Relationship Between B-Vitamin Levels and Intake and the Development of Dementia

By 2050, it is predicted that there will be over 115 million people world-wide living with dementia1.  The total estimated cost of dementia worldwide is US$604 billion.1 The related social, economic, and health care challenges will continue to increase as the world population ages and more individuals develop dementia. The debilitative effects of dementia include financial burden, physical and mental disability, dependency, and a decreased quality of life for not only the patient, but the caregiver as well.  The financial and health care implications associated with the staggering increases in incidence predicted for the next 35 years are leading scientists and doctors to seek new factors and treatments to prevent or delay the onset of dementia. There is emerging evidence that modifiable lifestyle and dietary factors may be related to cognitive decline associated with aging.2

In a small population of healthy older adults with a baseline normal cognitive performance, researchers found that lower dietary intake and vitamin B6 blood levels were associated with a greater rate of cognitive decline over a 4-year follow-up period.3 The relationship between cognitive decline and vitamin B6 was not limited to those individuals with a clinical vitamin B6 deficiency, as lower vitamin B6 status included individuals in both the deficient and sufficient range. This suggests optimizing vitamin B6 may be important for cognitive health as one ages. No significant association was observed for dietary intake or plasma levels with cognitive decline for the other B-vitamins (folate, vitamin B12, and riboflavin).

The study population included participants from a previous cross sectional study investigating B-vitamin dietary intakes and biomarker status in the healthy younger and older adults in Northern Ireland. From the previous study population of 662 healthy adults (>age 18 years), those aged >60 years completed a cognitive function test to ensure they could accurately recall food intake.  The present study involved a 4-year follow-up re-examination of those aged >60 in the prior study (n=255). Cognitive function was assessed at baseline and the 4 year follow-up using the Mini-Mental State Examination (MMSE), which is a widely used cognitive test that evaluates attention and concentration, recall and language, orientation, and registration. The MMSE has a maximum score of 30, with a score of <25 indicating a possibility of cognitive impairment, and <20 indicating dementia.4 Dietary intake was assessed using a food frequency questionnaire, as well as a 4-day food diary. The food frequency questionnaire specifically asked for participants to identify the frequency with which they consumed food groups or branded products fortified with B-vitamins, such as cereals, bars, breads, and margarines. Participants were also given a health questionnaire that evaluated their medical and lifestyle history, including depression, use of alcohol and medication, smoking, and educational attainment. Additionally, participants provided a fasting 30mL blood sample and their height and weight was measured at baseline (to calculate their body mass index (kg/m2)).

Of the 255 initially identified participants, 155 were available to participate in the follow-up assessment. At the initial evaluation, 75% of participants were regular consumers of foods fortified with B-vitamins. None of the participants were deficient in vitamin B12 at study inception, but 3% were identified as deficient in folate and 11% in vitamin B6.

The researchers evaluated several lifestyle factors, B-vitamin dietary intake, and B-vitamin biomarker status as determinants of cognitive decline. They found that out of the general health and lifestyle factors they evaluated, only age and baseline MMSE score were predictive of cognitive decline. Also, after adjustment for age and baseline MMSE score, no associations were observed between history of disease (cardiovascular disease, diabetes, and gastrointestinal) or medication use, with the exception of analgesic medication. Vitamin B6 was the only B-vitamin that was found to be predictive of cognitive decline. After adjusting for age and baseline MMSE score, the researchers found that individuals with a lower vitamin B6 level or lower B6 dietary intake were at a 3.5 to 4 fold greater risk for cognitive decline. None of the other B vitamins were associated with a risk of cognitive decline in the study population. The results of this small population study demonstrate value in further research of the role of B-vitamins in a larger cohort of older adults.

  1. Alzheimer’s Society. Demography. https://www.alzheimers.org.uk/site/scripts/documents_info.php?documentID=412 Accessed January 18, 2017.
  2. Bredesen DE. Reversal of cognitive decline: A novel therapeutic program. Aging 2014;6(9):707-717.
  3. Hughes CF, Ward M, Tracey F, Hoey L, Molloy AM, Pentieva K, & McNulty H. B-Vitamin Intake and Biomarker Status in Relation to Cognitive Decline in Healthy Older Adults in a 4-Year Follow-Up Study. Nutrients. January 2017; 9(1):1-14.
  4. Folstein, M.F.; Folstein, S.E.; McHugh, P.R. “Mini-mental state”: A practical method for grading the cognitive state of patients for the clinician. Journal of Psychiatric Research. 1975; 12: 189-198.

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