August 2009

Folate and Depression
L-methylfolate (Deplin) shows theoretical promise as an augmenting strategy for treatment-resistant depression, but so far there is little clinical evidence of its efficacy.

Breast Cancer, Tamoxifen, and 2D6 Inhibitors
Antidepressants and other drugs that inhibit the cytochrome P450 2D6 isoenzyme may cause low levels of tamoxifen in women with breast cancer.

In Brief
Lithium in Drinking Water May Decrease Suicide Risk; No Association Found Between Fish Consumption and Dementia

Treating Depression in Parkinson's Disease
Two studies provide preliminary but encouraging data about nortriptyline and omega-3 fatty acids as potential treatments for depression in patients with Parkinson's disease.

In Brief

August 2009

Lithium appears to have an antisuicidal effect in people with mood disorders (BTP 2004;27:1-2). A 1990 study suggested that the presence of low levels of lithium in drinking water might have decreased the risk of suicide in Texas. A recent study has replicated these findings (Ohgami H, et al. Br J Psychiatry 2009;194:464-465). In 2006, investigators found that lithium levels in drinking water in the 18 municipalities of the Oita prefecture in Japan ranged from 0.7 to 59 µg/L. The average standardized mortality ratios of suicide (observed deaths divided by expected deaths compared with gender- and age-matched general population) across the municipalities were significantly and negatively associated with lithium levels (P < .004). In an editorial accompanying this report, Dr Allan Young suggests that these findings merit follow-up with research into lithium's effect on brain function and the mechanism of its purported antisuicide effect, followed by large-scale trials involving the addition of lithium to drinking water supplies (Br J Psychiatry 2009;194:466). He states that the "eventual benefits for community mental health may be considerable."

Studies of the effect of omega-3 polyunsaturated fatty acid (PUFA) intake on the risk of dementia have been inconclusive. Two recent such projects were negative. Devore and others studied consumption of fish and omega-3 PUFAs in relation to long-term dementia risk in 5395 participants aged 55 years or older (Am J Clin Nutr 2009;90:170-176). They evaluated dementia and Alzheimer's disease (AD) risk across categories of typical fish intake (none, low, and high) as well as fish type consumed (none, lean, and fatty). They also evaluated dementia and AD risk across tertiles of omega-3 PUFA intake, including eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA), alpha-linolenic acid, and EPA and DHA individually. Over an average follow-up of 9.6 years, dementia developed in 465 participants (365 of whom were diagnosed with AD). Neither total fish intake nor dietary intake of omega-3 PUFAs was related to dementia risk or risk of AD. Subjects with a high fish intake and those who ate fatty fish had a similar dementia risk to those who ate no fish. In the second study, Kroger et al found no association between erythrocyte membrane total omega-3 PUFAs, DHA, or EPA and the incidence of dementia or AD in 663 subjects aged 65 years or older (Am J Clin Nutr 2009;90:184-192). So far, the hope that fish intake and omega-3 fatty acids could protect against AD does not appear to be supported by science.

Heather S. Hopkins