Study Debunks link Between Physical Activity and Depression in Adolescents

A latest study knocks the popular belief that physical exercise helps lower the risk of depression stating there is no association between the two factors.

Depression, a mood disorder, is estimated to affect 19 million American adults. This serious common medical illness involves the brain and is known to affect a person's thoughts, behavior, feelings as well as the sense of well-being. Studies have shown that depression can be helped by adhering to regular exercise.

It was previously believed that physical activity stimulated the brain's pleasure centres and led to feelings of well-being.

But in the latest study, researchers at the University of Cambridge, U.K., found that there is no significant association between physical activity and symptoms of depression in adolescents. But, the evidence is not clear-cut.

Depression is known to contribute to the global burden of disease. A drop in the costs associated with the mental illness - both personal and financial - benefit the society. The onset of depression is known to occur in adolescence and earlier preventive measures taken during this phase could prove to be beneficial.

In this longitudinal study, the researchers focused on 736 participants with an average age of 14.5 years. The study was conducted from 2005-2010. The participants were followed for three years after the baseline. They measured the physical activity expenditure and levels of moderate and vigorous physical activity.

The measures of physical activity were further broken into weekday and weekend activity. Using a self-reported questionnaire, the researchers measured mood symptoms. Apart from this, an interview was conducted at baseline and three years later.

The researchers found no link between the levels of PA at 14 years of age and depressive outcomes at 17 years of age.

"Our findings do not eliminate the possibility that PA positively affects depressed mood in the general population; rather, we suggest that this effect may be small or nonexistent during the period of adolescence. Our findings carry important public policy implications because they help to clarify the effect of PA on depressive symptoms in the general population. Although PA has numerous benefits to physical health in later life, such positive effects may not be expected on depressive outcomes during adolescence," authors explain.

The finding was documented in the journal JAMA Pediatrics.