Vitamin B12 deficiency linked with reduced cognitive function scores
A report published in the December, 2006 issue of the American Journal of Clinical Nutrition revealed the finding of researchers in Great Britain that older individuals with a marker of low vitamin B12 status have reduced cognitive function scores.
The current study included 84 participants in the Welsh cohort of the Medical Research Council’s Cognitive Function and Ageing Study (CFAS), a longitudinal study of men and women aged 65 and older. Stored blood samples were analyzed for vitamin B12, folate, creatinine, holotranscobalamin, which is the amount of vitamin B12 in serum bound to the transport protein transcobalamin, and methylmalonic acid, a compound that increases in vitamin B12 deficiency. The subjects completed the Mini-Mental State Examination and the Cognitive Section of the Cambridge Mental Disorders of the Elderly Examination (CAMCOG), which tested orientation, language, attention, memory, praxis, calculation, abstract thinking and perception.
Forty-three percent of the study population was determined to have “likely metabolically significant vitamin B12 deficiency.” Not surprisingly, high methylmalonic acid concentrations were correlated with low levels of vitamin B12 and holotranscobalamin. Although none of the participants had dementia, 31 percent had test scores indicative of cognitive impairment. Having higher methylmalonic acid concentrations was correlated with worse Mini-Mental State Examination Scores and lower scores in the CAMCOG examination in the areas of language comprehension and expression, and ideational praxis. Deficient folate levels were less prevalent and had weak correlations with lower test scores in several areas.
In an accompanying editorial, Joshua W. Miller of the University of California, Davis notes that only a few studies have assessed the associations between methylmalonic acid, holotranscobalamin and cognitive function. In the current study, only methylmalonic acid was found to be associated with cognitive function scores. “These results suggest that methylmalonic acid better reflects vitamin B12 status and is a better predictor of cognitive function in older adults than is total vitamin B12 or holotranscobalamin,” he writes. However, since inconsistent results have also been found to be associated with methylmalonic acid, some researchers have proposed screening tests for vitamin B12 deficiency that analyze a combination of factors. “The challenge now for investigators is to use these multiple analyte strategies in cohort studies to determine whether they improve the ability to predict cognitive deficits in older adults,” he concludes.
Screening for cognitive changes should be done even before overt changes in cognitive ability are apparent so that diet and lifestyle changes, as well as supplementation, can be started early.
The test most often used to evaluate memory and cognitive function is the Mini-Mental Status Examination, which tests multiple aspects of cognitive function, including orientation to time, place, and person; memory; verbal and mathematical abilities; judgment; and reasoning. In elderly patients, the clinician should differentiate early-stage dementia from normal age-associated memory impairment. People with memory impairment have a relative deficiency in recall compared with others their age. They also tend to learn new information more slowly, but if they are given extra time for such tasks, their intellectual performance is usually adequate.
Vitamins are involved in biochemical processes throughout the body and appear to be involved in protecting and enhancing cognitive function. In particular, the B vitamins play an integral role in the functioning of the nervous system and help the brain synthesize chemicals that affect mood. A balanced complex of the B vitamins is essential for energy and for balancing hormone levels. An article in the Journal of Psychopharmacology described a study of 76 older men who were given vitamin B6 or placebo and then tested on memory function. The authors concluded that vitamin B6 improved storage and information retrieval (Deijen JB et al 1992). Another study reviewed vitamin B12 deficiency in relation to memory impairment and neuropathy in older people and concluded that both memory impairment and neuropathy can be successfully managed with vitamin B12 injections or supplementation (Carmel R 1996). One study determined that low levels of folate (a B vitamin) are associated with cognitive deficits and that patients treated with folic acid for 60 days showed a significant improvement in both memory and attention efficiency (Fioravanti MFE 1997).
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