Prevalence of depression in amyotrophic lateral sclerosis and other motor disorders

Background: Research suggests the prevalence of severe depression in ALS is < 20%. In contrast, studies have reported that severe depression affects 40-50% of patients with other neurodegenerative motor conditions (e.g. multiple sclerosis, Parkinson's disease and Huntington's disease). The comparison with such disorders has generated a clinical impression that patients with ALS have surprisingly low rates of depression. However, comparisons with such disorders do not take into account the markedly different pathological, physical and behavioural profiles associated with these disorders. To assess further the extent to which ALS is associated with a low prevalence of depression, we compared the prevalence of depression in patients with ALS to that in patients with neuromuscular disorders with more comparable disease profiles. Methods: The Beck Depression Inventory-II (BDI-II), the Major Depression Inventory (MDI), the Hospital Anxiety and Depression Scale (HADS) and the ALS Functional Rating Scale-Revised were sent to 212 patients from a tertiary referral Motor Nerve Clinic in London, UK. Results: Data were obtained from 51 people with ALS and 39 with other neuromuscular disorders. The non-ALS group included patients diagnosed with disorders that are characterized by motor neurone dysfunction and/or a decline in everyday function. Analyses revealed no between-group differences on severity and prevalence rates of depression according to the BDI-II, HADS Depression Subscale and MDI. Conclusions: Our findings do not support the impression that patients with ALS have lower rates of depression than patients with other varied neuromuscular disorders.