PD patients (19.4% versus 8.7%, 95% CI = 1.43-3.60, p 0.0005), and remained twice as high after excluding patients with stroke and possible vascular parkinsonism. CONCLUSIONS: In this cross-sectional study of a national Medicare database, heart failure occurred twice as frequently in elderly PD patients as in non-PD patients. Prospective studies are warranted to verify these findings.