Study Finds that Genetics May Determine Mental Response to Exercise

Investigators at the University of Amsterdam, in the Netherlands have found that exercise does not improve anxiety and depression in some individuals, despite conventional wisdom. According to the study, genetics may predict how a person psychologically responds to exercise, though the physical benefits of exercise remain indisputable.

Past studies have repeatedly documented the positive effects of exercise on mood, suggesting that lack of regular leisure-time physical activity contributes to anxiety and depression, as does suddenly stopping exercise.

The researchers conducted cross-sectional and longitudinal studies to determine if there was a causal relationship between exercise and anxiety and depression. They found that exercise does help the conditions, but it wasn’t the exercise itself that was responsible. Rather, the psychological benefits were likely due to common genetic factors. Though identical twins showed no difference in anxiety and depression when one was physically active and the other was not, the same results were not found in fraternal twins. The data also found that increasing exercise during the eleven-year study follow-up also had no effect, nor did stopping exercise when it came to mental health symptoms.

Data for the current study was pooled from 5952 twins from the Netherlands Twin Register, 1357 additional siblings, and 1249 parents, all aged 18 to 50 years. Information surveyed included “leisure-time exercise (metabolic equivalent task hours per week based on type, frequency, and duration of exercise) and four scales of anxious and depressive symptoms (depression, anxiety, somatic anxiety, and neuroticism, plus a composite score)”, conducted between 1991 and 2002.

The researchers note that the findings should be cautiously interpreted. First author Marleen H.M. De Moor, from the University of Amsterdam suggests, "Exercise may help [mental health], but exercise may not help everyone, and certain types of exercise may be better than others."

We may be able to find specific exercises to treat anxiety and depression through further research. Ms. DeMoor says, “It is important to replicate these findings and obtain more insight into when exercise does and does not work to improve mental health outcomes and to determine the types of exercise that might be most beneficial.” Health findings, based on genetics, are always welcome. Research such as this provides much value towards individualized health care.

The study is published in the August issue of the Archives of General Psychiatry.

Arch Gen Psychiatry. 2008;65:955-960. Abstract