Abstract
Regular exercise has been associated with improvements in well-being, yet the neurobiological mechanisms underlying these effects remain unclear. The present study examined whether striatal dopamine D2/3 receptor availability is related to affective symptoms and whether it moderates the relationship between activity levels and affect. Thirty-one healthy older adults completed retrospective self-report measures of physical activity and affective symptoms and underwent positron emission tomography (PET) imaging with [11C]Raclopride to assess D2/3 receptor availability in the dorsal caudate, dorsal putamen, and ventral striatum. Results showed a significant interaction between physical activity and ventral striatal D2/3 receptor availability, such that the association between physical activity and composite distress was more strongly negative at lower levels of ventral striatal D2/3 receptor availability and attenuated at higher levels. No interactions were observed in the dorsal putamen or dorsal caudate. Self-reported physical activity was not significantly related to affective symptoms at the between-person level. However, lower D2/3 receptor availability in the dorsal caudate was associated with greater general distress and worry, with no corresponding associations observed in the dorsal putamen or ventral striatum.
Complementary ecological momentary assessment (EMA) analyses in an independent sample (N = 177) indicated that higher daily physical activity (measured using Oura rings) was associated with increased positive mood and reduced negative mood at the within-person level. In addition, lower dorsal caudate dopamine synthesis capacity [18F]fluoro-m-tyrosine was associated with stronger within-person increases in positive mood on more physically active days.
Overall, the findings of this study suggest that dopaminergic function and physical activity are both related to affective outcomes across individuals and in daily life.