Treatment of substance use disorders in schizophrenia: a unifying neurobiological mechanism?

Randomized Laboratory Study of Single-Dose Cannabis, Dronabinol, and Placebo in Patients With Schizophrenia and Cannabis Use Disorder

BACKGROUND AND HYPOTHESIS

Up to 43% of people with schizophrenia have a lifetime cannabis use disorder (CUD). Tetrahydrocannabinol (THC) has been shown to exacerbate psychosis in a dose-dependent manner, but little research has assessed its effects on schizophrenia and co-occurring CUD (SCZ-CUD). In this double-dummy, placebo-controlled trial (total n = 130), we hypothesized that a modest dose of THC would worsen cognitive function but not psychosis.

STUDY DESIGN

Effects of single-dose oral THC (15 mg dronabinol) or smoked 3.5% THC cigarettes vs placebo in SCZ-CUD or CUD-only on positive and negative symptoms of schizophrenia (only for SCZ-CUD), cognition, and drug experiences assessed several hours after drug administration. SCZ-only and healthy control participants were also assessed.

STUDY RESULTS

Drug liking was higher in THC groups vs placebo. Neither smoked THC nor oral dronabinol predicted positive or negative symptom subscale scores 2 and 5 h, respectively, after drug exposure in SCZ-CUD participants. The oral dronabinol SCZ-CUD group, but not smoked THC SCZ-CUD group, performed worse than placebo on verbal learning (B = -9.89; 95% CI: -16.06, -3.18; P = .004) and attention (B = -0.61; 95% CI: -1.00, -0.23; P = .002). Every 10-point increment in serum THC + THCC ng/ml was associated with increased negative symptoms (0.40 points; 95% CI: 0.15, 0.65; P = .001; subscale ranges 7-49) and trends were observed for worse positive symptoms and performance in verbal learning, delayed recall, and working memory.

CONCLUSIONS

In people with SCZ-CUD, a modest single dose of oral THC was associated with worse cognitive functioning without symptom exacerbation several hours after administration, and a THC dose-response effect was seen for negative symptoms.

Late Reduction of Cocaine Cravings in a Randomized, Double-Blind Trial of Aripiprazole vs Perphenazine in Schizophrenia and Comorbid Cocaine Dependence

PURPOSE

Co-occurring schizophrenia spectrum disorder and International Statistical Classification of Diseases, 10th Revision cocaine dependence present a particularly destructive constellation that is often difficult to treat. Both conditions raise dopamine transmission effects in the brain. Traditional neuroleptics block dopamine receptors, whereas aripiprazole modulates dopamine activity as an agonist/antagonist. We tested whether dopamine modulation is superior to dopamine blocking in dual-diagnosis patients.

METHODS

In a randomized, double-blind, comparison design, cocaine-dependent schizophrenic subjects actively using cocaine received either aripiprazole or perphenazine in an 8-week trial. Primary outcome targeted cocaine-free urine sample proportions, whereas cocaine craving scores were a secondary variable.

RESULTS

Subjects (N = 44) randomized (n = 22 per group) did not differ at baseline. The proportion of cocaine-free urine samples did not differ by medication group. Contrasting weeks 3 to 5 vs 6 to 8 revealed significant late reductions in craving with aripiprazole. On the respective 5-point subscales, craving intensity decreased by 1.53 ± 0.43 (P < 0.0005) points, craving frequency by 1.4 ± 0.40 (P > 0.0004) points, and craving duration by 1.76 ± 0.44 (P > 0.0001) points.

CONCLUSIONS

A drug effect of aripiprazole on craving items appeared at week 6 of treatment, on average, and was not seen before that length of drug exposure. The data suggest that dopamine modulation reduces cocaine cravings but requires an acclimation period. To understand the mechanism of action better, a trial of depot aripiprazole may be useful. Clinically, a reduction in craving potentially offers a clearer focus for ongoing behavioral treatment. It may also offer a longer-term treatment effect with respect to the severity of relapse.

Cocaine Use and Sexual Risk Among Individuals With Severe Mental Illness

OBJECTIVE

Rates of HIV remain elevated in select populations such as those with severe mental illness and also among those who abuse cocaine, a vehicle through which risky sexual behavior may occur. The objective of the present narrative review was to synthesize the literature regarding stimulant use and its association with sexual risk among individuals with severe mental illness.

METHODS

This narrative review of the literature utilized Boolean search logic and the PsycINFO and PsycARTICLES databases to identify articles that explored the relationships among stimulant use, risky sexual behavior, and severe mental illness. Only one article was identified that examined a stimulant other than cocaine. Thus, the review was further limited to the impact that cocaine has on risky sexual behavior among those with severe mental illness.

RESULTS

Of the 87 abstracts obtained, 58 underwent a full text review and eight were included in the final review. Studies had a mean sample size of 110 and predominantly consisted of male (64%) outpatients. Study designs were largely cross-sectional and almost exclusively relied on retrospective participant report of sexual behavior and drug use. The extant literature indicates a positive association between cocaine and risky sexual behavior among those with a diagnosed severe mental illness. Risky behaviors associated with cocaine included reporting a greater number of partners as well as a higher degree of involvement in the sex trade. The positive association observed between cocaine and partner-related risk, however, did not extend to condom use.

CONCLUSIONS

Further research that utilizes better defined and operationalized constructs to investigate relationships among stimulant use, severe mental illness, and sexual risk, particularly condom use, is warranted and is necessary to advance the field.

Chronic non-fatal Datura abuse in a patient of paranoid schizophrenia: a case report

INTRODUCTION

A range of psychoactive substances used by patients suffering from schizophrenia varies and may include those which are fatal and may cause serious toxicity leading to death. We here present a case report of a patient suffering from paranoid schizophrenia, who was abusing Datura stramonium over a prolonged period.

CASE SUMMARY

A 32 year old male presented with aggressive behaviour, irritability for 6 years and regular intake of Datura seeds for 3 years. After taking detailed history and mental status examination (MSE), diagnoses of paranoid schizophrenia and mental and behavioral disorder due to use of hallucinogen were made. He had shown improvement on standard treatment with antipsychotics.

CONCLUSION

D. stramonium is recognized among emerging new psychoactive substances being used across the world. Among various theories we discuss self-medication hypothesis as a mediating factor for this case. Though D. stramonium is notorious for its life threatening sequelae, clinicians should be aware of its chronic abuse as self-medication.

Pharmacotherapy of Co-Occurring Schizophrenia and Substance Use Disorders

Substance use disorders, common in patients with schizophrenia, can lead to poor outcomes. Here we review the literature on the use of antipsychotics in patients with co-occurring schizophrenia and substance use disorder as well as evidence for the use of adjunctive pharmacological treatments targeting substance use in these patients. We also discuss a neurobiological formulation suggesting that the cooccurrence of these disorders may be related to a dysfunction in the dopamine mediated brain reward circuitry. Typical antipsychotics do not appear to decrease substance use in this population. Randomized, controlled trials provide some support for use of the atypical antipsychotic clozapine for co-occurring cannabis use disorder, naltrexone and disulfiram for alcohol use disorder, and also nicotine replacement therapy, sustained-release bupropion and varenicline for tobacco use disorder. Nonetheless, data regarding treatment in patients with these co-occurring disorders are still limited, and many studies reported to date have been either underpowered or did not include a control condition. Further research is needed to evaluate optimal pharmacotherapeutic strategies for this population.

Impaired functional connectivity of brain reward circuitry in patients with schizophrenia and cannabis use disorder: Effects of cannabis and THC

Cannabis use disorder (CUD) occurs in up to 42% of patients with schizophrenia and substantially worsens disease progression. The basis of CUD in schizophrenia is unclear and available treatments are rarely successful at limiting cannabis use. We have proposed that a dysregulated brain reward circuit (BRC) may underpin cannabis use in these patients. In the present pilot study, we used whole-brain seed-to-voxel resting state functional connectivity (rs-fc) to examine the BRC of patients with schizophrenia and CUD, and to explore the effects of smoked cannabis and orally administered delta-9-tetrahydrocannabinol (THC) on the BRC. 12 patients with schizophrenia and CUD and 12 control subjects each completed two fMRI resting scans, with patients administered either a 3.6% THC cannabis cigarette (n=6) or a 15 mg THC capsule (n=6) prior to their second scan. Results revealed significantly reduced connectivity at baseline in patients relative to controls, with most pronounced hypoconnectivity found between the nucleus accumbens and prefrontal cortical BRC regions (i.e., anterior prefrontal cortex, orbitofrontal cortex, and anterior cingulate cortex). Both cannabis and THC administration increased connectivity between these regions, in direct correlation with increases in plasma THC levels. This study is the first to investigate interregional connectivity of the BRC and the effects of cannabis and THC on this circuit in patients with schizophrenia and CUD. The findings from this pilot study support the use of rs-fc as a means of measuring the integrity of the BRC and the effects of pharmacologic agents acting on this circuit in patients with schizophrenia and CUD.

Schizophrenia and co-occurring substance use disorder: reward, olfaction and clozapine

Co-occurring substance use disorders (SUD), including alcohol, are common in schizophrenia (SZ) and are associated with poor outcome. Emerging data suggest that individuals with SZ have a dysfunctional brain reward circuit that may underlie their frequent use of alcohol and other substances, and further, that the atypical antipsychotic, clozapine (CLOZ), limits alcohol/substance use in these individuals, potentially by ameliorating this brain reward circuit dysfunction. To explore this hypothesis, reward functioning in a SZ sample with a history of co-occurring SUD, treated with either CLOZ (n=13) or typical antipsychotic agents (TYP), haloperidol or fluphenazine (n=14), as well as healthy controls (n=16), was evaluated through ratings of pleasurable and aversive odors, stimuli that are processed by several neural structures thought to play a key role in processing rewarding stimuli. Results suggest that CLOZ treatment is associated with broadening and strengthening the hedonic experience of these rewarding olfactory stimuli, both of a pleasant and unpleasant nature. This hedonic appraisal of odors appeared to be independent of odor perception (intensity ratings) and clinical symptoms. These preliminary findings provide important new data in support of the hypothesis that CLOZ ameliorates some aspects of abnormal brain reward functioning in individuals with co-occurring SZ and SUD. Further research may have valuable treatment implications for this population including interventions for other reward-associated deficits in learning, social interactions and other aspects of behavior and cognition.

Impact of substance use disorder on presentation and short-term course of schizophrenia

The aim of the present study was to compare a cohort of schizophrenia patients with substance use disorder (SUD) with a similar cohort of schizophrenia patients without SUD with regard to sociodemographic variables, clinical variables, psychopathology, anxiety symptoms, depressive symptoms, treatment outcome, and side effect profile of drugs. A total of 143 consecutive inpatients with ICD-10 DCR diagnosis of schizophrenia were included after obtaining informed consent. Patients were evaluated by a semistructured data sheet and Maudsley Addiction Profile. They were then rated by Positive and Negative Symptoms Scale, Calgary Depression Scale, Hamilton Anxiety Rating Scale, and Brief Psychiatric Rating Scale at presentation, three weeks, and six weeks. At three weeks and six weeks, they were also evaluated by UKU Side Effect Rating Scale. Substance abuse was detected in 63.6% schizophrenia patients. Nicotine was the commonest substance followed by cannabis and alcohol. Substance users had longer untreated illness and more depressive symptoms at presentation and six-week follow-up. Dual diagnosis patients had difficulty in abstraction at three and six weeks but not at presentation. Schizophrenia patients with SUD had more depressive symptoms. SUD appeared to mask abstraction difficulties at presentation. Schizophrenia patients with SUD should be carefully assessed for presence of depression.

Do motivation deficits in schizophrenia-spectrum disorders promote cannabis use? An investigation of behavioural response to natural rewards and drug cues

Deficits in incentive motivation are often present in both Schizophrenia Spectrum Disorders (SSD) and substance-use disorders. The current study aims to test whether the presence of such deficits confers vulnerability to cannabis use in individuals with SSD. SSD patients (n=35) and healthy controls (n=35) were each divided into a group with (n=20) and a group without (n=15) current cannabis use disorder. Subjects performed a behavioural task designed for schizophrenia patients in which they could seek exposure to pleasant and cannabis visual stimuli on the basis of internal representations of these stimuli. Intensity of cannabis use was assessed by self-report. SSD patients were significantly less likely than controls to exert effort to try to re-view pleasant stimuli but were not significantly less likely to work to avoid unpleasant stimuli. Lack of response to re-view pleasant stimuli significantly predicted higher subsequent cannabis self-administration in patients but not controls, after controlling for degree of prior exposure to cannabis. Deficits in incentive motivation may be an aspect of SSD which promotes cannabis use in this population.

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.

Effects of naltrexone on food intake and body weight gain in olanzapine-treated rats

Blockade of opioidergic neurotransmission contributes to reduction in body weight. However, how such blockade affects body weight gain (BWG) attributed to second generation antipsychotic agents (SGAs) has not yet been established. Here we examined the effects of an opioid receptor antagonist, naltrexone (NTX), on food intake and BWG associated with an SGA, olanzapine (OL). Four groups of Wistar Han IGS rats were treated for 28 days with either OL (2 mg/kg twice daily, intraperitoneal (IP)), a combination of OL (2 mg/kg twice daily, IP) + extended-release NTX (50 mg/kg, one-time, intramuscular (IM)), extended-release NTX (50 mg/kg, one-time, IM) or vehicle and their food intake and body weight were measured daily for the first nine days and every other day thereafter. Food intake and BWG that were increased by OL were decreased by the added NTX while NTX alone had no significant effects on food intake or on BWG. Plasma leptin concentrations were significantly elevated in the three groups receiving pharmacological agents, but did not differ among each other, suggesting that changes in leptin secretion and/or clearance alone would not explain the food intake and the body weight findings. Our results extend prior reports on anorexigenic effects of opioid antagonists by demonstrating that such effects may generalize to food intake increases and BWG arising in the context of OL pharmacotherapy.

Concomitant medication of psychoses in a lifetime perspective

OBJECTIVE

Patients treated with antipsychotic drugs often receive concomitant psychotropic compounds. Few studies address this issue from a lifetime perspective. Here, an analysis is presented of the prescription pattern of such concomitant medication from the first contact with psychiatry until the last written note in the case history documents, in patients with a diagnosis of psychotic illness.

METHODS

A retrospective descriptive analysis of all case history data of 66 patients diagnosed with schizophrenia or schizophrenia-like psychotic disorders.

RESULTS

Benzodiazepines and benzodiazepine-related anxiolytic drugs had been prescribed to 95% of the patients, other anxiolytics, sedatives or hypnotic drugs to 61%, anti-parkinsonism drugs to 86%, and antidepressants to 56% of the patients. However, lifetime doses were small and most of the time patients had no concomitant medication. The prescribed lifetime dose of anti-parkinsonism drugs was associated with that of prescribed first-generation but not second-generation antipsychotics.

CONCLUSIONS

Most psychosis patients are sometimes treated with concomitant drugs but mainly over short periods. Lifetime concomitant add-on medication at the individual patient level is variable and complex but not extensive.

Comorbid psychiatric and substance abuse disorders: recent treatment research

Psychiatric comorbidity is defined as the co-occurrence of a psychiatric disorder in a patient with a substance use disorder. Psychiatric disorders in substance abuse patients can antedate the substance use disorder or be a consequence of the substance abuse. There is emerging evidence that drug use in adolescence may alter the onset of certain psychiatric disorders in vulnerable individuals. Patients with concurrent comorbid disorders present special challenges for the substance abuse treatment system in terms of diagnosis and management because each disorder has the capability of exacerbating the other. This manuscript is a summary of an ISAM symposium that featured three speakers who discussed the following topics: 1. Etiology and treatment of comorbid psychiatric and substance use disorders in adolescents; 2. Treatment of ADHD and substance use disorders in adults; 3. Effects of substance abuse on the onset, severity, and treatment of schizophrenia. Recommendations for further research will be presented.

Negative symptoms are associated with less alcohol use, craving, and "high" in alcohol dependent patients with schizophrenia

BACKGROUND

Alcohol use disorders (AUDs) frequently co-occur with and exacerbate schizophrenia, yet the specific relationships between schizophrenia symptoms and alcohol use remain unclear.

METHODS

PANSS scores were correlated with measures of alcohol and other substance use in patients with schizophrenia-spectrum disorders and AUDs entering a trial of monitored naltrexone treatment. Data were analyzed from the first 80 participants; 55% had schizophrenia and 45% had schizoaffective disorder. All had AUDs; 95% had alcohol dependence and 5% alcohol abuse; 34% also had cannabis abuse/dependence and 31% cocaine abuse/dependence.

RESULTS

PANSS Negative scores were inversely correlated with Addiction Severity Index alcohol composite scores, alcohol craving, quality of alcohol "high" (euphoria), and with frequency of cannabis use. An exploratory analysis indicated that the negative symptoms that may most strongly correlate with less alcohol use, craving and/or euphoria were passive/apathetic social withdrawal, blunted affect, difficulty in abstract thinking, and stereotyped thinking. Higher PANSS Composite scores, indicating the predominance of positive over negative PANSS symptoms, correlated with more alcohol craving and cannabis use. Higher PANSS General scores were associated with more alcohol craving.

CONCLUSIONS

These findings extend previous reports of the association of negative schizophrenia symptoms with less alcohol and substance use to patients with AUDs and indicate that this relationship also includes less alcohol craving and less alcohol euphoria. The findings may also provide some initial evidence that specific negative symptoms may be keys to these relationships.

Pharmacotherapy of schizophrenia with comorbid substance use disorder--reviewing the evidence and clinical recommendations

Substance use disorder is the most common psychiatric comorbidity in schizophrenic patients, with prevalence rates of up to 65%. Recommendations for antipsychotic pharmacotherapy in schizophrenia are based on studies that excluded patients with this dual diagnosis. In the present comprehensive systematic review, the pharmacological studies performed in this subgroup of patients are summarised and discussed from the standpoint of evidence-based medicine. Unfortunately, randomized controlled studies, providing a high evidence level, in patients with this dual diagnosis are rare. Data, mainly based on open studies or case series, suggest superior efficacy for second generation antipsychotic agents (SGAs) (aripiprazole, clozapine, olanzapine, quetiapine, risperidone) with regard to improvement of distinct psychopathological symptoms, reduced craving and greater reduction of substance use compared with orally administered conventional antipsychotics (FGAs). Tricyclic antidepressants given adjunctive to antipsychotic maintenance therapy showed efficacy in reducing substance use and craving. The administration of anti-craving agents (naltrexone) led to a decrease of drug intake. Unfortunately, there is no clinical experience with acamprosate in schizophrenic patients with comorbid alcoholism. In conclusion, there are more theoretically based arguments for the preferential use of SGAs in schizophrenic patients with comorbid substance use disorder while the empirical evidence is weak. The early initiation of treatment with antidepressants, depending on the patient's psychopathology, as well as add-on medication with anti-craving agents should be considered.

Pharmakotherapie bei Schizophrenie und komorbider Substanzstörung

Substance use disorder is the most common psychiatric comorbidity in patients with schizophrenia, revealing prevalence rates of up to 65%. Recommendations of antipsychotic pharmacotherapy in schizophrenia are based on studies excluding patients with this double diagnosis. In this systematic review the available pharmacological studies in this subgroup of patients are summarised and discussed with regard to evidence-based medicine. Most available studies concern small sample sizes, and the level of evidence in those studies was low. Data suggest efficacy for second-generation antipsychotics (SGAs) (aripiprazole, clozapine, olanzapine, quetiapine, and risperidone) superior to orally administered conventional antipsychotics. Treatment with SGAs revealed superior improvement of distinct psychopathological symptoms, similarly to those studies excluding patients with comorbid substance abuse. In some studies reduced craving and increased reduction of substance abuse could be demonstrated. Tricyclic antidepressants (TCAs) added to antipsychotic maintenance therapy showed efficacy in reducing substance abuse and craving, whereas studies with other antidepressive agents (e.g. selective serotonin reuptake inhibitors) are lacking. Administration of the anti-craving agents naltrexone and disulfiram led to a decrease of drug intake in a few studies. Unfortunately no studies are available using acamprosate in patients with schizophrenia and comorbid alcoholism. In conclusion the preferential use of SGAs in patients with schizophrenia and comorbid substance use disorder is suggested, and the early initiation of concomitant treatment with TCAs (depending on current psychopathological status) and anti-craving agents has to be considered.

Substance abuse and schizophrenia: pharmacotherapeutic intervention

Substance use disorder is common in patients with schizophrenia and dramatically worsens their outcome. The typical antipsychotic medications, introduced more than 50 years ago, are effective for the treatment of psychosis but may have only limited efficacy in patients with these co-occurring disorders because patients continue to use substances while taking them. In preliminary studies, however, several of the atypical antipsychotic medications have shown promise for reducing alcohol and drug use in patients with schizophrenia. A neurobiological formulation is discussed, suggesting that the use of substances in patients with schizophrenia may be based on a dysfunction within the dopamine-mediated brain reward circuitry and that clozapine, in particular, may potentially ameliorate this dysfunction and lessen the desire for substance use. Medications for the treatment of alcohol use disorders, such as disulfiram, naltrexone, and acamprosate, as well as other adjunctive medications, may also be useful. Further studies are required to establish a solid evidence base of best practices for the use of medications in these patients.

Pharmacotherapy for schizophrenia and co-occurring substance use disorders

Substance use disorder (SUD) occurs commonly in patients with schizophrenia and is associated with a poor outcome. Despite this common co-morbid occurrence (and its negative impact on the course of schizophrenia), there have been very few studies assessing pharmacological strategies for optimal treatment of these patients. A number of theories have been advanced to help explain the high rate of substance use disorder in patients with schizophrenia. Our group has suggested that the brain reward circuit dysfunction model, which may incorporate aspects of all of these models, may help direct research aimed at developing new pharmacological treatments for patients with schizophrenia and co-occurring SUD. Although typical antipsychotic medications appear to be of limited value in these patients, emerging, but preliminary, data suggest that the atypical antipsychotics, particularly clozapine, may be particularly helpful. The role of adjunctive medications, such as those medications that have recently been shown to be useful for the treatment of alcoholism, may have a role in the treatment of these patients, although only naltrexone has, thusfar, been carefully tested in these comorbid patients. Further studies are indicated to assess the role of novel pharmacologic treatment strategies for these patients. Ultimately, any medication given to these patients will need to be prescribed within psychosocial treatment programs aimed at assisting these patients in limiting and ultimately ceasing substance use.