Dual Diagnosis Of Schizophrenia Research Articles

Cannabis use selectively modulates circulating biomarkers in the blood of schizophrenia patients.

Cannabis use disorder is frequent in schizophrenia patients, and it is associated with an earlier age of onset and poor schizophrenia prognosis. Serotonin 2A receptors (5‐HT2AR) have been involved in psychosis and, like Akt kinase, are known to be modulated by THC. Likewise, endocannabinoid system dysregulation has been suggested in schizophrenia. The presence of these molecules in blood makes them interesting targets, as they can be evaluated in patients by a minimally invasive technique. The aim of the present study was to evaluate 5‐HT2AR protein expression and the Akt functional status in platelet homogenates of subjects diagnosed with schizophrenia, cannabis use disorder, or both conditions, compared with age‐ and sex‐matched control subjects. Additionally, endocannabinoids and pro‐inflammatory interleukin‐6 (IL‐6) levels were also measured in the plasma of these subjects. Results showed that both platelet 5‐HT2AR and the active phospho (Ser473)Akt protein expression were significantly increased in schizophrenia subjects, whereas patients with a dual diagnosis of schizophrenia and cannabis use disorder did not show significant changes. Similarly, plasma concentrations of anandamide and other lipid mediators such as PEA and DEA, as well as the pro‐inflammatory IL‐6, were significantly increased in schizophrenia, but not in dual subjects. Results demonstrate that schizophrenia subjects show different circulating markers pattern depending on the associated diagnosis of cannabis use disorder, supporting the hypothesis that there could be different underlying mechanisms that may explain clinical differences among these groups. Moreover, they provide the first preliminary evidence of peripherally measurable molecules of interest for bigger prospective studies in these subpopulations.

Prevalence and covid 19 vaccination rate in a population of patients with schizophrenia and a substance use disorder

IntroductionAs of August 27th, 2021, the diagnosed cases of COVID 19 in Spain are 4 758 003 with a prevalence of 10.03%. 68.4% of the Spanish population is fully vaccinatedObjectivesPrimary: To compare the prevalence of COVID infection in a cohort of patients with schizophrenia to patients with a dual diagnosis of schizophrenia and substance use disorder Secondary: To compare the rate of fully vaccinated patients diagnosed with schizophrenia with and without a coexisting substance use disorder.MethodsRetrospective descriptive study. The population in study is made up of patients with schizophrenia (46) and dual diagnosis schizophrenia (28) (following DSM 5 criteria) Confirmed cases were those cases with positive PCRResultsThere was not a stadistically significant difference in the prevalence of COVID 19 infection between both groups of patients. The prevalence of COVID infection among the dual diagnosis schizophrenia was 3.57% compared to 6.5% in those without coexisting substance abuse disorder. Relative to vaccination rate, we didn’t find a stadistically significant difference between both groups. However, there was a higher vaccination rate in the dual diagnosis schizophrenia group (82.12%) compared to the non-dual diagnosis schizophrenia group (69.56%)ConclusionsThe prevalence of COVID 19 infection in the dual diagnosis schizophrenia cohort is 3.57% and in the group of patients with schizophrenia without substance abuse disorder is 6,5%. In those with dual diagnosis schizophrenia the vaccination rate was un 82.12%. It was 69.56% in those without coexisting substance abuse disorder.DisclosureNo significant relationships.

Alcohol and Psychosis: A Narrative Review of the Prevalence, Clinical Manifestations, and Management of Alcohol-related Psychotic Symptoms

Background: Alcohol use disorders, defined as the maintenance of alcohol use for at least a 12-month period despite negative psychological, biological, behavioral, and social consequences, are frequently associated with psychotic symptoms. Objective: Our aim in this paper is to review alcohol-related clinical conditions that are accompanied by psychotic symptoms, alcohol-induced psychotic disorder, alcohol withdrawal delirium, Wernicke’s encephalopathy, Korsakoff’s dementia, comorbid schizophrenia, or delusional disorder. Methods: This is a non-systematic, narrative review based on the relevant literature indexed in PubMed and Google Scholar databases [2000-2020]. Results: Alcohol-induced psychotic disorder is characterized by the presence of auditory hallucinations or delusions. In the state of alcohol withdrawal, tactile, visual hallucinations and delusions are common. Wernicke-Korsakoff syndrome, caused by malnutrition secondary to chronic alcohol misuse, is characterized by the presence of ataxia, ophthalmoplegia, and a range of mental disturbances. The dual diagnosis of schizophrenia and alcohol use disorder rests on shared biological impairments, as shown by neuroendocrinological and brain imaging studies. The subtype of the delusional disorder called Othello’s syndrome, or delusional jealousy based on false beliefs of infidelity, is often seen in the context of alcohol alone or alcohol and neurological disorder. Treatment for alcoholic disorders with psychotic symptoms are dietary, psychological, and pharmacological. Conclusions: There are a number of alcohol-related psychotic syndromes, each requiring its own specific treatment approach.

Aripiprazole reduces liver cell division.

Effects of aripiprazole on dopamine regulation are being tested as a treatment for patients with a dual diagnosis of schizophrenia and addictions, often cocaine dependence. Aripiprazole has one of the fewest side-effects among the second-generation antipsychotics. Nevertheless, severe aripiprazole hepatotoxicity was reported in persons with a history of cocaine and alcohol abuse. Here we report that therapeutically relevant aripiprazole concentrations, equal to laboratory alert levels in patients' serum, reduce the rate of hepatocytes' division. This could be an underlying mechanism of severe liver injury development in the patients with a history of alcohol and cocaine abuse, the two hepatotoxic agents that require increased ability of liver self-regeneration. Monitoring liver functions is, therefore, important in the cases when aripiprazole is co-prescribed or used with drugs with potential hepatotoxic effects.

Long-Term Ethanol Alcoholization Decreases Levodopa- Induced Aggressive Behavior in Rats

One of the old but still unsolved problems in psychiatry is the treatment of patients with a dual diagnosis of schizophrenia and alcoholism. Numerous clinical studies failed to explain unambiguously the mechanisms of formation of these comorbid disorders. Experimental modeling of dual disorders was carried out using a model of schizophrenia based on the impaired development and dopamine hypothesis of schizophrenia. To model comorbid experimental schizophrenia and alcohol abuse, the dopamine precursors, Levodopa/Carbidopa (LC), were used in combination with 15% ethanol. The aim of this study was to investigate social behavior of rats receiving LC and exposed to intermittent semi-compulsory alcoholization. After three months of the experiment, there were significantly more interactions (including aggressive–attacks, fights, bites) and submissive postures in the group of rats that received LC. Combined LC/ethanol administration did not alter rat social behavior in contrast to ethanol administered alone.

Symptômes négatifs dans la schizophrénie et addiction

Dual diagnosis of schizophrenia and substance-related disorders is common in psychiatric practice. Epidemiologic studies and report have established that the risk of a substance-related disorder was 4 to 5 times higher in a population of psychiatric patients than in the general population. However, little is known on the reason of this relationship and the treatments required. It's well known that a family history of psychosis is a risk factor of schizophrenia. Similarly a family history of substance use disorders increases the risk of using substances. Because the two disorders often occurred together, it could be hypothesized that a genetic risk factor is common. However, recent studies did not confirm this hypothesis and it seems that their genetic risks factor would be unrelated. Evidence now exists describing the different profiles of patients whether they used substance or not. Concerning negative symptoms clinical studies and meta-analyses have described fewer symptoms in schizophrenia patients with a substance use disorder. Among the different explanations that have been addressed, it seems that a lower capability of obtaining the substance could partly explain this relationship. Perhaps because patients with social withdrawal have more difficulties to find and spend the time required to obtain abused substances. At the opposite some products such as cocaine may relieve some symptoms especially anhedonia and alogia. However the link between substance-related disorders and negative symptoms is weak and decreases in more recent studies, probably because negative symptoms as well as addiction disorders are better characterized. Considering that treating psychiatric symptoms may not always lead to a decrease in the substance-related disorders but that patients who give up substances improve their psychotic symptoms, a therapeutic strategy should be planned for these dual disorders patients combining psychiatry and addiction interventions.

Tobacco smoking in persons with schizophrenia followed up at a teaching hospital in Sri Lanka

Background Studies in Western populations indicate that the prevalence of smoking in patients with schizophrenia ranges from 70-90%. Data from low and middle income countries is sparse. Aims To determine the prevalence of smoking in patients with schizophrenia, and to identify probable associations. Methodology The study was conducted at the psychiatry outpatient clinics of Colombo North Teaching Hospital, Ragama. Consecutive outpatients who met ICD-10 diagnostic criteria for schizophrenia were invited to answer an interviewer administered, pre-tested questionnaire on socio-demographic status, smoking habits, disease and treatment related characteristics. The Fagerstrom’s Test for Nicotine Dependence was used to grade the level of nicotine addiction. Results Of the 400 patients with schizophrenia, 171 (42.8%) were smokers. Of them 150 (87.7%) were dependent on nicotine. In terms of Fagerstrom’s Test, high dependence was seen in 3.3% ( n =5) while 39.2% ( n =59) and 57.3% ( n =86) reported moderate and low dependence respectively. All the smokers were male. For a majority of the patients the age of initiation of smoking was between 16-25 years, correlating with the onset of schizophrenia. Interestingly, most of the smokers (63.2%) were keen to quit smoking. Participants who smoked were significantly more likely to misuse other substances ( p =0.001) and to suffer from physical illnesses ( p =0.0001), compared to non-smokers. Smokers were also significantly more likely to be on intramuscular depot antipsychotics ( p =0.032), whereas non-smokers in contrast, were more likely to be on atypical antipsychotics ( p =0.0001). Conclusion A dual diagnosis of schizophrenia and nicotine dependence could be made in nearly half of our study population with schizophrenia. Although these rates are lower than in western populations, it is an issue that needs to be addressed in the treatment. DOI: http://dx.doi.org/10.4038/sljpsyc.v5i2.7816 Sri Lanka Journal of Psychiatry Vol 5(2):19-23

Cognitive Behavioral Therapy (CBT) and Meditation Awareness Training (MAT) for the Treatment of Co-occurring Schizophrenia and Pathological Gambling: A Case Study

There is a paucity of interventional approaches that are sensitive to the complex needs of individuals with co-occurring schizophrenia and pathological gambling. Utilizing a single-participant design, this study conducted the first clinical evaluation of a novel and integrated non-pharmacological treatment for a participant with dual-diagnosis schizophrenia and pathological gambling. The participant underwent a 20-week treatment course comprising: (i) an initial phase of second-wave cognitive behavioral therapy (CBT), and (ii) a subsequent phase employing a meditation-based recovery model (involving the administering of an intervention known as Meditation Awareness Training). The primary outcome was diagnostic change (based on DSM-IV-TR criteria) for schizophrenia and pathological gambling. Secondary outcomes were: (i) psychiatric symptom severity, (ii) pathological gambling symptom severity, (iii) psychosocial functioning, and (iv) dispositional mindfulness. Findings demonstrated that the participant was successfully treated for both schizophrenia and pathological gambling. Significant improvements were also observed across all other outcome variables and positive outcomes were maintained at 3-month follow-up. An initial phase of CBT to improve social coping skills and environmental mastery, followed by a phase of meditation-based therapy to increase perceptual distance from mental urges and intrusive thoughts, may be a diagnostically-syntonic treatment for co-occurring schizophrenia and pathological gambling.

Comorbid substance use disorder in schizophrenia: A selective overview of neurobiological and cognitive underpinnings

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.

791 – Dual diagnosis of schizophrenia and substance abuse: the need for awareness

Background The dual diagnosis of substance abuse and severe mental illness has been proposed by some authors to highlight the high frequency of such association. Our objectif was to determine the prevalence of dual diagnosis among mentally ill patients and and particularly schizophrenic patients. As a secondary purpose, to describe the profile of patient at higher risk to develop dual diagnosis. Method 683 mentally ill patients were recruited from el Mamoura Psychiatric Hospital, they were assessed by the Arabic version of 6 item K6 scale, those scoring above 13 were submitted to a structured clininical interview SCID-I module for schizophrenia, urine screening for drugs of abuse and complete history of substance abuse and other medical disciplines. Results 22% of the sample fulfill the diagnosis of dual diagnosis. 28.99% of the sample were schizophrenic, 16.67% among the later were fulfilling diagnosis of dual diagnosis. Results reveals higher risk for dual diagnosis in patients younger in age, single, low socioeconomic state and low level of education. Those having dual diagnosis tend to have early onset, longer duration of illness, poor compliance, higher rate of smoking and increased number of relapses. Conclusion Double diagnosis is an important issue that needs more focus in mental health services. Awareness of mental health providers about dual diagnosis is highly recommended.

Markedly elevated plasma levels of interleukin-1 receptor antagonist in patients with dual diagnosis of schizophrenia and substance use disorders

Markedly elevated plasma levels of interleukin-1 receptor antagonist in patients with dual diagnosis of schizophrenia and substance use disorders

P03-198 - Functional performance in activities of daily living of individuals with a dual-diagnosis of schizophrenia and substance-use disorder

IntroductionResearch on functional performance of individuals with schizophrenia and substance use is limited, focusing primarily on cognitive impairments. Research findings are conflicting, making it difficult to understand how these individuals function despite their cognitive impairments. There is a need to use performance-based assessments to understand how individuals with a dual-diagnosis accomplish their daily living activities.AimsTo describe the functional performance of individuals with a dual-diagnosis in two activities of daily living, using a performance-based assessment.ObjectivesTo compare the functional performance of individuals with a dual-diagnosis, in grocery shopping and budgeting.MethodsThis descriptive cross-sectional study included ten participants with a dual-diagnosis of schizophrenia and substance-use disorder, aged 21 to 35, living independently in the community. They were evaluated on two tasks, budgeting and grocery shopping, using the Perceive-Recall-Plan-Perform (PRPP) system of task analysis (Chapparo & Ranka, 2005). The PRPP is a standardized criterion-referenced task-based assessment, and is valuable in describing individuals’ community functioning with regards to information-processing difficulties. Substance use was evaluated with the Addiction Severity Index (McLellan et al., 1989).ResultsPreliminary results indicate lower scores on both tasks, in the planning quadrant of the PRPP, particularly the evaluating sub-quadrant, which involves cognitive monitoring and appraisal processes. This trend occurs despite the participant's prior familiarity with tasks. Conclusions: This study is a first step in describing the functional performance of individuals with a dual diagnosis of schizophrenia and substance use in activities of daily living. This information will lead to improved rehabilitation for these clients.

Cognitive impairment in dual diagnosis inpatients with schizophrenia and alcohol use disorder

Cognitive impairment has been found independently among individuals with schizophrenia and individuals with alcohol use disorders. Less is known about the nature and severity of cognitive impairment in patients with a dual diagnosis, though the co-occurrence of these disorders may further exacerbate cognitive impairment. The study investigates the possible additive effect of alcohol use disorder and schizophrenia on cognitive impairment among patients diagnosed with schizophrenia. Participants were inpatients with schizophrenia ( n = 30), inpatients with a dual diagnosis of schizophrenia and alcohol use disorder ( n = 30), and matched controls ( n = 30): all completed a comprehensive neuropsychological battery. Both patient groups were significantly impaired, relative to controls, across the battery. Dual diagnosis patients were significantly more impaired than schizophrenia patients on delayed verbal memory, and executive functioning, primarily set-shifting, working memory, and planning, and had higher psychiatric morbidity scores. The findings provide support for an additive effect of the two disorders on cognitive impairment. These cognitive deficits may affect capacity to engage in treatment, increase risk of relapse, and adversely affect treatment outcomes. An understanding of the cognitive profile of people with dual diagnosis may help to tailor treatment delivery to meet their specific needs, enhance cognitive strengths, accommodate deficits and improve treatment outcomes.

Influence of Family Involvement and Substance Use on Sustained Utilization of Services for Schizophrenia

This observational study assessed the influence of family support and substance abuse on patterns of service use by individuals with schizophrenia. Polychotomous logistic regression was used to analyze an existing database for 258 individuals with schizophrenia who were between the ages of 18 and 67 and were recruited from public mental health care settings. Analyses determined the extent to which two consumer-identified factors, family support and substance abuse status, influenced patterns of outpatient service use (regular, irregular, and infrequent) for schizophrenia. After the analysis adjusted for insight into illness, cognitive functioning, rural or urban residence, and gender, comorbid substance abuse and the interaction between substance abuse status and family support were significantly associated with patterns of service use. Comorbid substance abuse predicted irregular or infrequent patterns of service use over time. Stratified analyses indicated that weekly family support substantially reduced the adverse impact of substance abuse status on consumers' patterns of service use, especially for those living in rural areas. This study provides evidence that ongoing family support is associated with substantial reductions in the adverse impact of substance abuse on consumers' patterns of service use, especially for consumers living in rural areas. If confirmed in other populations, study findings suggest that reinforcing services and support for family members who provide informal care helps to sustain involvement in care by the especially vulnerable population of individuals with a dual diagnosis of schizophrenia and substance abuse.

Working memory and depressive symptoms in patients with schizophrenia and substance use disorders

Background. 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. Objective. 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. Methods. 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). Results. Patients in the dual diagnosis group displayed more severe depressive symptoms and poorer strategy during the working memory task. Conclusions. 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.

Meta-Analysis of Depressive Symptoms in Dual-Diagnosis Schizophrenia

Substance abuse is highly prevalent in schizophrenia and associated with numerous negative consequences. While studies have regularly reported more severe depressive symptoms in addicted schizophrenia patients relative to non-abusing patients, some studies have not corroborated this finding. The current meta-analysis was performed to quantify the relative severity of depressive symptoms in dual-diagnosis schizophrenia. A search of the literature using computerized engines was undertaken. Studies were retained in the analysis if (i) they assessed depressive symptoms using validated scales specific to depression (e.g. Hamilton Depression Rating Scale); and (ii) groups of schizophrenia patients were divided according to substance use disorders (alcohol, amphetamines, cannabis, cocaine, hallucinogens, heroin and/or phencyclidine). According to the inclusion criteria, 20 studies were available for mathematical analysis. A small, positive and significant effect size estimate (n =3283; 1680 dual diagnosis; 1603 single diagnosis; adjusted Hedges's g =0.292; p =0.003) was obtained, within a random-effect model, suggesting that some dual-diagnosis patients experience more severe depressive symptoms than single-diagnosis patients. This significant difference was found only for studies using the Hamilton Depression Rating Scale but not for other depression scales. The results of the present meta-analysis suggest that addicted schizophrenia patients experience more severe depressive symptoms compared to non-abusing patients, but that the difference is smaller than commonly assumed. The meta-analysis also shows that the significance of results is related to the scale used to measure depressive symptoms. These results have methodological implications for future studies of depressive symptoms in dual-diagnosis patients, and potential implications for the prevention and treatment of depressive symptoms in schizophrenia.

Processing of social emotion in patients with schizophrenia and substance use disorder: An fMRI study

The lifetime prevalence of substance use disorders among schizophrenia patients is close to 50%. The negative consequences of substance abuse in schizophrenia are well documented, but the aetiology of this comorbid condition remains unknown. Mounting evidence suggests that dual-diagnosis patients have fewer negative symptoms and better social skills, compared to non-abusing patients. We hypothesized that schizophrenia patients with substance use disorder (SCZ–SUD) would display increased cerebral activations in response to socioemotional stimuli, relative to patients with no SUD (SCZ). Schizophrenia patients (DSM-IV criteria) were divided into two groups: patients with (n=12) and without (n=11) substance use (alcohol and/or cannabis). Using functional magnetic resonance imaging (fMRI), patients were scanned during passive viewing of an emotional film excerpt with social content. Loci of activation were identified in the right mPFC (BA 10) and the right supramarginal gyrus (BA 40) in SCZ–SUD patients, and in the left pons in SCZ patients. Relative to SCZ patients, increased loci of activation were found in the right superior parietal cortex (BA 7) and the left medial prefrontal cortex (BA 10) in SCZ–SUD patients, who reported higher subjective emotional experience on a self-report scale. To our knowledge, this is the first fMRI study to assess social emotions in dual-diagnosis schizophrenia. Our results suggest that socioemotional processing may be less impaired in dual diagnosis, which recruited brain regions seemingly involved in “social cognition.” Further studies on the topic are warranted.

Screening for cognitive functioning in psychiatric outpatients with schizophrenia, alcohol dependence, and dual diagnosis

Cognitive impairment is common to both schizophrenia and alcoholism. Despite increasing recognition that people with both disorders represent a problematic client group, little is known about the possible additive effect of a dual diagnosis upon impaired cognitive function. This study investigates impairment of cognitive functioning in patients with schizophrenia, alcohol dependence, or a dual diagnosis of schizophrenia and alcohol use disorder. It was hypothesised that patients with dual diagnosis would show greater cognitive impairment than those with a single diagnosis. The Mini-Mental State Examination (MMSE) and standardised measures of psychiatric health and substance use were administered to 120 community psychiatric patients with a diagnosis of schizophrenia, alcohol dependence and both conditions (dual diagnosis). Higher rates of cognitive impairment were found among dual diagnosis patients compared to the schizophrenia or alcohol patients. This was shown in age-adjusted measures of global functioning, and on the tests of language, reading and writing, and visuospatial construction. Despite its common usage, global MMSE scores were insensitive to the cognitive impairments typically found in these clinical groups. Where the MMSE is used as a screening tool, it is recommended that scores are adjusted for the effects of age.

Neural Correlates of the Affect Regulation Model in Schizophrenia Patients With Substance Use History

The lifetime prevalence of substance use disorders among schizophrenia patients is close to 50%. The negative consequences of substance abuse in schizophrenia are well documented, but the etiology of this comorbid condition remains unknown. According to the affect regulation model, schizophrenia patients abuse drugs in order to cope with their negative affects. Supporting the model, clinical studies have shown that dual-diagnosis patients have less blunting of affect and that they experience more negative affect. We hypothesized that patients with a history of substance use would have increased cerebral activations in response to aversive stimuli when compared to abstinent patients. Schizophrenia patients were divided into 2 groups: patients with (SCZ-SU group; N = 12) and without (SCZ group; N = 11) a current or past substance use disorder (alcohol, cannabis, and/or LSD). Diagnoses were made according to DSM-IV criteria. Using functional magnetic resonance imaging (fMRI), patients were scanned during passive viewing of emotionally negative pictures (International Affective Picture System). Data were gathered from September 2001 to December 2003. Subjectively, the emotional experience induced by viewing the negative pictures was rated significantly higher in the SCZ-SU group than in the SCZ group (p = .008). Neurally, in the SCZ-SU group, significant loci of activation were identified in the right medial prefrontal cortex (Brodmann's area [BA] 10), left medial prefrontal cortex (BA 10), right orbitofrontal cortex (BA 47), and left amygdala. No significant loci of activation were observed in the SCZ group. These results suggest that the functioning of the medial prefrontal cortex, thought to be impaired in patients with prominent negative symptoms, is more preserved in dual-diagnosis schizophrenia. This relative preservation could be primary or secondary to substance use.

A meta-analysis of negative symptoms in dual diagnosis schizophrenia

According to the self-medication hypothesis, schizophrenia patients would abuse psychoactive substances to get a relief from their negative symptoms. Studies testing the self-medication hypothesis in dual diagnosis (DD) schizophrenia have not been conclusive, with some studies showing that DD patients experience fewer negative symptoms, whereas other studies have failed to detect such differences. One potential confounding factor for this discrepancy lies in the diverse scales used to evaluate the negative symptoms. A systematic quantitative review of the literature using computerized search engines has been undertaken. Studies were retained in the analysis if: (i) they assessed negative symptoms using the SANS; (ii) groups of schizophrenia patients were divided according to substance use disorders (alcohol, amphetamines, cannabis, cocaine, hallucinogens, heroin and phencyclidine). Attainable published studies were screened. According to our inclusion criteria, 18 possible studies emerged. Data from 11 studies were available for mathematical analysis. A moderate effect size (total n = 1135, 451 DD, 684 single diagnosis, adjusted Hedges' g = -0.470, p = 0.00001) was obtained, within a random-effect model, suggesting that DD patients experience fewer negative symptoms. Groups did not differ in age, sex, and positive/general psychopathology. Using narrow criteria (e.g. SANS), the results of this meta-analysis show that schizophrenia patients with a substance use disorder experience fewer negative symptoms than abstinent schizophrenia patients. As such, these results suggest either that substance abuse relieves the negative symptoms of schizophrenia or that the patients with fewer negative symptoms would be more prone to substance use disorders.