Physical health and mental health often go hand-in-hand, but it is not always clear which comes first, or which influences the other, or how long the effects last. But, a new study now reports that physical fitness early in life reduces the risk for depression in adulthood.

Swedish researchers evaluated more than 1 million men who enlisted for mandatory military service in Sweden. The men were born between 1950 and 1987 and had no history of mental illness when they were conscripted. The men were followed from 1969 and 2008 to assess their use of healthcare services for depression that required inpatient care. The study was published in the British Journal of Psychiatry.

The men who had low cardiovascular fitness at 18 years of age had a significantly increased risk (almost two-fold) of being hospitalized for depression later in life, compared to those with better physical fitness. The authors conclude that these results strengthen the theory of a cardiovascular component to depression. The mechanism by which exercise affects mental health is not well-defined, but the authors believe that exercise may prevent or reverse the reduced neuronal plasticity (the ability of the brain to change and adapt) that is present in mental health disorders.

Low cardiovascular fitness, independent of overall physical fitness and muscle strength, has previously been implicated in etiologies of mental health disorders, but the studies have been smaller and the results less conclusive that the current study. Low physical fitness is, of course, also associated with obesity, cardiovascular and endocrine diseases, and increased overall mortality. Exercise and increased physical activity can prevent or reverse these physical conditions, but it can also have beneficial effects on mental health. Exercise has even been suggested as a stand-alone therapy for some mental health disorders.

The emphasis of the new study, however, is not on exercise as treatment, but exercise as prevention for depression. Cardiovascular fitness lowered the risk of serious depression for as many as 40 years. The authors hope that the importance of these findings prompts pediatricians and schools to encourage physical fitness among adolescents and teenagers.

Cognitive fitness and intellectual stimulation play a role in the development of mental health disorders, but the brain clearly needs a physically fit body to function at its best.  Exercise is a simple and inexpensive way to encourage all people — especially young people — to maintain a healthy mind and body and improve overall mortality for years to come.

References

Aberg MA, Waern M, Nyberg J, Pedersen NL, Bergh Y, Aberg ND, Nilsson M, Kuhn HG, & Torén K (2012). Cardiovascular fitness in males at age 18 and risk of serious depression in adulthood: Swedish prospective population-based study. The British journal of psychiatry : the journal of mental science PMID: 22700083

Carnethon MR, Gidding SS, Nehgme R, Sidney S, Jacobs DR Jr, & Liu K (2003). Cardiorespiratory fitness in young adulthood and the development of cardiovascular disease risk factors. JAMA : the journal of the American Medical Association, 290 (23), 3092-100 PMID: 14679272

Carter T, Callaghan P, Khalil E, & Morres I (2012). The effectiveness of a preferred intensity exercise programme on the mental health outcomes of young people with depression: a sequential mixed methods evaluation. BMC public health, 12 PMID: 22414319

Church TS, LaMonte MJ, Barlow CE, & Blair SN (2005). Cardiorespiratory fitness and body mass index as predictors of cardiovascular disease mortality among men with diabetes. Archives of internal medicine, 165 (18), 2114-20 PMID: 16217001

Kruisdijk FR, Hendriksen IJ, Tak EC, Beekman AT, & Hopman-Rock M (2012). Effect of running therapy on depression (EFFORT-D). Design of a randomised controlled trial in adult patients [ISRCTN 1894]. BMC public health, 12 PMID: 22260713

Stenman E, Leijon ME, Calling S, Bergmark C, Arvidsson D, Gerdtham UG, Sundquist K, & Ekesbo R (2012). Study protocol: A multi-professional team intervention on physical activity referrals in primary care patients with cardiovascular risk factors–the Dalby lifestyle intervention cohort (DALICO) study. BMC health services research, 12 (1) PMID: 22726659

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