Substance Use in Schizophrenia: Efficacy of Atypical Antipsychotics

Research Article

J Schizophr Res. 2014;1(1): 12.

Substance Use in Schizophrenia: Efficacy of Atypical Antipsychotics

Gianna Sepede1*, Marco Lorusso1#, Maria Chiara Spano1#, Giuseppe Di Iorio1,2, Giovanni Martinotti1,2, Rita Santacroce1, Rosa Maria Salerno1, Francesco Gambi1 and Massimo Di Giannantonio1,2

1Department of Neuroscience Imaging and Clinical Science, "G. D'Annunzio" University of Chieti, Italy

2Department of Mental Health, National Health Trust, Chieti, Italy

#Equally Contributed

*Corresponding author: Gianna Sepede, Department of Neuroscience Imaging and Clinical Science, ITAB - Institute for Advanced Biomedical Technologies, "G. D'Annunzio" University of Chieti, Via dei Vestini 33, 66013 Chieti Scalo (CH), Italy

Received: July 30, 2014; Accepted: August 08, 2014; Published: August 11, 2014

Abstract

Background: Substance Use Disorders (SUDs) are common among patients with schizophrenia and dramatically worsen their outcome. In the last years, the use of Atypical Antipsychotics (AAPs) in dual diagnosis has become an encouraging clinical strategy. Aim of the present paper is to provide a systematic literature review on efficacy and safety of AAPs use in schizophrenic patients with comorbid SUD.

Methods: We searched PubMed to identify original studies pertaining the use of AAPs in treating dual-diagnosed schizophrenic patients.

Results: We found 12 papers that met our inclusion/exclusion criteria:five randomized clinical trials, two open label trials and five observational studies. 1432 schizophrenic patients, 905 of them with a comorbid SUD, were involved. Olanzapine, Risperidone and Clozapine were the most prescribed AAPs; alcohol, cannabis and cocaine the most frequent substances of abuse. None of the selected studies was placebo-controlled: AAPs were compared to Typical Antipsychotics (TAPs) or one another. AAPs resulted usually, but not always, more efficacious than TAPs on substance related problems. In those studies comparing different AAPs, clozapine showed better results than other treatments, whereas no significant differences emerged between risperidone and olanzapine. In terms of safety, AAPs were usually well tolerated.

Conclusions: Our review suggests that AAPs, in particular clozapine, olanzapine and risperidone, may be a promising therapeutic option for schizophrenic patients with comorbid SUD. On the other hand, given the limited number of randomized controlled trials and the lack of placebo arms, further studies are needed to better address this point.

Keywords: Schizophrenia; Dual diagnosis; Atypical antipsychotics; Comorbidity; Substance abuse

Introduction

Substance Use Disorders (SUDs) are common among schizophrenic subjects: their lifetime prevalence of substance abuse is nearly 50%, three times higher than general population [1], and it seems to increase over time [2,3].

The substances most commonly abused by schizophrenic patients are alcohol (20%-60%), cannabis (12%-42%), cocaine (15%-50%) [4] and amphetamines (10%-25%) [5]; moreover, a high percentage of patients are poly-drug users [6].

Substance use increases the risk of schizophrenia in vulnerable individuals [7-9] and is associated with a younger age of symptoms onset with respect to schizophrenic patients without SUD [10,11].

Many hypotheses have been suggested to explain the elevated rates of substance abuse in schizophrenia. One hypothesis involves the principle of self-medication: patients may use substances to reduce psychiatric symptoms or side effects of medications [12-14]; this may be true especially when the SUD onset follows the development of psychotic symptoms [15]. This theory, however, does not explain the high rate of SUD preceding the clinical onset of schizophrenia [16]. A more recent hypothesis is that psychosis and substance use disordershare an altered function of dopamine-mediated reward-system [17], and common genetic alterations have been suggested to explain the high prevalence of SUD in schizophrenia [18-20].

A comorbid SUD in psychiatric patients significantly worsens their compliance, functional outcome and quality of life [21, 22] and the pharmacological treatment of dual diagnosis still appears as a challenge in psychiatric practice. In the last decades, Atypical Antipsychotics (AAPs) have largely replaced Typical Antipsychotics (TAPs) in the treatment of schizophrenia [23, 24], due to their efficacy and better tolerability. Nevertheless, their use in dual-diagnosed patients is still debated [25, 26]. Aim of the present paper is to provide a systematic literature review on efficacy and safety of AAPs use in schizophrenic patients with comorbid SUD.

Methods

We searched PubMed to identify original studies pertaining the use of AAPs in the treatment of schizophrenic patients with comorbid SUD. The following search words were used, both alone and in combination: schizophrenia, atypical antipsychotics, substance use, dual diagnosis, comorbidity.

The search was conducted on June 2nd, 2014 and yielded 135 records. Moreover, we manually checked the reference lists of the identified articles and we found 4 more potential studies, for a total number of 139 records. Inclusion criteria were the following: original articles (open label or double blind trials, prospective or retrospective observational studies) written in English, patients' age = 18 years, patients affected by schizophrenia with SUD, treatment with AAPs. Animal studies, reviews, commentaries, case reports, studies not enrolling dual-diagnosed patients or not including a treatment arm with AAPs were excluded.

By reading titles and abstracts, we excluded 118 records. By reading the full texts of the 21 remaining articles, we found 12 papers meeting our inclusion/exclusion criteria, and therefore included in the qualitative synthesis (Figure 1).

Citation: Sepede G, Lorusso M, Spano MC, Di Iorio G, Martinotti G, et al. Substance Use in Schizophrenia: Efficacy of Atypical Antipsychotics. J Schizophr Res. 2014;1(1): 12. ISSN:2471-0148