Folic acid: do supplements prevent dementia?

Deficiency of folate, derivatives of vitamin B 9, is very common among postmenopausal women and appears to increase the risk of dementia or mild cognitive impairment, a form of predementia. Folic acid supplements could therefore play an important role in protecting against cognitive decline.

This was reported in a study conducted by researchers from the Department of Epidemiology at Columbia University in New York, USA, and published in the Journal of the Academy of Nutrition and Dietetics.

B vitamins and dementia

B vitamins are critical for the functioning of several enzymes involved in cell metabolism. The role of these vitamins, especially B6, B12 and folate, in protecting cognitive function in the elderly has been under study for some years. Several researches have shown that a higher intake of B vitamins may be associated with a lower risk of dementia. Dementia is defined as a condition of chronic and progressive dysfunction of brain function that leads to a decline in a person's cognitive faculties. Mild Cognitive Impairment, on the other hand, indicates the transition phase between normal aging and dementia.

Folate deficiency increases risk of dementia

This research, conducted as part of a clinical trial, the Women's Health Initiative Memory Study, involved more than 7,000 postmenopausal women whose nutritional intake of B vitamins was assessed in relation to the possible development of cognitive disorders. Participants were contacted between 1993 and 1998, and their intake of B vitamins was assessed through a food consumption frequency questionnaire. Levels of folate, vitamin B6, and vitamin B12 and their association, alone or in combination, with dementia of varying severity were thus identified. 

It emerged from the results that 46.7 percent of the women examined were taking daily levels of folate below the recommended intake (400 µg). In contrast, vitamin B6 was found to be deficient in about 27 percent of the women, while only 2.5 percent showed insufficient levels of vitamin B12. Deficiencies appeared to be associated with greater sedentary lifestyle and poorer socioeconomic conditions. During the 5-year observation period, a total of 307 cases of dementia or Mild Cognitive Impairment were diagnosed, 16.4 percent of which had evolved into probable dementia by the end of the observation period. The 'incidence of Mild Cognitive Impairment and dementia was higher among women with folate insufficiency, with an increased risk of about 100% for women with intake levels below the daily requirement. No correlation, however, emerged for vitamin B6 intakes below recommended levels.

A relationship to be confirmed

Intake of folate below the recommended daily intake appears to increase the risk of dementia in old age. In light of these observations, the study authors hypothesize that folate supplements might help prevent cognitive decline in the elderly population. However, further study of this hypothesis is needed.   

Source: Agnew-Blais JC, Wassertheil-Smoller S, Kang JH, Hogan PE, Coker LH, Snetselaar LG, Smoller JW. "Folate, Vitamin B-6, and Vitamin B-12 Intake and Mild Cognitive Impairment and Probable Dementia in the Women's Health Initiative Memory Study. "J Acad Nutr Diet. 2014 Sep 5. pii: S2212-2672(14)01056-9. doi: 10.1016/j.jand.2014.07.006.