Major Depressive Disorder (MDD) is estimated to affect approximately 350 million people (Dipnall et al., 2016). Selective Serotonin Reuptake Inhibitors (SSRIs) are the most commonly prescribed (61.7% of antidepressant prescriptions) medication to treat MDD (Alhulwah et al., 2011). The exact mechanism for SSRIs alleviation of depressive symptoms remains to be determined, however a current theory hypothesise that SSRIs affect brain homeostasis resulting in the down regulation and upregulation of specific serotonin transmitters in different regions of the brain (Santarsieri and Schwartz, 2015). SSRIs result in common side-effects such as nausea, vomiting, insomnia, drowsiness, headache, decreased sex drive, and agitation have been observed (Edinoff et al., 2021). Increased physical activity exercise has been shown to aid in the treatment of MDD, and may provide additional benefits in addition to SSRIs (Singh et al., 2023). Whether SSRIs affect physical activity levels is yet to be systematically investigated in the literature. This study will aim to systematically review the available literature to investigate whether the initiation of SSRI medication impacts physical activity levels and will also aim to quantify the this effect via meta-analysis. The search criteria will aim to include any studies which report physical activity levels prior to, and following the initiation of SSRI medication in human participants. The primary measures of effect will be standardised mean difference of physical activity levels at pre and post SSRI intervention. It is hypothesised that SSRI medication significantly affects physical activity levels in patients with MDD.
