Does the addition of lamotrigine to risperidone improve psychotic symptoms and cognitive impairements in chronic schizophrenia?

Shahin Akhondzadeh, K Mackinejad, SA Ahmadi-Abhari and ZM Alem

Background: Cognitive deficits are central features of schizophrenia, and cognitive dysfunction has been identified as a major determinant of long-term outcome and quality of life. It has been reported that lamotrigine, a mood stabilizer that inhibits glutamate release, can augment clozapine treatment in patients with chronic refractory schizophrenia. In addition, lamotrigine, unlike most antipsychotic drugs, can reverse psychotomimitic symptoms induced by ketamine and it may improve some aspects of cognitive dysfunction associated with schizophrenia such as attention, learning and memory.
Objectives: The objective of the present study was to assess the efficacy of lamotrigine as an adjuvant agent in the treatment of patients with chronic schizophrenia and in particular its effect on cognitive performance (attention) in an 8 week double blind and placebo controlled trial.
Method: Eligible participations in the study were 36 patients with schizophrenia. All patients were inpatients and were in the active phase of the illness, and met DSM-IV criteria for chronic schizophrenia. Patients were allocated in a random fashion, 18 to risperidone 6 mg/day plus lamotrigine 150 mg/day and 18 to risperidone 6 mg/day plus placebo.
Results: Although both protocols significantly decreased the score of the positive, negative and general psychopathological symptoms over the trial period, the combination of risperidone and lamotrigine showed a significant superiority over risperidone alone in the treatment of negative symptoms, general psychopathology symptoms as well as PANSS total scores. In addition, patients’ attention improved significantly in the lamotrigine group on the Stroop color naming subtest (time and error). There were no significant differences between the two groups in terms of extrapyramidal symptoms and observed side effects.
Conclusions: The present study indicates that lamotrigine is as a potential adjunctive treatment strategy for chronic schizophrenia and it may improve the attention domain of cognition impairment associated with schizophrenia.