Health Science Reviews

By Nosizwe Manyana

In this study, the relationship between substance misuse, brain structures and schizophrenia risk are explored. Schizophrenia is a complex mental health condition characterized by structural abnormalities that affects how people think feel, feel and behave. Ventricular enlargement and decreased prefrontal volume are consistent observations in people with schizophrenia. People who later become ill can frequently have these brain structural abnormalities identified before the disorder’s clinical starting point, suggesting that they represent a risk factor rather than just a side effect of medicine. Substance misuse is closely linked to brain structural abnormalities and schizophrenia, with alcohol, tobacco, and cannabis being the three most often abused substances.

To uncover how substance misuse influences brain development and schizophrenia risk, researchers followed young people with a genetic predisposition to the disorder. They collected MRI scans and substance use histories at the start, then tracked participants over several years to see who became ill. The focus was on how alcohol, cannabis, and tobacco affected brain structure especially the ventricles and frontal lobes and whether these changes predicted schizophrenia onset.

figure1 Bar Graph Illustrating Increased Volume of the Right Lateral Ventricle (SE)in Association with Increasing Levels of Exposure to Alcohol.

figure2 Bar Graph Illustrating Increased Volume of the Third Ventricle (SE)in Association with Increasing Levels of Exposure to Cannabis.

The study discovered a strong correlation between a history of heavy cannabis use or alcohol dependence and a higher chance of later developing schizophrenia. The study found that young people with a genetic risk for schizophrenia who used alcohol or cannabis showed early brain changes like enlarged ventricles and smaller frontal lobes linked to the disorder. Heavy use worsened these brain alterations, and regular cannabis use, and alcohol dependence were linked to an increased risk of schizophrenia. In other words, even modest substance use may hasten the onset of disease in brains that are already at risk.

Reference
Welch, K.A. et al. (2010) ‘The impact of substance use on brain structure in people at high risk of developing schizophrenia,’ Schizophrenia Bulletin, 37(5), pp. 1066–1076. https://doi.org/10.1093/schbul/sbq013.