Multiple sclerosis (MS) is considered the most common disabling neurological condition in young people, and it can significantly affect the quality of life of those living with the condition. Mental illness is an important dimension of MS (Feinstein, 2004; Rodgers & Bland, 1996). People with MS have an elevated prevalence of anxiety disorders (Korostil & Feinstein, 2007), psychotic and mood disorders (Patten, Svenson, & Metz, 2005b). The objectives of this study were to estimate the incidence and to conduct an exploratory analysis on the potential determinants of incidence of depression in MS.
Participants in this prospective cohort study (n=188) were followed for six months, starting with two baseline risk factor assessments then completing a depression screening instrument, the PHQ-9, every 2 weeks. At monthly intervals, information was collected on potential risk factors, using standard items from existing validated scales and instruments. Associations were estimated using prevalence ratios (PR) and hazard ratios (HR). A response feature analysis used standard deviation of total depression scores to categorize participants in an alternative way to the typical depression high/low cut-point measures.
Baseline cross-sectional analyses found a depression prevalence estimate of 22% using the traditional PHQ-9 cut-point of 10. Predictors of incidence included low self-esteem (HR=4.9), perceived inability to cope with demands of daily life (HR=5.4) low self-efficacy (HR=5.0) and task oriented coping (HR=0.2). The response feature analysis found there is a group of non-depressed participants with high PHQ-9 score variability that shares some risk factors with the depressed patients.
These results indicate depression in MS exhibits a risk factor profile similar to that of depression in the general population, with the additional impact of MS illness-related factors. Depression in MS is often regarded as being neurologically induced due to brain lesions, inflammation or axonal loss. While these results do not obviate this possibility, they provide a clear indication that depression in MS exhibits a risk factor profile characterized prominently by psychological and social factors. Future research should adopt a greater focus on such determinants, particularly coping with stress style, which may provide unrecognized opportunities for prevention and/or treatment of depression in this population.