Declarative memory in patients with bipolar disorder and stimulant abuse receiving lamotrigine

Bipolar disorder (BPD) and stimulant use are both associated with cognitive deficits. Patients with BPD and substance use disorders have poorer cognition than patients with only BPD. No longitudinal studies have examined the impact of improvement in mood and reduction in substance use on cognition, specifically memory, in patients with BPD and substance abuse. We previously reported positive effects of lamotrigine on mood and drug use in patients with BPD and stimulant dependence. In a consecutive subset of these patients, declarative memory was assessed at baseline and at week 12. Lamotrigine titration up to 300 mg/day was accomplished over 10 weeks. Participants (n = 31) with BPD and cocaine/amphetamine dependence were assessed using the Mini International Neuropsychiatric Interview, Hamilton Rating Scale for Depression, Young Mania Rating Scale, Brief Psychiatric Rating Scale, Cocaine Craving Questionnaire, and Rey Auditory Verbal Learning Test (RAVLT) while receiving lamotrigine. Drug use was assessed through urine drug screens and self-report. Mood and drug use were assessed biweekly. Psychiatric symptoms improved and drug use decreased, but performance on the RAVLT, a measure of declarative memory, declined, primarily because patients were receiving concomitant psychotropic medications. Those receiving lamotrigine monotherapy showed little change in RAVLT scores. In summary, memory deficits in patients with BPD and stimulant dependence did not improve following reduction in drug use and improvement of mood. The combination of lamotrigine with other psychotropic medications may be associated with a decline in declarative memory performance in some persons.