The Role of Striatal Dopamine D2/3 Receptor Availability in the Relationship Between Physical Activity and Affective Outcomes

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.