Cannabis and Schizophrenia

It is always a point of contention in discussing substance abuse whether alcohol or marijuana is worse for you. Alcohol is worse for mood change, leading to more criminal behavior on an acute basis. Angry drunks. Alcohol is worse for balance, affecting navigation. Drunk driving. Marijuana is worse on just about every other count. Long-term studies have inherent chicken-and-egg weaknesses: does marijuana make people unmotivated, or do unmotivated people gravitate to marijuana? But increased paranoia, spatial response deterioration, isolation, abuse of other substances, longer periods of unemployment, psychiatric hospitalization, and anhedonia are all associated with cannabis use.

So when I have some summary evidence I like to pass it along. I excerpt from an article by Alan I. Green, MD, professor of psychiatry at Dartmouth Medical School:

While data indicate that first episode patients presenting with Cannabis Use Disorder (CUD) have an earlier onset of of illness and a poorer outcome than those without CUD, continued cannabis use after antipsychotic treatment, which occurs in approximately 50% of these patients in the initial months after hospitalization, is associated with an even worse outcome. The apparent “toxicity” of cannabis use in first episode patients is paralleled by data from chronic patients, in who CUD is associated with clinical exacerbations, non-compliance with treatment, poor global functioning, and increased relapse.

A growing body of data suggests that a critical period exists in patients with schizophrenia during the early phases of psychosis in which symptoms and and functioning continue to worsen, and that treatment with antipsychotic medications during this period may improve the natural course of the disorder.

Note to professionals: the occasion for the article is discussion of an ongoing study of clozapine versus first-generation antipsychotics in first-episode schizophrenia. Because of the receptors it targets, clozapine may make it easier to refrain from cannabis use during the critical period of those first few months, leading to better long-term outcomes.