New Study: Marijuana Causes Psychosis

February 08, 2011 CNN

Psychopharmacology (Berl). 2012 Mar 9. [Epub ahead of print]

Delayed preattentional functioning in early psychosis patients with cannabis use.

Source

School of Psychology, University of Wollongong, Wollongong, NSW, 2522, Australia, nicole.pesa@sydney.edu.au.

Abstract

RATIONALE:

Cannabis use is prevalent among the early psychosis (EP) population. The event-related potentials, mismatch negativity (MMN) and P3a are reduced in EP. Cannabinoids have been shown to modulate N-methyl-D-aspartate receptors which are involved in MMN generation.

OBJECTIVES:

This study is the first to investigate the effects of cannabis use on MMN/P3a in EP.

METHODS:

EP was defined as a history of psychosis or psychotic symptoms with no progression to date to chronic schizophrenia. Twenty-two EP patients with cannabis use (EP + CANN), 22 non-cannabis-using EP patients (EP-CANN) and 21 healthy controls participated in this study. MMN/P3a was elicited using a two-tone, auditory paradigm with 8% duration deviants.

RESULTS:

As expected, EP-CANN showed marked reductions in MMN/P3a amplitudes compared to controls. However, EP + CANN showed evidence of a different pattern of neurophysiological expression of MMN/P3a compared to non-using patients, most notably in terms of delayed frontal MMN/P3a latencies.

CONCLUSIONS:

This study provides further evidence that MMN/P3a deficits are present during early psychosis and suggests that this biomarker may have utility in differentiating substance- from non-substance-related psychoses.

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