Prevalence and risk factors of bipolar disorder in central nervous system autoimmune demyelinating diseases

BACKGROUND: Affective disorders, including bipolar disorder (BPD), are increasingly recognized in patients with multiple sclerosis (pwMS), yet their comparable prevalence across MS subtypes and in neuromyelitis optica spectrum disorder (NMOSD) remains unclear. This study aimed to estimate the prevalence of BPD among patients with MS and NMOSD and to identify clinical and demographic factors associated with increased BPD risk. METHODS: We conducted a cross-sectional study involving 4,460 patients with MS and 299 patients with NMOSD. Psychiatric assessments were performed using structured interviews based on DSM-IV criteria. Demographic, neurological, and treatment data were collected from medical records and clinician evaluations. Multivariate logistic regression was used to assess factors associated with BPD, including disease subtype, disability level (EDSS), and clinical presentation. RESULTS: The overall prevalence of BPD was 3.07%, with the highest rate in SPMS (5.63%), followed by NMOSD (4.68%). The risk of BPD was comparable among NMOSD vs. MS patients (OR:1.15; 95%CI:0.60-2.17). Among pwMS, RRMS (2.48%) and PPMS (1.42%) had statistically comparable rates of BPD (OR: 0.55; 95%CI: 0.17-1.76); however, SPMS patients had highest prevalence of BPD that was statistically greater than RRMS (OR: 2.32; 95%CI: 1.57-3.44). Higher EDSS, single relationship status, addiction, smoking, and cerebellar symptoms at onset were also associated with higher likelihood of BPD. CONCLUSIONS: Higher disability in SPMS, early cerebellar involvement, and psychosocial factors were associated with higher odds of BPD. These findings underscore the need for routine psychiatric screening and tailored support strategies in high-risk subgroups.