RESUMEN
RATIONALE: Cognitive symptoms have increasingly been recognized as an important target in the development of future treatment strategies in schizophrenia. The nicotinergic neurotransmission system has been suggested as a potentially interesting treatment target for these cognitive deficits. However, previous research yielded conflicting results, which may be explained by several methodological limitations, such as the failure to include both a group of smoking and non-smoking schizophrenic patients, the use of only a single nicotine dose, and the inclusion of a very limited cognitive battery. OBJECTIVES: The present study aims at investigating the cognitive effects of nicotine in schizophrenia while addressing these methodological issues. METHODS: In a double-blind placebo-controlled randomized crossover design, cognitive effects are assessed in smoking (n =16) and non-smoking (n =16) schizophrenic patients after receiving active (1 or 2 mg) or placebo oromucosal nicotine spray. RESULTS: A modest improving effect of nicotine on attention in the smoking but not the non-smoking group was found. No enhancing effects were found on measures of visual memory, working memory, processing speed, psychomotor speed, or social cognitive functioning in either patient group. CONCLUSIONS: These findings suggest that the nicotinic receptor only has limited value as a cognitive treatment target in schizophrenia.
Asunto(s)
Trastornos del Conocimiento/tratamiento farmacológico , Nicotina/administración & dosificación , Agonistas Nicotínicos/administración & dosificación , Nootrópicos/administración & dosificación , Esquizofrenia/fisiopatología , Psicología del Esquizofrénico , Adulto , Trastornos del Conocimiento/fisiopatología , Estudios Cruzados , Método Doble Ciego , Femenino , Humanos , Modelos Lineales , Masculino , Pruebas Neuropsicológicas , Nicotina/sangre , Agonistas Nicotínicos/sangre , Nootrópicos/sangre , Desempeño Psicomotor/efectos de los fármacos , Desempeño Psicomotor/fisiología , Esquizofrenia/tratamiento farmacológico , Fumar/fisiopatología , Fumar/psicologíaRESUMEN
BACKGROUND: Nicotine receptor agonists are drugs that may be useful for the treatment of cognitive symptoms in schizophrenia. AIM: By studying the relevant literature we want to investigate to what extent nicotine enhances cognition in patients with schizophrenia and to find out which domains are affected. We also attempt to identify the obstacles that might impede the use, in the future, of nicotine receptor agonists. In addition, we aim to present the most likely neurobiological working mechanism of nicotine. METHOD: We searched the literature using PubMed and the search terms ‘schizophrenia’, (‘nicotine’ or ‘smoking’), ‘cognition’ and ‘P50’. RESULTS: Attention and visuo-spatial memory seems to respond favourably to once-only stimulation by nicotine. These results are supported both by the improvement that nicotine brought about in the signal-to-noise ratio in a P50 sensory grating paradigm and by the neurobiological findings. However, the effect of chronic nicotinergic stimulation is less clear. CONCLUSION: There is some evidence that nicotine does have a mild but acute cognition-enhancing effect in patients with schizophrenia. However, nicotine is not suitable for clinical use, because it can have side effects and lead to addiction and desensitisation of the nicotine receptor. Nevertheless, nicotine receptor agonists do have the potential to enhance and stimulate cognition.