Testing dopaminergic markers of problematic social media use using neuromelanin-sensitive MRI

• NM-MRI offers a non-invasive measure of dopamine functioning in PSMU • No significant relationship was found between NM-MRI signal and PSMU • Dopamine should be examined in larger, more diverse samples with high PSMU levels • Findings highlight the need to uncover the neurobiological mechanisms of PSMU Neuromelanin-sensitive MRI (NM-MRI) has demonstrated potential as a proxy measure of dopamine functioning in the brain. Altered NM-MRI has been associated with substance use disorders, yet remains unexplored in problematic social media use (PSMU). The current study aims to determine whether higher PSMU is linked to lower NM-MRI signal intensity in the substantia nigra and ventral tegmental area (SN-VTA) Seventy-two young adults (18-35 years of age) completed the Bergen Social Media Addiction Scale to measure PSMU and underwent an NM-MRI scan. Half of the participants had a first degree relative (FDR) with a psychotic disorder. Within the SN-VTA, the average contrast-to-noise ratio was calculated on NM-MRI images. Linear regressions included NM-MRI signal intensity and PSMU scores, with FDR status, sex, and age as covariates. Higher levels of PSMU were not significantly associated with average NM-MRI signal intensity in the whole SN-VTA (p = 0.65). Voxelwise analysis revealed ninety-nine voxels with higher NM-signal intensity (p corrected > 0.05). No significant main effect or interactions were observed for any covariates. As the first application of NM-MRI to examine dopaminergic markers in relation to PSMU, these results highlight the importance of further studying brain correlates of PSMU beyond dopaminergic neuroadaptation.