MDD: Predictors and Protectors

1. Regular Exercise of Any Intensity for as Little as 1 Hour per Week Can Protect Against Future Depression: A healthy cohort of 33,908 Norwegian adults who had no symptoms of common mental disorders or limiting physical conditions was asked at baseline to report the frequency of exercise they participated in and at what intensity. They were monitored over 11 years. After adjusting for confounders, 12% of future cases of depression could have been prevented if all participants had engaged in at least 1 hour of physical activity each week.[1]

Clinical Implications for Study 1: “We’ve known for some time that exercise has a role to play in treating symptoms of depression, but this is the first time we have been able to quantify the preventative potential of physical activity in terms of reducing future levels of depression,” said lead author Samuel Harvey, Associate Professor at the University of New South Wales in Australia. “These results highlight the great potential to integrate exercise into individual mental health plans and broader public health campaigns. If we can find ways to increase the population’s level of physical activity even by a small amount, then this is likely to bring substantial physical and mental health benefits.”

2. Childhood Sexual Abuse (CSA) Among Men Can Lead to Depression Into Old Age, Although Social Support Appears to Mitigate These Deleterious Effects: An analysis used data from the Wisconsin Longitudinal Study of men and women who had graduated from high school in Wisconsin in 1957, including a subset of 2451 men. A group of 129 men who reported CSA were compared with a randomly sampled, matched control group of 2332 men with no such reported history. After adjustment for demographic, family, and health factors, the CSA group had higher statistically modeled levels of depressive symptoms than the control group at each time juncture into old age, which signified a noticeable clinical effect.[2]

Clinical Implications for Study 2: “CSA and childhood adversities should be included in clinical assessments with older men. Scholarship is needed to identify the most effective means of gathering sensitive information from men in their 50s and older-and delivering services that alleviate psychological suffering in this population,” stated the researchers, led by Scott Easton, PhD, of the School of Social Work at Boston College.

3. Men Who Eat a Vegetarian Diet May Be at Greater Risk for Depression Than Men Who Eat Meat: In an observational study that included 9668 men, 350 men reported being vegetarians or vegans. The vegetarian/vegan group had higher depression scores on average than non-vegetarians and a greater risk of mild to moderate depression than non-vegetarians after adjustment for potential confounding factors.[3] Nutritional deficiencies (for example, cobalamin or iron) are a possible explanation for these findings; however, reverse causation could not be ruled out.

Clinical Implications for Study 3: “To our knowledge this is the first large epidemiological study to show a relationship between vegetarianism and significant depressive symptoms among adult men,” stated the researchers, led by Joseph R. Hibbeln, MD, acting chief of the Section on Nutritional Neurosciences at the National Institute on Alcohol Abuse and Alcoholism. “Since exclusion of red meat primarily characterizes vegetarians, lower intakes of vitamin B12 merit consideration as a contributing factor” that may lead to depression. He recommended ensuring vegetarian men have a good vitamin B12 status.