Substance use, medication adherence and outcome one year following a first episode of psychosis

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Abstract

Both substance use and poor medication adherence are associated with poor outcome in psychosis. To clarify the contributions of substance use and poor medication adherence to poor outcome in the year following a first episode of psychosis, 205 patients were evaluated for use of tobacco, alcohol, cannabis and stimulants at their psychosis onset, and in a 1-year follow-up. Data on medication adherence and symptom remission were also collected. Patients had high rates of overall substance use before (37–65%) and after psychosis onset (45–66%). 44% showed poor medication adherence and 55% did not reach remission from psychosis. Nicotine dependence and cannabis use after psychosis onset significantly predicted both poor medication adherence and non-remission, and poor medication adherence mediated the effects of these substances on non-remission. In conclusion, medication adherence lies on the causal pathway between nicotine dependence and cannabis on the one hand and non-remission on the other.

Introduction

A number of studies have evaluated the impact that poor adherence to antipsychotic medication has on quality of life and hospitalizations in patients with psychosis (Gray et al., 2002, King et al., 2014, Park et al., 2014). Thus, poor medication adherence in patients following the first episode of psychosis (FEP) is associated with more frequent readmissions (Caseiro et al., 2012, Verdoux et al., 2000), and a greater risk of relapse (Kahn et al., 2008, Malla et al., 2006, Novak-Grubic and Tavcar, 2002).

Rates of poor adherence in FEP studies have been reported to range up to 71% (Hill et al., 2010, Levy et al., 2012, Miller et al., 2011). Use of substances, including cannabis and alcohol, has been found in several studies to be associated with poor medication adherence (Faridi et al., 2012, Hill et al., 2010, Lambert et al., 2010, Miller et al., 2009), as have a number of other demographic and clinical factors (Hill et al., 2010, Lambert et al., 2010). Furthermore, comorbid substance use has emerged as one of the greatest obstacles to the effective treatment of persons with psychosis; substance use is a risk factor for both poor medication adherence and dropout from treatment. Moreover, some studies suggest a dose–response relationship between severity of substance use and medication adherence rates (Dixon, 1999, Miller et al., 2009, Wade et al., 2007).

Two major limitations of the published data on substance use disorder and poor medication adherence are the small sample size of most studies and the narrow focus, usually on use of only one substance. In addition, the relation of poor adherence to tobacco smoking has not to date been investigated. This is important given that tobacco smoking is highly prevalent among psychotic patients, and there have been recent suggestions that tobacco smoking may be a risk factor for both onset (Gurillo et al., 2015) and outcome (Krishnadas et al., 2012) of psychosis.

In a one year follow-up of first episode psychosis patients, we obtained detailed information on the most commonly used substances among psychiatric patients, including tobacco, alcohol, cannabis and stimulants (such as amphetamines) both at baseline and during their subsequent clinical contact. Therefore the strength of our study is the ability to address the following hypotheses: 1. substance use following illness onset (tobacco, alcohol, cannabis and other stimulants) impairs medication adherence; 2. Substance use is associated with poor outcome at 1 year follow-up, and poor medication adherence mediates this effect.

Section snippets

Study design and sample

Participants were recruited as part of the Biomedical Research Centre (BRC) Genetics and Psychosis (GAP) and the Physical Health and Substance Use Measures (PUMP) studies carried out at the Institute of Psychiatry, Psychology and Neuroscience, London (Di Forti et al., 2009). All patients presenting to the Adult Psychiatric services (18 years < age < 65 years) of the South London and Maudsley NHS Foundation Trust between December 2005 and October 2010 with their first episode of psychosis (FEP) who

Socio-demographic characteristics

Out of 205 FEP patients on whom we obtained complete data at 1 year, 63.4% were male. There were no significant differences between those in whom complete data were obtained (N = 205) and those in whom it was not (N = 256) in terms of gender, age at first contact, ethnicity, relationship status, employment status, education level and diagnosis (all p > 0.1). The average age at first contact with psychiatric services for psychotic disorder was 29.6 years (± SD, ± 9.9 years). 35% of the FEP were White, 43%

Discussion

To our knowledge, this is the first study to systematically examine the association between use of the most common substances before and after psychosis onset, and clinical outcome over a one-year period in patients suffering their first episode of psychosis. The results indicate that both nicotine dependence and use of cannabis in the first year after psychosis onset affect medication adherence; furthermore, poor medication adherence is a strong predictor of non-remission. Finally, nicotine

Role of the funding source

This paper summarizes independent research funded by the UK National Institute for Health Research (NIHR) Specialist Biomedical Research Centre for Mental Health, South London and Maudsley (SLAM) and the Institute of Psychiatry at King's College London, The Psychiatry Research Trust, the Maudsley Charity Research Fund, the European Community's Seventh Framework Program (grant agreement No. HEALTHF2-2009-241,909; Project EU-GEI), and the Improving Physical health and Substance Use in Severe

Contributors

Dr. Di Forti had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: all authors. Acquisition, analysis, or interpretation of data: all authors. Drafting of the manuscript: all authors. Critical revision of the manuscript for important intellectual content: all authors. Statistical analysis: M. Colizzi and MizanurKhondoker. Administrative, technical, or material support: R.

Conflict of interest

DrGaughran has received honoraria for advisory work and lectures from Roche, BMS, Lundbeck, and Sunovion and has a family member with professional links to Lilly and GSK.

Professor Murray has received honoraria for lectures from Roche, Lundbeck and Sunovia. All other authors report no biomedical financial interests or potential conflicts of interest.

Acknowledgments

This study has been carried out with the support of: 1. The Genetic and Psychotic Disorders (GAP) Study, Institute of Psychiatry, King's College London; 2.The South London and Maudsley (SLaM) Mental Health NHS Foundation Trust.

References (46)

  • R.M. Murray et al.

    Different dopaminergic abnormalities underlie cannabis dependence and cannabis-induced psychosis

    Biol. Psychiatry

    (2014)
  • V. Novak-Grubic et al.

    Predictors of noncompliance in males with first-episode schizophrenia, schizophreniform and schizoaffective disorder

    Eur. Psychol.

    (2002)
  • M.J. Zvolensky et al.

    Big five personality factors and cigarette smoking: a 10-year study among US adults

    J. Psychiatr. Res.

    (2015)
  • J. Addington et al.

    Patterns, predictors and impact of substance use in early psychosis: a longitudinal study

    Acta Psychiatr. Scand.

    (2007)
  • A. Agrawal et al.

    The co-occurring use and misuse of cannabis and tobacco: a review

    Addiction

    (2012)
  • Z. Atakan

    Cannabis use by people with severe mental illness — is it important?

    Adv. Psychiatr. Treat.

    (2008)
  • T. Babor et al.

    AUDIT — The Alcohol Use Disorders Identification Test: Guidelines for Use in Primary Health Care

    (1989)
  • R.M. Baron et al.

    The moderator-mediator variable distinction in social psychological research: conceptual, strategic, and statistical considerations

    J. Pers. Soc. Psychol.

    (1986)
  • C.M. Cassidy et al.

    Validation of the alcohol use disorders identification test and the drug abuse screening test in first episode psychosis

    Can. J. Psychiatr.

    (2008)
  • E.L. Coldham et al.

    Medication adherence of individuals with a first-episode of psychosis

    Acta Psychiatr. Scand.

    (2002)
  • M. Colizzi et al.

    Interaction between DRD2 and AKT1 genetic variations on risk of psychosis in cannabis users: a case–control study

    NPJ Schizophr.

    (2015)
  • M. Colizzi et al.

    Interaction between functional genetic variation of DRD2 and cannabis use on risk of psychosis

    Schizophr. Bull.

    (2015)
  • C.A. Depp et al.

    Current smoking is associated with worse cognitive and adaptive functioning in serious mental illness

    Acta Psychiatr. Scand.

    (2015)
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