Abstract

People living with a non-communicable chronic disease (NCD) are about twice as likely as the general population to suffer from depression. This comorbid condition is associated with several negative consequences, such as worse prognosis and higher risks of mortality. Recent research has examined the beneficial effect of exercise on depressive symptoms and have reported positive results, similar to pharmacotherapy and psychological intervention. However, to date, no study has examined the effect of aerobic exercise on reducing depressive symptoms in NCDs. Moreover, a handful of studies have looked at the association between exercise and depressive symptoms in the asthma population. In order to address these gaps, this thesis systematically reviewed previous literature in the area of aerobic exercise and depressive symptoms in patients with NCDs and explored the association between leisure-time physical activity and depressive symptoms in adults with asthma.

The first study was a systematic review which aimed at assessing the beneficial effects of aerobic exercise on depressive symptoms in a NCD population. A total of 24 studies were included in the meta-analysis. The results revealed a moderate effect of aerobic exercise interventions on depressive symptoms in NCDs in comparison to usual care.

The second study was a cross-sectional study assessing the association between leisure-time physical activity (LTPA) and depressive symptoms in adults with asthma. A total of 953 participants from two asthma cohorts were included. Results revealed that engaging in any LTPA was associated with lower depressive symptoms. Moreover, there was a strong association between engaging in vigorous LTPA and lower depressive symptoms in participants with high levels of depressive symptoms. However, these relationships were no longer meaningful once they were adjusted for inhaled corticosteroid dose and asthma control.

In summary, the research has demonstrated that people with depressive symptoms and a NCD benefit from engaging in aerobic exercise, even at low levels. Given the results of this thesis, practitioners, such as clinical psychologists, may be instrumental in promoting aerobic exercise to clients who depressive symptoms comorbid with a NCD. Further research is needed to better understand the relationship in NCDs, most notable in respiratory diseases and type 2 diabetes.