Mediterranean Diet and Age-Related Cognitive Decline: A Randomized Clinical Trial
Valls-Pedret C, Sala-Vila A, et al.
JAMA Internal Medicine. Published online May 11, 2015.
Importance: Oxidative stress and vascular impairment are believed to partly mediate agerelated cognitive decline, a strong risk factor for development of dementia. Epidemiologic studies suggest that a Mediterranean diet, an antioxidant-rich cardioprotective dietary pattern, delays cognitive decline, but clinical trial evidence is lacking.
Objective: To investigate whether a Mediterranean diet supplemented with antioxidantrich
foods influences cognitive function compared with a control diet.
Design, Setting, and Participants: Parallel-group randomized clinical trial of 447 cognitively healthy volunteers from Barcelona, Spain (233 women [52.1percent]; mean age: 66.9 years), at high cardiovascular risk were enrolled into the Prevención con Dieta Mediterránea nutrition intervention trial from Oct. 1, 2003 through Dec.31, 2009. All patients underwent neuropsychological assessment at inclusion and were offered retesting at
the end of the study.
Interventions: Participants were randomly assigned to a Mediterranean diet supplemented with extra virgin olive oil (1 liter per week), a Mediterranean diet supplemented with mixed nuts (30 grams per day) or a control diet (advice to reduce dietary fat).
Main Outcomes and Measures: Rates of cognitive change over time based on a neuropsychological test battery: Mini-Mental State Examination, Rey Auditory Verbal Learning Test (RAVLT), Animals Semantic Fluency, Digit Span subtest from the Wechsler Adult Intelligence Scale, Verbal Paired Associates from the Wechsler Memory Scale and the Color Trail Test were administered. We used mean z scores of change in each test to construct
three cognitive composites: memory, frontal (attention and executive function), and global.
Results: Follow-up cognitive tests were available in 334 participants after intervention (median: 4.1 years). In multivariate analyses adjusted for confounders, participants allocated to a Mediterranean diet plus olive oil scored better on the RAVLT (P = .049) and Color Trail Test part 2 (P = .04) compared with controls; no between-group differences were observed for the other cognitive tests. Similarly adjusted cognitive composites (mean z scores with 95 percent CIs) for changes above baseline of the memory composite were 0.04 (−0.09 to 0.18) for the Mediterranean diet plus olive oil, 0.09 (−0.05 to 0.23; P = .04 versus controls) for the Mediterranean diet plus nuts, and −0.17 (−0.32 to −0.01) for the control diet. Respective changes from baseline of the frontal cognition composite were 0.23 (0.03 to 0.43; P = .003 versus controls), 0.03 (−0.25 to 0.31), and −0.33 (−0.57 to −0.09). Changes from baseline of the global cognition composite were 0.05 (−0.11 to 0.21; P = .005 versus controls) for the Mediterranean diet plus olive oil, −0.05 (−0.27 to 0.18) for the Mediterranean diet plus nuts, and −0.38 (−0.57 to −0.18) for the control diet. All cognitive composites significantly (P < .05) decreased from baseline in controls.
Conclusions and Relevance: In an older population, a Mediterranean diet supplemented with olive oil or nuts is associated with improved cognitive function.
Kevin’s Thoughts: Vascular risk and oxidative stress are important factors that contribute to cognitive impairment with aging. The Mediterranean diet has previously been shown to have a favorable effect on heart health. This study showed that the Mediterranean diet supplemented with olive oil or nuts was also associated with improved cognitive function. An important lesson from this: What is good for the heart is good for the brain. In addition to diet, regular physical exercise, intellectual stimulation, social engagement and engaging in meaningful activities contribute to a healthy brain and can reduce the risk of dementia in later life.
Imaging Correlates of Memory and Concussion History in Retired National Football League Athletes
Strain JF, Womack KB, et al.
JAMA Neurology. 1Center for BrainHealth, School of Behavioral and Brain Sciences, The University
of Texas at Dallas, Dallas 2Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas
3Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas
4Department of Radiology, Johns Hopkins School of Medicine, Baltimore, Maryland Published online May 18, 2015.
Importance: To our knowledge, this is the first study to show an association between concussion, cognition and anatomical structural brain changes across the age spectrum in former National Football League athletes.
Objective: To assess the relationship of hippocampal volume, memory performance and the influence of concussion history in retired National Football League athletes with and without mild cognitive impairment (MCI).
Design, Setting and Participants: This retrospective cohort study assessed differences between groups, mean hippocampal volumes and memory performance by computing age quintiles based on group-specific linear regression models corrected for multiple comparisons for both athletes and control participants. The study was conducted starting in November 2010 and is ongoing at a research center in the northern region of Texas. This current analysis was conducted from Oct. 9, 2013 to Aug. 21, 2014. Participants included 28 retired National Football League athletes, eight of whom had MCI and a history of concussion, 21 cognitively healthy control participants, and six control participants with MCI without concussion.
Main Outcomes and Measures: Hippocampal volume, age, California Verbal Learning Test scores and the number of grade 3 (G3) concussions were assessed. In addition, the number of games played was examined as an objective variable pertaining to football history.
Results: The mean (SD) age was 58.1 (13) years for the 28 former athletes and 59.0 (12) years for the 27 control participants. Retired athletes with concussion history but without cognitive impairment had normal but significantly lower California Verbal Learning Test scores compared with control participants (mean [SD], 52.5 [8] versus 60.24 [7]; P = .002); those with a concussion history and MCI performed worse (mean [SD], 37 [8.62]) compared with both control participants (P < .001) and athletes without memory impairment (P < .001). Among the athletes, 17 had a G3 concussion and 11 did not. Older retired athletes with at least one G3 concussion had significantly smaller bilateral hippocampal volumes compared with control participants at the 40th age percentile (left, P = .04; right, P = .03), 60th percentile (left, P = .009; right, P = .01) and 80th percentile (left, P = .001; right, P = .002) and a smaller right hippocampal volume compared with athletes without a G3 concussion at the 40th percentile (P = .03), 60th percentile (P = .02) and 80th percentile (P = .02). Athletes with a history of G3 concussion were more likely to have MCI (seven of seven) compared with
retired athletes without a history of G3 concussion (one of five) older than 63 years (P = .01). In addition, the left hippocampal volume in retired athletes with MCI and concussion was significantly smaller compared with control participants with MCI (P = .03).
Conclusion and Relevance: Prior concussion that results in loss of consciousness is a risk factor for increased hippocampal atrophy and the development of MCI. In individuals with MCI, hippocampal volume loss appears greater among those with a history of concussion.
Kevin’s Thoughts: Serious head injuries that result in concussions or loss of consciousness are associated with risk for cognitive impairment and dementia. Professional football players are susceptible to such injuries, and this study demonstrated that those who had a history of severe concussions were more likely to have mild cognitive impairment than players without such a history. In addition, those players with MCI and concussion had atrophy (shrinkage) in the hippocampus, the brain area essential to storing memories. An important lessons for those of us who are not football players is to exercise care when participating in activities that
could result in a head injury (e.g., wear seat belts when riding in a car, wear a helmet when bicycling).
Effect of Depression and Diabetes Mellitus on the Risk for Dementia: A National Population-Based Cohort Study
Katon W, Pedersen HS, et al.
JAMA Psychiatry. Published online April 15, 2015.
Importance: Although depression and type 2 diabetes mellitus (DM) may independently increase the risk for dementia, no studies have examined whether the risk for dementia among people with comorbid depression and DM is higher than the sum of each exposure individually.
Objective: To examine the risk for all-cause dementia among persons with depression, DM or both compared with persons with neither exposure.
Design, Setting, and Participants: We performed a national population-based cohort study of 2,454,532 adults, including 477,133 (19.4 percent) with depression, 223,174 (9.1 percent) with DM, and 95,691 (3.9 percent) with both. We included all living Danish citizens 50 years or older who were free of dementia from Jan. 1, 2007 through Dec. 31, 2013 (followed up through Dec. 31, 2013). Dementia was ascertained by physician diagnosis from the Danish National Patient Register or the Danish Psychiatric Central Register and/or by prescription of a cholinesterase inhibitor or memantine hydrochloride from the Danish National Prescription Registry. Depression was ascertained by psychiatrist diagnosis from the Danish Psychiatric Central Research Register or by prescription of an antidepressant from the Danish National Prescription Registry. Diabetes mellitus was identified using the National Diabetes Register.
Main Outcomes and Measures: We estimated the risk for all-cause dementia associated with DM, depression or both using Cox proportional hazards regression models that adjusted for potential confounding factors (e.g., demographics) and potential intermediates (e.g., medical comorbidities).
Results: In total, 418 nursing home residents with indwelling devices were enrolled, with 34 total 174 device-days and 6,557 anatomic sites sampled. Intervention nursing homes had a decrease in the overall MDRO prevalence density. The rate of new methicillin-resistant Staphylococcus aureus acquisitions was lower in the intervention group than in the control group.
Conclusions and Relevance: Depression and DM were independently associated with a greater risk for dementia, and the combined association of both exposures with the risk for
all-cause dementia was stronger than the additive association.
Kevin’s Thoughts: Diabetes and depression are both independent risk factors for dementia in later life. However, previous studies have not examined whether the combination of diabetes and depression in an individual augments that risk. This fascinating study involving more than 2.4 million Danish citizens answers that question and demonstrated that the increase in risk was more than additive — persons with co-occurring diabetes and depression had a 117 percent higher risk for dementia than people with neither condition. The study reinforces the need for better detection and treatment of diabetes and depression.
Dr. Kevin O’Neil is chief medical officer for Brookdale Senior Living® Inc., the largest senior housing provider in the United States. He is board-certified in both Internal Medicine and Geriatric Medicine. O’Neil is a Fellow of the American College of Physicians and a member of the American Geriatrics Society, as well as a member of the American Medical Directors Association and a certified medical director.
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