Interventions involving a major dietary component improve cognitive function in cognitively healthy adults: a systematic review and meta-analysis

Abstract

47Accumulating evidence suggests a role for diet in promoting brain health. The purpose of this 48 systematic review was to (i) quantitatively assess whether interventions with a major dietary 49 component can enhance cognition in cognitively healthy adults, and, (ii) identify responsive 50 domains of cognition to inform the design of future dietary trials. Electronic databases were 51 systematically searched to find eligible randomized controlled trials that assessed the effect of 52 interventions with a major dietary component on cognitive function or incident dementia, in 53 adults without known cognitive impairment. Standardized mean differences (SMD) (95% 54 confidence Interval [CI]) were combined using a random-effects meta-analysis and tests of 55 homogeneity of variance were calculated. Two trials reported dementia outcomes and were 56 qualitatively described. Fifteen trials encompassing 6,480 participants were eligible for meta-57 analysis. Compared to control, intervention improved performance on measures of global 58 cognition (SMD=0.14; 95% CI 0.01 to 0.27, P=0.05; I 2 76%), executive function (SMD=0.11; 5995% CI 0.04 to 0.18, P=0.003; I 2 0%) and processing speed (SMD=0.12; 95% CI 0.05 to 0.19, 60 P=0.001; I 2 0%). There was no effect of intervention on delayed memory (SMD=0.04; 95% CI -61 0.02 to 0.09, P=0.18; I 2 4%). Significant heterogeneity and funnel plot asymmetry were detected 62 for global cognition but removal of studies with high risk of bias did not change the pooled 63 findings. Current evidence is limited but indicates that diverse interventions improve non-64 memory cognitive functions during normal cognitive aging. Measures of executive function and 65 processing speed should be considered as feasible end-points in future dietary intervention trials. 66 67

Higher Adherence to the Mediterranean Diet Is Associated With Preserved White Matter Integrity and Altered Structural Connectivity

“…Our results are in line with studies showing that higher adherence to the MedDiet is associated with cognitive scores and white matter integrity (Pelletier et al, 2015;Karstens et al, 2019). As for the cognitive scores, similar to that of McEvoy et al (2019), high MEDAS was associated with executive functioning but not with memory scores. These findings might be related to the age of our cohort as executive functioning appears to decline earlier than other cognitive domains (McEvoy et al, 2019).…”

“…As for the cognitive scores, similar to that of McEvoy et al (2019), high MEDAS was associated with executive functioning but not with memory scores. These findings might be related to the age of our cohort as executive functioning appears to decline earlier than other cognitive domains (McEvoy et al, 2019). Our results also confirm that high adherence to the MedDiet was associated with lower diffusivity values, including MD and RD (Pelletier et al, 2015).…”

In Pursuit of Healthy Aging: Effects of Nutrition on Brain Function

“…A meta-analysis encompassing 15 trials and 6480 participants demonstrated that diet interventions (primarily based on the adoption of a Mediterranean diet) improved performance on measures of global cognition, executive function, and processing speed during normal aging [ 221 ]. This is also supported by a systematic review of the evidence, which indicates that adherence to a Mediterranean diet is associated with better cognitive performance.…”

Z-score neurofeedback, heart rate variability biofeedback, and brain coaching for older adults with memory concerns

“…There is evidence that intervention to reduce some of these risk factors can delay or decrease the risk of age-related cognitive impairment or MCI (McEvoy et al, 2019;Ngandu et al, 2015;Petersen et al, 2014;Williamson et al, 2019). Physical activity is associated with protection from cognitive decline and dementia, and high-intensity exercise is associated with even greater protection (Livingston et al, 2017).…”