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Gray matter loss increased in cannabis-using schizophrenia patients
By Andrew Czyzewski
03 April 2008
Am J Psychiatry 2008; 165: 490-496
MedWire News: reductions in gray matter volume than non-using patients and mentally healthy individuals, results of a longitudinal magnetic resonance imaging (MRI) study show.
The findings help to explain the well-known detrimental effects of cannabis use on schizophrenia symptoms, although the researchers concede that it is still unclear whether cannabis directly causes neuronal damage in these patients.
MRI studies in patients with schizophrenia have shown overall decreases in cortical gray and white matter volume, as well as increases in the lateral ventricles, which appear to progress with time and correlate with poor outcome, observe Monica Rais and colleagues from the University Medical Center Utrecht in The Netherlands.
Meanwhile, cannabis use has been consistently associated with poor clinical and functional outcome in schizophrenia patients, particularly with regard to positive symptoms, they add.
"If brain volume changes over time are most prominent in the patients with a poor outcome, and poor outcome is associated with cannabis use, one would expect cannabis use to be associated with excessive decreases in brain volumes," Rais and colleagues reason.
For the current study, the researchers recruited 51 patients with a recent first episode of schizophrenia and 31 mentally healthy controls.
MRI scans were performed on all individuals at inclusion to the study and at the 5-year follow-up. Nineteen patients used cannabis but no other illicit drugs during the study period while 32 patients did not use any drugs.
At inclusion, schizophrenia patients showed similar positive and negative symptom scores regardless of cannabis use. Patients also did not differ significantly on any of the brain volume measurements at inclusion.
After 5 years, cannabis-using schizophrenia patients displayed an average 2.67% decrease in gray matter volume relative to their non-using peers, and a 5.09% reduction relative to mentally healthy controls.
Concurrent with this observation, the researchers found a 10.99% increase in lateral and 14.89% increase in third ventricle volume in cannabis-using patients relative to their non-using peers.
Patients not using cannabis showed a small but significant improvement in positive and negative symptoms compared with the cannabis-using group over the follow-up period.
Discussing their findings in the American Journal of Psychiatry, Rais and colleagues say brain volume changes could be a direct consequence of cannabis intake or occur as a result of psychotic symptoms associated with cannabis use.
In support of the latter view, it has been suggested that brain changes in the early stages of schizophrenia are the result of the "toxic" effect of the psychotic state, the researchers add.
Abstract
By Andrew Czyzewski
03 April 2008
Am J Psychiatry 2008; 165: 490-496
MedWire News: reductions in gray matter volume than non-using patients and mentally healthy individuals, results of a longitudinal magnetic resonance imaging (MRI) study show.
The findings help to explain the well-known detrimental effects of cannabis use on schizophrenia symptoms, although the researchers concede that it is still unclear whether cannabis directly causes neuronal damage in these patients.
MRI studies in patients with schizophrenia have shown overall decreases in cortical gray and white matter volume, as well as increases in the lateral ventricles, which appear to progress with time and correlate with poor outcome, observe Monica Rais and colleagues from the University Medical Center Utrecht in The Netherlands.
Meanwhile, cannabis use has been consistently associated with poor clinical and functional outcome in schizophrenia patients, particularly with regard to positive symptoms, they add.
"If brain volume changes over time are most prominent in the patients with a poor outcome, and poor outcome is associated with cannabis use, one would expect cannabis use to be associated with excessive decreases in brain volumes," Rais and colleagues reason.
For the current study, the researchers recruited 51 patients with a recent first episode of schizophrenia and 31 mentally healthy controls.
MRI scans were performed on all individuals at inclusion to the study and at the 5-year follow-up. Nineteen patients used cannabis but no other illicit drugs during the study period while 32 patients did not use any drugs.
At inclusion, schizophrenia patients showed similar positive and negative symptom scores regardless of cannabis use. Patients also did not differ significantly on any of the brain volume measurements at inclusion.
After 5 years, cannabis-using schizophrenia patients displayed an average 2.67% decrease in gray matter volume relative to their non-using peers, and a 5.09% reduction relative to mentally healthy controls.
Concurrent with this observation, the researchers found a 10.99% increase in lateral and 14.89% increase in third ventricle volume in cannabis-using patients relative to their non-using peers.
Patients not using cannabis showed a small but significant improvement in positive and negative symptoms compared with the cannabis-using group over the follow-up period.
Discussing their findings in the American Journal of Psychiatry, Rais and colleagues say brain volume changes could be a direct consequence of cannabis intake or occur as a result of psychotic symptoms associated with cannabis use.
In support of the latter view, it has been suggested that brain changes in the early stages of schizophrenia are the result of the "toxic" effect of the psychotic state, the researchers add.
Abstract
