B-vitamin intake in younger adulthood and association with middle-age cognitive function.
In an ageing population, the global burden of cognitive impairment and dementia is significant and identifying potentially preventative lifestyle and dietary behaviours is of great interest. Evidence suggests that cognitive decline may already be evident by middle age, indicating a possibility that the critical period for preventative strategies against dementia may be earlier than predicted. Few studies have evaluated the association of B-vitamin intake in young adulthood with cognitive function in later life. Accordingly, the authors of the present study aimed to assess associations of niacin, folate, vitamin B-6, and vitamin B-12 intake in younger adulthood with cognitive function in midlife.
The CARDIA (Coronary Artery Risk Development in Young Adults) study was a community-based, multicentre, longitudinal study of 5115 men and women from across the United States of America, aged 18-30 years that commenced in 1985-86 (baseline year 0). Participants were re-examined during 7 follow-ups at years 2, 5, 7, 10,15, 20, and 25. For the present study, the authors used data for participants who had undergone cognitive measurements at year 25 and who had at least one measurement of B-vitamin intake at either baseline, year 7, or year 20. Dietary intake, including dietary and supplemental B-vitamins, was assessed though an interviewer-administered dietary questionnaire with nutritional intake assessed based on the Nutrition Data System for Research database. In participants who had multiple dietary assessments, mean total intake was used to reflect long-term intake. Cognitive function was assessed at the 25-year follow-up through the use of the Rey Auditory Verbal Learning Test (RAVLT) for verbal memory, the Digit Symbol Substitution Test (DSST) for psychomotor speed, and a modified Stroop interference test for Stroop interference test for executive function.
From the 5115 participants recruited in the CARDIA study, dietary data and cognitive function assessments were available for 3136 participants. Of these participants, 55% were white, 56% were female, and had a mean age of 25.1 years at baseline. Participants with a higher intake of niacin, folate, B-6 or B-12 were older, more likely to be female and white, exercised more, and had a higher education level. The study found when comparing the highest intake with the lowest quintiles, cumulative total intake of niacin was significantly associated with improved DSST and Stroop tests. Total folate was associated with improvement on the DSST scores. Higher intakes of vitamin B-6 and B-12 were both associated with improved psychomotor speed as measured by the DSST scores when comparing the highest and lowest intake quintiles.
Strengths of the study include the long term follow up periods and dietary assessments across a number of time points. The authors identified and adjusted for potential modifiers in analysing the results. The study is limited by cognitive function being assessed only once, thus not providing a baseline level to assess and evaluate changes in cognitive function and decline from. Estimated dietary and supplemental intake through recall questionnaires remains a challenge to accurately capture intake. Furthermore, identifying an association between individual vitamins remains difficult due to the high correlation between B-vitamins.
The study provides some interesting results and points for consideration. As previously highlighted, if early stages of cognitive decline are evident in middle age, then potentially the time to employ preventative strategies against cognitive decline and dementia is prior to this. The study provides an evaluation of this time course finding that higher intakes of B-vitamins from both food and supplemental sources may be associated with better cognitive performance in middle age, especially for psychosocial speed. Further studies are required to better understand this better as are longer term CARDIA follow ups to identify and assess the ongoing effects of B vitamin intake and cognitive function.
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|Publication:||Australian Journal of Herbal Medicine|
|Date:||Mar 1, 2018|
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