Longitudinal Relationships Among Intrinsic Motivation and Depression in Adults with Schizophrenia and Comorbid Substance Use Disorders: The Role of Gender in Recovery

Background and Purpose: Comorbid substance use disorders (SUDs) are common in people with schizophrenia. Despite the growing interest in studying this population, little attention has been paid to women as a subgroup with unique treatment needs. The studies examining gender differences in schizophrenia show that women have more severe depressive symptoms, but make faster progress in treatment, and tend to exhibit better outcomes than men.  While such findings suggest that men and women may have unique treatment needs, few studies have identified the factors contributing to these differences.  Intrinsic motivation has received recent attention as an important factor in the treatment and recovery of schizophrenia. These deficits not only reduce a person’s capacity to engage in meaningful tasks, but also have a negative impact on outcomes. Women with schizophrenia and comorbid SUDs may have higher levels of intrinsic motivation than men, allowing for such women to experience positive outcomes despite severe depression. For a sample of adults with schizophrenia and comorbid SUDs, we examined the longitudinal impact of intrinsic motivation on 1-year depression recovery and its patterns in men and women.   

Methods: A total of 536 men (n = 450) and women (n = 86) with schizophrenia and comorbid SUDs completed the Calgary Depression Scale at baseline, 6-months, and 1-year for the Clinical Antipsychotic Trials of Intervention Effectiveness.  Intrinsic motivation was measured by the sum of three items (purpose, curiosity, and motivation) taken from the Quality of Life Scale. Growth curve models examined the longitudinal impact of motivation with depression.        

Results: Participants experienced, on average, significant depression recovery over 1-year (p < .001), but no longitudinal differences were observed between motivation with depression in the overall sample, F(1, 527) = 0.97, p = .324. Variability in these longitudinal patterns became evident upon examining the moderating effects of gender, as women with low motivation had the most severe depressive symptoms at baseline, but showed the fastest rates of depression recovery over 1-year compared to all other groups observed, F(1, 525) = 11.64, p < .001.  While men with high motivation demonstrated significantly faster rates of depression recovery than men with low motivation F(1, 443) = 5.43, p = .020, only sub-threshold differences were observed in the 1-year rates of change between motivation with depression in women F(1, 75) = 3.63, p = .060.        

Conclusions and Implications: Men and women with schizophrenia and comorbid SUDs both experienced recovery from depression over 1-year, yet women with low intrinsic motivation experienced more severe depression, and recovered at faster rates compared to men and women with high levels of intrinsic motivation. Our results suggest that high intrinsic motivation may lead to faster depression recovery for men but not for women. While future research will need to further examine the specific role of intrinsic motivation in attenuating depression, our findings underscore the need for social workers to adapt motivational interventions to the unique needs of men and women with schizophrenia, paying particular attention to depressive symptomatology and its potential impact on recovery.