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18-08-2011 | Mental health | Article

Gray matter loss due to substance use ‘not increased in ARMS patients’


Free abstract

MedWire News: Individuals in an at-risk mental state (ARMS) for psychosis do not show greater levels of gray matter loss associated with substance use than mentally healthy individuals, show UK study results.

ARMS patients "have reduced gray matter compared to healthy volunteers, and, with transition to psychosis, show a further reduction in gray matter volume," write James Stone (King's College London) and team in the journal European Neuropsychopharmacology.

They add: "The cause of these changes is not known, but it has been suggested that reductions in gray matter volume might occur, in part, because of increased sensitivity in ARMS subjects to the potentially toxic effects of drugs and alcohol."

To investigate further, the team studied the relationship between gray matter volume and substance use in 27 ARMS patients and 27 age- and gender-matched mentally healthy controls.

All of the participants were interviewed about their past and current use of alcohol, cannabis, and nicotine, and underwent volumetric magnetic resonance imaging (MRI) scans of the brain.

There were no significant differences between the two groups in the use of alcohol, cannabis, or other illegal substances, but ARMS patients smoked more cigarettes per day, the researchers note.

Multivariate analysis, which also accounted for antidepressant or antipsychotic medication use, revealed that alcohol intake was negatively correlated with gray matter volume in the cerebellum, and cannabis intake was negatively correlated with gray matter volume in the prefrontal cortex.

Furthermore, number of cigarettes smoked was negatively correlated with gray matter in the left temporal cortex, parietal cortex, and occipital cortex.

These relationships were present in both ARMS patients and controls, with no significant differences between the groups in the extent of gray matter loss associated with substance use.

Stone and team conclude: "Alcohol, tobacco, and cannabis at low to moderate intake may be associated with lower gray matter in both ARMS subjects and healthy volunteers possibly representing low-level cortical damage or change in neural plasticity."

They add: "The present study does not support the hypothesis that ARMS subjects are at greater risk of gray matter changes associated with substance intake, although it is possible that at higher levels of intake, or with prolonged use, a differential effect may emerge."

By Mark Cowen

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