AUTHOR=Simonsson Emma , Stiernman Lars Jonasson , Lundquist Anders , Rosendahl Erik , Hedlund Mattias , Lindelöf Nina , Boraxbekk Carl-Johan 

TITLE=Dopamine D2/3-receptor availability and its association with autonomous motivation to exercise in older adults: An exploratory [11C]-raclopride study

JOURNAL=Frontiers in Human Neuroscience

VOLUME=16

YEAR=2022

URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2022.997131

DOI=10.3389/fnhum.2022.997131

ISSN=1662-5161

ABSTRACT=<sec><title>Background</title><p>Autonomous motivation to exercise occurs when the activity is voluntary and with a perceived inherent satisfaction from the activity itself. It has been suggested that autonomous motivation is related to striatal dopamine D2/3-receptor (D2/3R) availability within the brain. In this study, we hypothesized that D2/3R availability in three striatal regions (nucleus accumbens, caudate nucleus, and putamen) would be positively associated with self-reported autonomous motivation to exercise. We also examined this relationship with additional exploratory analyses across a set of <italic>a priori</italic> extrastriatal regions of interest (ROI).</p></sec><sec><title>Methods</title><p>Our sample comprised 49 older adults (28 females) between 64 and 78 years of age. The D2/3R availability was quantified from positron emission tomography using the non-displaceable binding potential of [<sup>11</sup>C]-raclopride ligand. The exercise-related autonomous motivation was assessed with the Swedish version of the Behavioral Regulations in Exercise Questionnaire-2.</p></sec><sec><title>Results</title><p>No significant associations were observed between self-reported autonomous motivation to exercise and D2/3R availability within the striatum (nucleus accumbens, caudate nucleus, and putamen) using semi-partial correlations controlling for ROI volume on D2/3R availability. For exploratory analyses, positive associations were observed for the superior (<italic>r</italic> = 0.289, <italic>p</italic> = 0.023) and middle frontal gyrus (<italic>r</italic> = 0.330, <italic>p</italic> = 0.011), but not for the inferior frontal gyrus, orbitofrontal cortex, anterior cingulate cortex, or anterior insular cortex.</p></sec><sec><title>Conclusion</title><p>This study could not confirm the suggested link between striatal D2/3R availability and subjective autonomous motivation to exercise among older adults. The exploratory findings, however, propose that frontal brain regions may be involved in the intrinsic regulation of exercise-related behaviors, though this has to be confirmed by future studies using a more suitable ligand and objective measures of physical activity levels.</p></sec>