Clinical correlates of lithium response in patients with bipolar disorder on long-term lithium therapy

BACKGROUND: Lithium continues to be one of first-line prophylactic agents for bipolar disorder (BD) but only about one-third of patients are excellent responders. Studies have described various clinical correlates of treatment response but Indian literature is limited. AIM: to assess the relationship of clinical variables to lithium response in subjects with BD on long-term prophylaxis METHODOLOGY: This was a cross-sectional, observational study of 40 subjects, aged 18-60 years, with DSM-5 BD type I, currently in remission. Subjects were included if they were on regular and long-term lithium for atleast one year or more. All subjects were screened using MINI 7.0 to exclude co morbidities and standard scales (YMRS≤4, HAM-D<8) to establish euthymia. Subjects were assessed using clinical proforma, NIMH Life Chart Method, Alda Lithium Response Scale (LRS) and IGSLI scale for typical/atypical features. RESULTS: Mean age for sample was 38.28 ±10.41 years (72.5% males). Mean illness duration was 13.84±9.23 years, with average onset at 24.40±8.21 years. Mean duration on lithium was 5.49±4.11 years (1-18 years) The LRS total (A-B) score showed a significant positive correlation to IGSLI typical features score (p=0.003), time since remission (p=0.034) and a significant negative correlation to IGSLI atypical features score (p=0.019) and age of onset of BD (p=0.037). There was a trend towards poorer lithium response with higher BMI (p=0.052) CONCLUSION: The clinical course characterized by an early age of onset and more atypical features (via. more manic than depressive episodes, presence of residual symptoms, mood incongruent psychotic features) appear to respond poorer to lithium.