May 11, 2000 -- Researchers have found a link between depression and deficiencies of vitamin B-12, which is thought to be essential to proper functioning of our brains and nervous systems. In a study of 700 elderly women, those with vitamin B-12 deficiencies were twice as likely as others to be severely depressed.
"Our most important finding was that vitamin B-12 deficiency and depression are correlated. This is the first proof of this association," says researcher Brenda W.J.H. Penninx, PhD. But Penninx, from the Sticht Center on Aging of Wake Forest University, tells WebMD that researchers cannot be sure whether vitamin B-12 causes depression or vice versa.
A deficiency of either vitamin B-12 or folate can result in neurological and/or psychiatric disease that becomes irreversible if not treated properly, says Penninx, main author of the study published in the American Journal of Psychiatry..
"This connection is supported by findings that psychiatric patients, especially depressed patients, frequently are found to have abnormalities in vitamin B-12 and folate status," Penninx and colleagues write. "However, since the studies thus far have been restricted to psychiatric patients, it is unknown whether vitamin B-12 and folate deficiencies affect depressed mood in the general, community-dwelling population."
The researchers studied 700 disabled, nondemented women aged 65 and older living in the community. They measured their blood levels of vitamin B-12 and folate, and determined their levels of depression. Participants were categorized as having no depression, mild depression, or severe depression.
About one-third of the women were found to be depressed. About 14% were mildly depressed, and 17.4% were severely depressed.
More than 17% of all the women had low levels of vitamin B-12, and those with vitamin B-12 deficiency were twice as likely to be severely depressed as those who were not. Further, women who were either not depressed or were mildly depressed were less likely to be among those who had the deficiency. Folate deficiency was not associated with depression status.
There are a couple of possible explanations for the findings, Penninx says. "The first option is that depressed people are more likely to develop vitamin B-12 deficiency," she says. "This is a very likely explanation. We know depressed people are more likely to have less healthy eating habits. They often eat not often enough, eat fatty foods more often, or are more likely to overeat. ... We don't have any information in this study about food intake."
The other option is that people with vitamin B-12 deficiency are more likely to develop depression. Penninx feels there is no strong evidence for this link.
Jonathan E. Alpert, MD, PhD, of Harvard University, feels differently. "We know that severe B-12 deficiency can lead to neurological symptoms, so it's not implausible to think it can contribute to depression, even though that association hasn't been very strong in previous [studies]," says Alpert, who reviewed the study for WebMD. He notes, however, that the association between the women's actual levels of B-12 and their depression was not very strong in the current study.
Alpert says the study raises the awareness of both physicians and the public that there may be an association between vitamin B-12 levels and depression. "If one is severely depressed, you can have your B-12 levels checked," he says. "However, it won't tell you if taking B-12 would help or change your depression. It tells you that you have a nutritional deficiency that should be corrected."
Noting the 17% incidence of B-12 deficiency in the sample, Penninx agrees. "In this [elderly, disabled] population, depression is common and vitamin B-12 deficiency is common. If there's really a causal link between the two, we should be screening for vitamin B-12 deficiency because it is easily treatable."
Alpert says that the study leaves open some important questions: Would taking vitamin B-12 have prevented the depression, or could it treat the depression? "It's a reasonable speculation," Alpert says.
Says Lon S. Schneider, MD, of the University of Southern California Keck School of Medicine in Los Angeles: "There's absolutely no evidence from the way this study was done that taking vitamin B-12 would prevent depression." What the study does tend to show, he says, is something many physicians already know: that depression in the elderly is often accompanied by other medical problems.
Schneider says that normal doses of vitamins contain enough vitamin B-12 to prevent deficiency, as does a normal diet. People who are deficient in B-12 despite eating well and taking a multivitamin need further evaluation. "Treating B-12 deficiency isn't automatically giving vitamin B-12, because some people may not be able to absorb it," he says.
Alpert says he often recommends that depressed patients take a multivitamin: "One of the core symptoms of depression is that people eat poorly. Often I'll advise people both to try to improve their eating habits in general and take a multivitamin in the hope that will help, along with other treatments. ... It can't hurt."
- New research shows that elderly women who have a vitamin B-12 deficiency are twice as likely to be severely depressed as those without this deficiency.
- People who are depressed often have poor eating habits, so it is difficult to determine whether the vitamin deficiency is a cause or result of depression.
- One expert says he often recommends that his depressed patients try to improve their eating habits and take a multivitamin.