180. CORRELATION OF MOOD SYMPTOMS AND THE SEASONAL VARIATION OF VITAMIN D LEVELS IN TAIWANESE MOOD DISORDER PATIENTS AND HEALTHY INDIVIDUALS: A COMPARATIVE COHORT STUDY

Abstract Background Mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD), often exhibit mood fluctuations linked to seasonal changes. Vitamin D has been proposed as a biomarker influencing these patterns. Aims & Objectives This study investigates seasonal variations in vitamin D levels in individuals with mood disorders and healthy controls and explores their association with seasonal mood symptoms. Method This longitudinal study included individuals aged 20–70 diagnosed with MDD or BD according to DSM-IV criteria, along with healthy controls recruited from four outpatient clinics (2018–2021). Patients with schizophrenia, schizoaffective disorder, intellectual disabilities, or substance use disorders were excluded. Participants were followed for one year, with seasonal measurements of vitamin D levels. Concurrently, mood symptoms were assessed in the mood disorder groups using the Hamilton Depression Scale (HAMD), Beck Depression Inventory (BDI), and Young Mania Rating Scale (YMRS). Seasonal mood patterns were evaluated with the Seasonal Pattern Assessment Questionnaire (SPAQ), calculating General Seasonality Scores (GSS). Seasonal Affective Disorder (SAD) was defined as a General Seasonality Score (GSS) > 10, with seasonal variations in physiological signs causing moderate to severe impacts on daily life. Pearson correlations were analyzed between vitamin D levels and symptom severity. Results Among the 156 participants (49 with MDD, 52 with bipolar I, 12 with bipolar II, and 43 healthy controls), no significant differences in mean vitamin D levels were observed across diagnoses (bipolar I: 21.41ng/ml, bipolar II: 20.47ng/ml, MDD: 23.38ng/ml, healthy control: 21.01ng/ml). In bipolar I disorder, vitamin D levels showed significant negative correlations with HAMD (r = −0.253, p = 0.0017), BDI (r = −0.304, p < 0.001), YMRS (r = −0.170, p = 0.037), and GSS (r = −0.226, p = 0.005). For MDD, significant negative correlations were found with HAMD (r = −0.215, p = 0.013), BDI (r = −0.178, p = 0.041), and YMRS (r = −0.180, p = 0.039), but not with GSS (p = 0.438). In bipolar II disorder, a significant negative correlation was observed only with BDI (r = −0.178, p = 0.041), with no significant relationships detected for YMRS, HAMD, or GSS. In BD (combined bipolar I and II), significant correlations were observed between vitamin D levels and HAMD (r = −0.209, p = 0.004), BDI (r = −0.307, p < 0.001), and GSS (r = −0.210, p = 0.003), but not with YMRS. Patients with SAD exhibited stronger negative correlations between vitamin D levels and mood symptoms (YMRS: r = −0.29, p = 0.006; BDI: r = −0.308, p = 0.004) compared to non-SAD patients (YMRS: r = 0.009, p = 0.9; BDI: r = −0.137, p = 0.04). In healthy controls, no significant relationship was identified between vitamin D levels and GSS. Discussion & Conclusions Vitamin D levels, though not diagnostic markers, show potential as monitoring tools due to their negative correlation with mood symptom severity, particularly in seasonal mood patterns. Manic symptoms in unipolar depression correlated with vitamin D levels. The study emphasize the need for further research into vitamin D supplementation as a therapeutic strategy for mood disorders with seasonal variation.