Williams syndrome (WS) is a genetic condition characterized by a hypersocial personality and desire to form close relationships, juxtaposed with significant anxieties of nonsocial events. The neural underpinnings of anxiety in individuals with WS are currently unknown. Aberrations in the anatomical and microstructural integrity of the uncinate fasciculus (UF) have been recently implicated in social and generalized anxiety disorders. Based on these findings, we tested the hypothesis that the reported anxieties in individuals with WS share similar neuropathological correlates. Toward this end, diffusion tensor imaging (DTI) methods were employed to examine the microstructural integrity (fractional anisotropy, mean diffusivity, longitudinal diffusivity) of the UF in 18 WS and 15 typically developing adults (TD). Anxiety and sociability questionnaires were administered to determine associations with DTI indices of UF across groups. Results revealed comparable white matter integrity of the UF across groups, yet elevated subjective experience of anxiety in those with WS. Additionally, sociability and UF microstructural properties were dissociated across both groups. Whereas no relationships were found between DTI indices and anxiety in TD participants, strong negative associations were observed between these constructs in individuals with WS. Findings indicated that increased anxiety manifested by individuals with WS was associated with DTI measures of the UF and may signal structural or possibly physiological aberration involving this tract within the prefrontal-temporal network.
Keywords: Anxiety; DTI; Sociability; Uncinate fasciculus; Williams syndrome.