The specific neuroanatomical features of nyaope addiction and associated co-morbid psychiatric disorders

Abstract

Nyaope is the street name for what is believed to be a drug cocktail in South Africa although recent research suggests that it is predominantly heroin. Nyaope powder is most commonly smoked together with cannabis, a drug-use pattern unique to the region. Due to the increasing burden of this drug in low-income communities and the absence of human structural neuroimaging of combination heroin and cannabis use disorder, we initiated the first ever cohort study in order to identify the neuroanatomical features of the disorder. We also sought to characterize the neuroanatomical sequalae of various clinical features. Twenty-eight male nyaope users and thirty healthy, matched controls were recruited from drug rehabilitation centers and the community, respectively. T1-weighted MRI images were obtained using a 3 Tesla General Electric Discovery and cortical and subcortical volumetric properties were examined and compared. Nyaope users displayed extensive grey matter atrophy in the right hemispheric medial orbitofrontal, rostral middle frontal, superior temporal, superior frontal, and supramarginal gyri (two-sided t-test, p < 0.05, corrected for multiple comparisons). No significant cortical or subcortical effects were found in clinical features such as relapse rate or current depressive episode. Our findings suggest cortical abnormality in nyaope users in regions involved in impulse control, decision making, social- and self-perception, and working memory. Importantly, affected brain regions show large overlap with the pattern of cortical abnormalities shown in heroin use disorder. Our findings suggest that treatment should include opioid agonist maintenance therapy according to the World Health Organization (WHO) guidelines