Mediterranean and Western diet effects on Alzheimer's disease biomarkers, cerebral perfusion, and cognition in mid-life: A randomized trial.

INTRODUCTION: Mid-life dietary patterns are associated with Alzheimer's disease (AD) risk, although few controlled trials have been conducted. METHODS: Eighty-seven participants (age range: 45 to 65) with normal cognition (NC, n = 56) or mild cognitive impairment (MCI, n = 31) received isocaloric diets high or low in saturated fat, glycemic index, and sodium (Western-like/West-diet vs. Mediterranean-like/Med-diet) for 4 weeks. Diet effects on cerebrospinal fluid (CSF) biomarkers, cognition, and cerebral perfusion were assessed to determine whether responses differed by cognitive status. RESULTS: CSF amyloid beta (Aß)42/40 ratios increased following the Med-diet, and decreased after West-diet for NC adults, whereas the MCI group showed the reverse pattern. For the MCI group, the West-diet reduced and the Med-diet increased total tau (t-tau), whereas CSF Aß42 /t-tau ratios increased following the West-diet and decreased following the Med-diet. For NC participants, the Med-diet increased and the West-diet decreased cerebral perfusion. DISCUSSION: Diet response during middle age may highlight early pathophysiological processes that increase AD risk.

Ketogenic dietary lifestyle intervention effects on sleep, cognition, and behavior in mild cognitive impairment: Study design.

Introduction: Sleep and diet are modifiable risk factors for Alzheimer's disease (AD) that may be salient areas for the development of preventive intervention strategies against dementia in people with mild cognitive impairment (MCI). Sleep disturbances account for up to 15% of the population attributable risk for AD. Diet influences sleep quality, such that diets high in sugars, fat, and processed food affect sleep quality and cognition in older adults. The combination of poor sleep and diet health may increase risk for dementia in people with MCI, yet it is unknown how intervening on diet may influence sleep health. Methods: The MCI Sleep Study assesses longitudinal changes in objective and subjective measures of sleep between two investigational diet groups in the Brain Energy for Amyloid Transformation in Alzheimer's Disease study: the modified Mediterranean ketogenic diet (MMKD) and the American Heart Association diet. Objective sleep assessments include an in-home sleep study using the WatchPAT Central Plus (Itamar Medical, Ltd) at baseline and the end of the 4-month diet intervention. Subjective sleep questionnaires include the Epworth Sleepiness Scale and Pittsburgh Sleep Quality Index. The MCI Sleep Study outcome measures include longitudinal change in cognitive performance, mood, behavior, and quality of life. Results: Study recruitment is currently ongoing. We hypothesize the low-carb MMKD diet to have a beneficial impact on sleep health in individuals with MCI. Pre- and post-diet changes in sleep metrics across diet groups will be examined using mixed effects analysis of variance models. Discussion: Early assessment of chronic sleep and diet behaviors may be vital in understanding when interventions are necessary and the lifestyle modifications that should accompany future AD prevention and therapy recommendations.

Metabolic Syndrome and Neurocognition Among Diverse Middle-Aged and Older Hispanics/Latinos: HCHS/SOL Results.

OBJECTIVE: Hispanics/Latinos have the highest risks for metabolic syndrome (MetS) in the U.S. and are also at increased risk for Alzheimer disease. In this study, we examined associations among neurocognitive function, MetS, and inflammation among diverse middle-aged and older Hispanics/Latinos. RESEARCH DESIGN AND METHODS: Cross-sectional data (2008-2011) from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) were analyzed to examine associations between neurocognition and MetS among diverse Hispanics/Latinos (N = 9,136; aged 45-74 years). RESULTS: MetS status was associated with lower global neurocognition, mental status, verbal learning and memory, verbal fluency, and executive function. Age significantly modified the associations between MetS and learning and memory measures. Significant associations between MetS and neurocognition were observed among middle-aged Hispanics/Latinos, and all associations remained robust to additional covariates adjustment. CONCLUSIONS: We found that MetS was associated with lower neurocognitive function, particularly in midlife. Our findings support and extend current hypotheses that midlife may be a particularly vulnerable developmental period for unhealthy neurocognitive aging.

Obesity and Co-morbid Conditions Are Associated with Specific Neuropsychiatric Symptoms in Mild Cognitive Impairment.

Background: Neuropsychiatric symptoms (NPSs) in MCI, and midlife obesity increase the likelihood of developing Alzheimer's disease. It is unknown whether obesity or related health conditions modify the risk of NPS or severity of cognitive impairment in MCI. Methods: One hundred and thirteen subjects with MCI were assessed near the time of MCI diagnosis. The sample was divided by BMI and related disorders, type-2 diabetes (T2D) and obstructive sleep apnea (OSA) to measure the relationship of these groups with NPS and severity of MCI. NPSs scores were evaluated based on the Neuropsychiatric Inventory-Questionnaire (NPI-Q) and Geriatric Depression Scale, along with NPI-Q clusters. MCI-severity was estimated based on a composite z-score of neuropsychological tests. Results: Obese and overweight subjects represented 65% of the sample and were on average 7 years younger than normal weight subjects. The presence of obesity, T2D and OSA status modified the prevalence and severity of specific NPI-Q symptom clusters, specifically affective symptoms were more frequent across groups and severe in OB and T2D. Total NPS scores were higher for subjects with T2D and OSA although MCI-severity did not differ across groups. Conclusion: MCI subjects with obesity, T2D and OSA demonstrated a higher susceptibility to psychopathologic changes.

Corrigendum: Obesity and Co-morbid Conditions Are Associated with Specific Neuropsychiatric Symptoms in Mild Cognitive Impairment.

[This corrects the article on p. 164 in vol. 9, PMID: 28611655.].