Proof-of-concept trial of an α7 nicotinic agonist in schizophrenia

Context: The alpha 7 nicotinic acetylcholine receptor gene, CHRNA7, is associated with genetic transmission of schizophrenia and related cognitive and neurophysiological sensory gating deficits. Cognitive dysfunction is responsible for significant psychosocial disability in schizophrenia. Nicotine, a low-potency agonist at the alpha 7 receptor, has some positive effects on neurophysiological and neurocognitive deficits associated with schizophrenia, which suggests that more effective receptor activation might meaningfully enhance cognition in schizophrenia. Objectives: To determine if 3-[(2,4-dimethoxy) benzylidene] anabaseine (DMXB-A), a natural alkaloid derivative and a partial alpha 7 nicotinic cholinergic agonist, significantly improves neurocognition, and to assess, by effects on P50 auditory evoked potential inhibition, whether its neurobiological actions are consistent with activation of alpha 7 nicotinic receptors. Design: Randomized, double-blind crossover trial of 2 drug doses and 1 placebo. Setting: General clinical research center. Patients: Twelve persons with schizophrenia who did not smoke and were concurrently treated with antipsychotic drugs. One person was withdrawn because of a transient decrease in white blood cell count. Intervention: Administration of DMXB-A. Main Outcome Measures: Total scale score of the Repeatable Battery for the Assessment of Neuropsychological Status and P50 inhibitory gating. Results: Significant neurocognitive improvement was found on the Repeatable Battery for the Assessment of Neuropsychological Status total scale score, particularly for the lower DMXB-A dose compared with placebo. Effects were greater than those of nicotine in a similar study. Significant improvement in P50 inhibition also occurred. Patients generally tolerated the drug well. Conclusions: An alpha 7 nicotinic agonist appears to have positive effects on neurocognition in persons with schizophrenia. Longer trials are needed to determine the clinical utility of this novel treatment strategy.