Background: Neurological conditions carry a high risk of depression. Given this risk, the Neurological Institute (NI) at Cleveland Clinic has initiated systematic screening for depression using the 9-item Patient Health Questionnaire-9 (PHQ-9) embedded within its electronic medical record and its data capture system, the Knowledge Program (KP)1.

Objective: We sought to (1) estimate the prevalence of depression among patients with epilepsy, stroke, and multiple sclerosis (MS); (2) identify risk factors for depression within each disease; and (3) determine differential risks and predictors across neurological disorders.

Methods: The KP1 database provided information on approximately 23,000 visits involving 7946 outpatients with epilepsy, stroke, or MS seen in neurology specialty clinics. The primary outcome measure was depression as defined as a PHQ-9 ≥ 10.

Results: Overall, the point prevalence of depression was 29.0%. For stroke, epilepsy, and MS, prevalence of depression was 23% (95% CI: 21-25%), 33% (95% CI: 31-35%), and 29% (95% CI: 28-30%), respectively. For all 3 conditions, increasing disease severity and decreased health-related quality of life were independent predictors of depression. In multivariable models, there was a significant interaction between age and condition, and condition with disease severity. In stroke and MS, increasing age was associated with reduced odds for depression, whereas in epilepsy, increasing age was associated with an increased odds for depression.

Conclusions: Although depression is common among patients with neurological disorders, our data suggest that predictors of depression such as age and disease severity varied by condition, supporting important possible phenomenological and pathophysiological differences of depression across these neurological conditions.