Effects of recreational cannabis use and subclinical psychosis risk on brain white matter integrity and structural connectivity in adolescence

Abstract

The impact of cannabis use on the psychosis risk in the healthy population has been less examined in the literature. Furthermore, previous diffusion tensor imag-ing and structural connectivity studies investigating the effects of cannabis use and psychosis risk offer contradictory results. To address these gaps and inconsistencies in the literature, the author examined whether recreational use of cannabis increases the risk of subclinical psychosis. The author further ex-amined the relationship between recreational cannabis use, subclinical psychosis, and white matter microstructure or structural network connectivity. Twenty-five adolescent cannabis users and 25 demographically matched controls participated in the study. The Cannabis Experience Questionnaire (CEQ) was used to assess cannabis consumption. Subclinical psychosis was evaluated with the Community Assessment of Psychic Experience (CAPE-42) questionnaire. While ROI-based Tract Based Spatial Statistics (TBSS) was used to examine white matter integrity in specified region of interests, Structural Connectivity Analysis was performed to examine brain structural topology. White matter integrity was assessed by four diffusion tensor derived measures: fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity, while structural network topology was examined by several graph-theory metrics: global efficiency, local efficiency and clustering coefficient. In order to eliminate possible confounding effects of alcohol and to-bacco use, weekly alcohol and daily tobacco consumption were also considered. The findings revealed that cannabis users scored higher on subclinical psychosis compared to non-users. ROI-based TBSS analysis indicated that cannabis use and subclinical psychosis do not affect white matter integrity in corpus collosum and superior longitudinal fasciculus. Similarly, the network connectivity parame-ters were not affected by the recreational cannabis use and psychosis risk. These results might indicate that recreational cannabis use increases the psychosis risk in adolescence, but that recreational cannabis use and subclinical psychosis risk together do not affect white matter microstructure and topology.