A study published in the journal Alzheimer’s research and therapy describes that the Mediterranean and MIND diets can effectively preserve episodic and visuospatial working memory in midlife.
Study: Diet Patterns and Cognitive Performance in the UK Female Twin Registry (TwinsUK). Image credit: DiViArt/Shutterstock
Age-related cognitive decline is a public health concern because it can affect morbidity and mortality. Although most individuals experience cognitive decline in midlife, the rate of cognitive decline can vary significantly among individuals depending on their cardiovascular health and lifestyle behaviors. A faster-than-normal rate of cognitive decline with age may be a risk factor for Alzheimer’s disease.
Nutrient-rich dietary approaches, such as the Mediterranean (MED) and the Mediterranean-dietary approach to stop hypertension Intervention for neurodegenerative delay (MIND) diet, are known to have neuroprotective and cognitive-enhancing abilities. In this context, evidence indicates that the MED diet may improve cognitive function by positively affecting the gut microbiota.
In this study, scientists investigated the effects of the MED and MIND diets on cognitive function and 10-year changes in cognitive performance in cognitively healthy female twins.
The study analyzed data from the UK Adult Twin Registry which enrolled healthy female twins between 1992 and 2004. A total of 509 female twins who had complete baseline data on diet and cognitive performance between 1998 and 2000 were included in the analysis. Of these twins, 34% were monozygotic (genetically identical) and 66% were dizygotic (50% identical genes).
Baseline dietary intake was assessed using a food frequency questionnaire. Dietary intake data were used to calculate diet scores for the MED and MIND dietary patterns. A higher dietary score indicates higher adherence to the respective diet.
Participants’ cognitive performance was assessed at baseline and ten years later (2008 – 2010). Six types of cognitive functions were tested, including reaction speed, spatial working memory, episodic memory, visual episodic memory, decision time, and visuospatial working memory.
Stool samples were collected from participants at 10-year follow-up for gut microbiota analysis.
Adjusted mean change (SE). Age-related cognition and spatial span length in MZ twins for MIND and MED diet scores over 10 years
Evaluation of the effect of dietary patterns on baseline cognitive performance revealed no significant relationship between MED diet scores and cognitive test scores. For the MIND diet, each 1-point increase in diet score was found to be associated with faster reaction time and better visual episodic memory after adjusting for demographic, health, and lifestyle confounding factors.
Evaluation of the effects of dietary patterns on cognitive performance at 10-year follow-up revealed that increased adherence to the MED or MIND diet was associated with improved episodic memory.
Evaluation of the effect of dietary patterns on 10-year changes in cognitive performance in discordant monozygotic twin pairs revealed that monozygotic twins with higher diet scores generally had less decline in global cognition. However, this difference was not statistically significant.
Within each monozygotic pair, twins with higher MED or MIND diet scores observed greater preservation of visuospatial working memory. This observation was significant for the MED diet. No significant effect of the MED or MIND diet on 10-year changes in other cognitive performance was observed in discordant monozygotic twins.
Regarding the relationship between dietary patterns and gut microbiota, findings revealed that higher adherence to the MIND diet at baseline was associated with higher abundance. Ruminococcaceae UCG-010 (short-chain fatty acid producing bacteria) and low abundance Doria At 10-year follow-up. This association became non-significant after adjusting for dietary fiber intake.
Further analysis shows that a high abundance Ruminococcaceae UCG-010 is associated with reduced global cognition and improved spatial working memory at 10-year follow-up.
Significance of the study
Studies have shown that both MED and MIND diets can effectively preserve episodic and visuospatial working memory in midlife. These neuroprotective effects may be attributed to the high dietary fiber content and the abundance of short-chain fatty acid-producing bacteria in the gut.
As noted by the scientists, the possible influence of unknown genetic factors on the study results of the entire study population cannot be ruled out, because the same pattern of cognitive improvement was not found in monozygotic co-twins.
Future research should include longer follow-up with repeated cognitive assessments to understand the effect of diet on cognitive performance in old age.