Brenda Penninx, Ph.D., and colleagues from The Johns Hopkins University, the University of Colorado in Denver and Vrije University in the Netherlands have found a positive correlation between vitamin B12 (cobalamin) deficiency and depression in physically disabled elderly women. Data from the Women’s Health and Aging Study were used to assess the link between vitamin B12 levels, folate levels and depression in 700 community-dwelling, physically disabled women ages 65 and over with no severe cognitive impairment.
Both vitamin B12 and folate are essential for several metabolic pathways in the central nervous system, and abnormal vitamin B12 and folate levels have been found in psychiatric patients. The researchers wanted to see if the same correlation was found within the general community as well.
All 700 women scored 18 or higher on the Mini-Mental State Examination and reported difficulty in performing tasks in at least two of four areas: mobility, upper-extremity abilities, higher-function tasks of independence and basic self-care. An in-home comprehensive exam was done of all subjects, and a blood sample was taken to determine possible vitamin B12 deficiency.
Since low serum levels are not specific in diagnosing tissue deficiency, high levels of two metabolites of vitamin-dependent conversions-in combination with low serum vitamin B12 and folate levels-were used to determine tissue vitamin deficiency. Vitamin B12 deficiency was determined by either a high or low cutoff, in order to evaluate any dose-response relationships. The high cutoff was a serum B12 level of less than 258 pmol/liter; a low cutoff was a serum B12 level of less than 148 pmol/liter. Folate deficiency was determined as a serum folate level less than 11.4 nmol/liter and a homocysteine level higher than 13.9 pmol/liter.
Depressive symptoms were scored according to the Geriatric Depression Scale. A score lower than 9 indicated no depression, subjects with mild depression scored from 10 to 13, and those with severe depression scored 14 or higher.
Of the 700 participants, 478 (68.3%) were not depressed, 100 (14.3) had mild depression, and 122 (17.4%) had severe depression. Prevalence of vitamin B12 deficiency was 17.3% (n=121) at the higher cutoff and 4.6% (n=32) at the lower cutoff. Folate deficiency was found in 7.1% (n=50) of all subjects.
Vitamin B12 deficiency (scored at either high or low cutoff) was present significantly more often among depressed subjects than among controls. No associations with vitamin B12 deficiency were found for mild depression, but the risk of severe depression was twice as high in women with vitamin B12 deficiency as in controls (odds ratios of 2.05 and 2.09 for high and low cutoffs, respectively). Folate deficiency was not associated with depression status.
The researchers summarized by stating, “Clinicians and other health care providers need to be aware of the high prevalence of vitamin B12 deficiency in disabled older women, and they need to screen and treat appropriately”.