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Accumulating evidence suggests a role for diet in promoting brain health. The purpose of this systematic review was to (1) quantitatively assess whether interventions with a major dietary component can enhance cognition in cognitively healthy adults and (2) identify responsive domains of cognition to inform the design of future dietary trials. Electronic databases were systematically searched to find eligible randomized controlled trials that assessed the effect of interventions with a major dietary component on cognitive function or incident dementia in adults without known cognitive impairment. Standardized mean differences (SMDs) (95% confidence interval [CI]) were combined using a random-effects meta-analysis, and tests of homogeneity of variance were calculated. Two trials reported dementia outcomes and were qualitatively described. Fifteen trials encompassing 6480 participants were eligible for meta-analysis. Compared to control, intervention improved performance on measures of global cognition (SMD = 0.14, 95% CI 0.01-0.27, P = .05, I2 76%), executive function (SMD = 0.11, 95% CI 0.04-0.18, P = .003, I2 0%), and processing speed (SMD = 0.12, 95% CI 0.05-0.19, P = .001, I2 0%). There was no effect of intervention on delayed memory (SMD = 0.04, 95% CI -0.02 to 0.09, P = .18, I2 4%). Significant heterogeneity and funnel plot asymmetry were detected for global cognition, but removal of studies with high risk of bias did not change the pooled findings. Current evidence is limited but indicates that diverse interventions improve nonmemory cognitive functions during normal cognitive aging. Measures of executive function and processing speed should be considered as feasible end points in future dietary intervention trials.

Unimpaired cognition is an important feature of successful aging. Differences in cognitive performance among healthy older adults may be related to differences in brain structure. The authors reviewed the literature to examine the relationship between brain-structure size and cognitive performance in older adults. Eighty-three percent of studies found at least one positive relationship between these factors; however, findings were variable. Positive relationships emerged most consistently between the hippocampal formation and global cognition and memory and between frontal measures and executive function. Additional longitudinal study is needed to further evaluate structure-cognition relationships in older adulthood and across the adult lifespan.

A well-studied index of reasoning and decision making is the Iowa Gambling Task (IGT). The IGT possesses many features important to medical decision making, such as weighing risks and benefits, dealing with unknown outcomes, and making decisions under uncertainty.There exists a great deal of individual variability on the IGT, particularly among older adults, and the present study examines the role of personality in IGT performance. We explored which of the five-factor model of personality traits were predictive of decision-making performance, after controlling for relevant demographic variables.One hundred and fifty-two healthy cognitively intact adults (aged 26-85) were individually administered the IGT and the NEO Five-Factory Inventory.In the older adults, but not the younger, higher NEO neuroticism was associated with poorer IGT performance.Our findings are discussed in the context of how stress may impact cognitive performance and cause dysfunction of neural systems in the brain important for decision making.

Objective: To investigate the differences in the relationship of age to brain function among individuals with schizophrenia and a healthy comparison group. The authors hypothesized that the correlation with age would be more strongly negative among schizophrenia patients, particularly in the frontal cortex. Design: Cross-sectional measures of functional MRI (fMRI) brain response were correlated with age in both groups. Setting: Participants came to university research facilities for testing. Participants: The authors analyzed data from 30 patients with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition schizophrenia or schizoaffective disorder ranging in age from 25 to 68 years and 14 healthy comparison participants ranging in age from 21 to 70 years. Measurements: Brain response during word pair learning was measured with fMRI in each voxel of the brain. This measure was correlated with age within each group and the correlations were compared across groups in regions of interest determined a priori and based on a whole-brain analysis. In exploratory analyses, the authors examined the interaction of task performance with age and study group. Results: The correlations between age and brain response were more positive in the healthy group than in the schizophrenia group in several regions, including right lateral prefrontal cortex and clusters in midline precuneus and right superior temporal gyrus. Interactions with task performance suggest that age effects on brain function relate differently to cognitive output in patients and comparison participants. Conclusions: There is no strong evidence that functional brain response during learning changes significantly with age among schizophrenia patients, in contrast to findings of positive associations with age among healthy individuals.