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22-07-2009 | Mental health | Article

Additive cognitive impairment with schizophrenia and alcohol abuse


Free abstract

MedWire News: Schizophrenia and alcohol use disorder seem to have an additive effect on cognitive impairment, increasing the risk for relapse and adversely affecting treatment outcomes, conclude UK researchers.

Cognitive impairment is associated both with schizophrenia patients and individuals with alcohol use disorders. However, the occurrence and severity of cognitive impairment in patients with co-occurring schizophrenia and alcohol use disorder is not clear.

To investigate further, Victoria Manning, from the Institute of Psychiatry in London, and colleagues administered a comprehensive neuropsychological battery to 30 schizophrenia patients, 30 patients with a dual diagnosis of schizophrenia and alcohol use disorder, and 30 mentally healthy controls.

The three groups did not differ significantly in terms of sociodemographic characteristics. There were also no significant differences in the age of onset of alcohol use and the age of regular drinking, although dual diagnosis patients consumed significantly larger quantities of alcohol on each drinking occasion and had consumed alcohol on significantly more days in the past month than other patients.

The results, published in the journal Schizophrenia Research, reveal that schizophrenia patients performed significantly worse than controls on all tested neuropsychological domains except for verbal recognition, while dual diagnosis patients performed significantly worse than controls on all domains.

Further analysis indicated that dual diagnosis patients performed significantly worse than schizophrenia patients on delayed verbal memory, working memory, set-shifting (cognitive flexibility), and planning ability, at Z scores relative to controls of -2.21 versus -1.55, -1.50 versus -0.76, -2.50 versus -1.18, and -1.41 versus -0.66.

Overall, dual diagnosis patients had significantly worse memory and executive functioning scores. Logistic regression analysis demonstrated that dual diagnosis patients had significantly more impaired executive functioning, and worse psychiatric symptoms.

“The study supports the hypothesis that alcohol use disorders are associated with greater cognitive impairment among schizophrenia patients,” the team writes.

“Some of the patients with the greatest clinical need may profit the least from treatment, leading to poorer outcome and a likely reappearance in treatment.”

MedWire ( is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009

By Liam Davenport

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