Development and validation of a scale for assessing reasons for substance use in schizophrenia: The ReSUS scale
Abstract
This paper reports on the development of a questionnaire to assess self reported reasons for substance use in schizophrenia: the ‘reasons for substance use in schizophrenia’ (ReSUS) scale and explores the relationship between reasons for use, psychiatric symptoms and substance use in a sample of 230 people with psychosis. Principal components analysis revealed three subscales: “coping with distressing emotions and symptoms', “social enhancement and intoxication” and “individual enhancement”. Predicted associations were partially supported. ‘Coping’ reasons for use were related to positive symptoms, general symptoms, global functioning, depression and suicide behaviour as well as substance use (quantity of use and problems related to use). ‘Individual enhancement’ reasons were related to positive symptoms, to global functioning and to negative consequences of substance use. ‘Social enhancement and intoxication’ reasons were related to negative consequences of use but not to psychopathology. The findings suggest that the ReSUS is a reliable and valid instrument which can be used to explore self reported reasons for substance use and their relationship to psychotic symptoms in people with schizophrenia and other psychotic disorders.
Introduction
Around half of all people with a diagnosis of schizophrenia use drugs or alcohol (Regier et al., 1990). This comorbidity has been associated with a range of adverse clinical and social outcomes including more positive symptoms (Pencer & Addington, 2003), more relapses and hospitalizations (Linszen, Dingemans, & Lenior, 1994), increased aggression and violence (Cuffel, Shumway, Choulgian, & MacDonald, 1994) and higher rates of homelessness and housing instability (Drake, Osher, & Wallach, 1991). Significantly, these adverse outcomes occur at lower levels of intake in people with schizophrenia than in the general community (Drake, Osher, & Wallach, 1989). A better understanding of the reasons why people with schizophrenia use drugs and alcohol is essential if effective interventions aimed at reducing that use are to be developed.
People with a diagnosis of schizophrenia who also use drugs and alcohol report using substances for many different reasons. Research in this area has consistently shown that drugs and alcohol are used for many of the same reasons that people in the general population use them for: to increase pleasure, to fit in with others and to alleviate negative affective states such as boredom and depression (Addington and Duchak, 1997, Baker et al., 2002, Dixon et al., 1991, Fowler et al., 1998, Gearon et al., 2001, Goswami et al., 2004, Green et al., 2004, Schofield et al., 2006, Spencer et al., 2002). There is less consensus about whether people use substances for reasons directly related to schizophrenia however (as suggested by Khantzian, 1985, Khantzian, 1997), either in terms of psychotic symptoms, the distress associated with those symptoms or the side effects of neuroleptic medication. Only a handful of studies have reported that people experiencing psychosis report using substances to self medicate (Addington and Duchak, 1997, Gearon et al., 2001, Goswami et al., 2004, Spencer et al., 2002) but because of sampling and methodological differences (in the way that dual diagnosis was defined; the diagnostic criteria used for substance use and the variety of measures to assess reasons for use) it is difficult to draw firm conclusions about these results.
In an attempt to address some of the methodological limitations of the earlier self report studies Gregg, Haddock and Barrowclough (2009) used Q methodology (Stephenson, 1953) to examine reasons for use by people with a diagnosis of schizophrenia and current comorbid substance use. Q methodology requires participants to sort statements (in this case reasons for use) by placing them on a structured response grid (the Q grid, See Fig. 1). Q sorts are then analysed using a form of factor analysis in which each person's sort is correlated with all of the other sorts. The resultant factors consist of clusters of individuals who sorted statements in similar ways. Three sub groups of substance users were identified from the Q sorts: one group used drugs or alcohol primarily for enhancement purposes: to relax and to have a good time with others; to feel good and to celebrate. They endorsed the social aspects of substance use and used them to conform to their peer group, drinking alcohol or using drugs to fit in and when they felt under pressure from others. A second group used substances for ‘self improvement’ purposes and to intensify their experiences. They used drugs and alcohol in order to feel more creative, self aware, motivated and confident. The final group used drugs and alcohol to regulate negative affect and to alleviate or cope with the positive symptoms of schizophrenia: they used when they were feeling depressed, stressed, anxious, lonely and bored and when they were experiencing unpleasant thoughts; feeling suspicious or paranoid or were hearing voices. More than a third of the sample overall reported using substances when they were feeling paranoid or were hearing voices, providing some support for Khantzian, 1985, Khantzian, 1997) self medication hypothesis.
It is possible that different determinants of substance use may be related to distinct patterns of alcohol and drug consumption, to symptom severity and to motivation to change. There is already some evidence to suggest that this is the case e.g. Spencer, Castle, and Michie (2002) found that ‘coping with unpleasant affect’ motives significantly predicted quantity of recent use, problems related to that use and readiness to change in a sample of 69 patients with psychotic disorders. They also found that ‘enhancement’ motives predicted levels of recent use and ‘relief of positive symptoms and medication side effects’ motives predicted substance use dependence. Spencer, Castle, and Michie (2002) also found that ‘total motives’ (the sum of the five motive subscales they reported) were predicted by both negative symptoms and by global symptom severity scores (assessed using the Brief Symptom Inventory). However they did not assess the impact of symptoms on individual motive subscales. Likewise Gregg, Haddock, and Barrowclough (2009) did not assess current psychiatric symptoms and were therefore not able to examine the links between the three substance use profiles they identified and current psychiatric symptomatology. Additionally, few studies have examined reasons for use in the context of the known demographic risk factors such as age, gender and socioeconomic status. Gregg, Haddock, and Barrowclough (2009) found that the women in their sample were more likely to be using substances for ‘coping’ reasons than men but this has not been reported elsewhere.
Further research is necessary to explore the extent to which different reasons for use are related to demographic variables, to patient symptomatology, different patterns of substance use and to motivation to change. If relationships between these variables are confirmed, this could potentially have significant treatment implications.
The aim of the current study was to explore these relationships in a large sample of people diagnosed with schizophrenia or another psychotic disorder who also met criteria for current alcohol or substance abuse or dependence. Because the Q sort procedure used by Gregg, Haddock, and Barrowclough (2009) can take 30–60 min to administer its usefulness in a research context when administered as part of a battery of assessments is limited. We therefore developed a new questionnaire measure: the ‘reasons for substance use in schizophrenia’ (ReSUS) scale using some of the items from Gregg, Haddock, and Barrowclough's (2009) Q methodology study and present the psychometric properties of this new questionnaire here. We examined whether the subscales of the ReSUS were related to demographic variables, psychopathology, current levels of substance use, consequences of use and readiness to change. We hypothesised that:
- a)
The ReSUS scale would be a valid and reliable measure for assessing reasons for use in people with schizophrenia and other psychotic disorders
- b)
The ReSUS subscales would be similar to those identified by Gregg, Haddock, and Barrowclough (2009)
- c)
Reasons for use would be related to gender, with females being more likely to use substances for ‘coping’ reasons for use than males
- d)
Reasons for use would be related to both quantity of substance use, with higher scores on the ReSUS subscales being associated with higher quantities of use, and problems associated with substance use, with higher ReSUS scores being associated with more self reported negative consequences
- e)
Reasons for use would be related to psychiatric symptomatology with higher ReSUS scores being associated with more symptoms. Specifically, we predicted a positive correlation between ‘coping’ reasons for use (i.e. the use of substances to cope with or alleviate negative affective states and positive symptoms) and both positive and general symptoms (as measured by the Positive and Negative Syndrome Scales (PANSS; Kay, Fiszbein, & Opler, 1987).
Section snippets
Participants
A total of 230 participants took part in the study. The majority of participants (N = 195) were taking part in a randomized controlled trial involving patients with psychosis and substance use disorder (The MIDAS trial: Motivational Interventions for Drugs & Alcohol misuse in Schizophrenia. http://www.midastrial.ac.uk), 82 completed the questionnaire as part of their baseline assessment and an additional 113 completed it as part of their 12 month follow up. The remaining 35 participants had taken
Participant characteristics
The sample consisted of 205 (89.1%) males and 25 (10.9%) females with a mean age of 37.3 years (SD = 9.5). The majority (195, 84.8%) described themselves as white and most were unemployed (221, 96.1%). Two out of five (99, 43.1%) were living alone at the time of the assessments, one third (76, 33%) were living with a partner or other family members and the remainder (55, 23.9%) were living in shared accommodation (including hostels) with non family members. The average age at which participants
Discussion
The ReSUS is a valid and reliable measure for assessing reasons for substance use in people with schizophrenia and other psychotic disorders. Each of items in the ReSUS questionnaire was endorsed by at least a third of participants confirming the relevance of the scale's items for people with psychosis and the three subscales demonstrated good levels of internal consistency and stability over time. Analyses examining associations between the ReSUS subscales, psychopathology and substance use
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