Working memory and depressive symptoms in patients with schizophrenia and substance use disorders.
ABSTRACT Substance abuse is highly prevalent in schizophrenia and it has been associated with negative consequences on the course of the pathology. Regarding cognition, the prevailing literature has produced mixed results. Some groups have reported greater cognitive impairments in dual diagnosis schizophrenia, while other groups have described the reverse.
The current cross-sectional study sought to investigate the potential differences in psychiatric symptoms and cognition between schizophrenia patients with and without substance use disorders.
Fifty-three schizophrenia patients were divided into two groups: with (n=30) and without (n=23) a substance use disorder (DSM-IV criteria). Psychiatric symptoms were measured with the Positive and Negative Syndrome Scale (PANSS) and the Calgary Depression Scale for Schizophrenia (CDSS). Psychomotor speed and spatial working memory were measured using Cambridge Neuropsychological Tests Automated Battery (CANTAB).
Patients in the dual diagnosis group displayed more severe depressive symptoms and poorer strategy during the working memory task.
These results are in keeping with the prevailing literature describing negative consequences of substance abuse in schizophrenia. Substance abuse may exacerbate depressive symptoms and interfere with metacognition in schizophrenia.
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ABSTRACT: Although individuals with schizophrenia show a lifetime prevalence of 50% for suffering from a comorbid substance use disorder, substance abuse usually represents an exclusion criterion for studies on schizophrenia. This implies that surprisingly little is known about a large group of patients who are particularly difficult to treat. The aim of the present work is to provide a brief and non-exhaustive overview of the current knowledgebase about neurobiological and cognitive underpinnings for dual diagnosis schizophrenia patients. Studies published within the last 20 years were considered using computerized search engines. The focus was on nicotine, caffeine, alcohol, cannabis and cocaine being among the most common substances of abuse. All drugs of abuse target dopaminergic, glutamatergic and GABAergic transmission which are also involved in the pathophysiology of schizophrenia. Current literature suggests that neurocognitive function might beless disrupted in substance-abusing compared to non-abusing schizophrenia patients, but in particular the neuroimaging database on this topic is sparse. Detrimental effects on brain structure and function were shown for patients for whom alcohol is the main substance of abuse. It is as yet unclear whether this finding might be an artifact of age differences of patient subgroups with different substance abuse patterns. More research is warranted on the specific neurocognitive underpinnings of schizophrenia patients abusing distinct psychoactive substances. Treatment programs might either benefit from preserved cognitive function as a resource or specifically target cognitive impairment in different subgroups of addicted schizophrenia patients.Psychiatry and Clinical Neurosciences 07/2013; 67(6). DOI:10.1111/pcn.12072 · 1.62 Impact Factor
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ABSTRACT: Schizophrenia is a life-long debilitating mental disorder affecting tens of millions of people worldwide. The serendipitous discovery of antipsychotics focused pharmaceutical research on developing a better antipsychotic. Our understanding of the disorder has advanced however, with the knowledge that cognitive enhancers are required for patients in order to improve their everyday lives. While antipsychotics treat psychosis, they do not enhance cognition and hence are not antischizophrenics. Developing pro-cognitive therapeutics has been extremely difficult, however, especially when no approved treatment exists. In lieu of stumbling on an efficacious treatment, developing targeted compounds can be facilitated by understanding the neural mechanisms underlying altered cognitive functioning in patients. Equally importantly, these cognitive domains will need to be measured similarly in animals and humans so that novel targets can be tested prior to conducting expensive clinical trials. To date, the limited similarity of testing across species has resulted in a translational bottleneck. In this review, we emphasize that schizophrenia is a disorder characterized by abnormal cognitive behavior. Quantifying these abnormalities using tasks having cross-species validity would enable the quantification of comparable processes in rodents. This approach would increase the likelihood that the neural substrates underlying relevant behaviors will be conserved across species. Hence, we detail cross-species tasks which can be used to test the effects of manipulations relevant to schizophrenia and putative therapeutics. Such tasks offer the hope of providing a bridge between non-clinical and clinical testing that will eventually lead to treatments developed specifically for patients with deficient cognition. © The Author(s) 2014.Journal of Psychopharmacology 12/2014; 29(2). DOI:10.1177/0269881114555252 · 2.81 Impact Factor
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ABSTRACT: Objective: Individuals with either schizophrenia or a substance use disorder have been shown to independently display cognitive deficits. Patients with schizophrenia who abuse psychoactive substances should then arguably display an aggravation in cognitive impairment. However, cognitive integrity among individuals with dual diagnosis remains paradoxical with some studies reporting dysfunction, and others reporting preservation. Methods: A literature search of PubMed and PsycInfo was conducted using the following major inclusion criteria: (1) schizophrenia-spectrum disorder; (2) presence or absence of a substance use disorder; (3) measures of cognitive function. Results: Young patients with schizophrenia and comorbid substance abuse typically display better cognitive abilities than older individuals with dual diagnosis. Also, depending on the type of task assessed, cognition either remains relatively intact (e.g., psychomotor speed), dysfunctional (e.g., verbal memory) or ambiguous (e.g., impulsivity). Performance on tasks of impulsivity, however, remains particularly difficult to interpret, most probably due to the complexity of the multidimensional construct of this cognitive domain. Finally, depending on the preference of psychoactive substance used, some individuals with dual diagnosis exhibit better cognitive function (e.g., cannabis), while others display marked decreases on task performance (e.g., alcohol), relative to those with schizophrenia-only. Conclusions: Age, type of cognitive function measured and type of psychoactive substance abused appear to be three factors that interact to contribute to the array of current findings among patients with dual diagnoses of schizophrenia and substance use disorder.Journal of Dual Diagnosis 01/2012; DOI:10.1080/15504263.2012.648549 · 0.80 Impact Factor