Exogenous nicotine normalises sensory gating in schizophrenia; therapeutic implications

SummaryThere is a current popular recognition that cigarette smoking is deleterious to health. Although this is very clearly the case for physical health, the situation regarding mental health is, however, rather more complicated. This piece concentrates on the role of smoking in schizophrenia: it is important to consider why schizophrenia, exceptionally amongst the severe and enduring mental illnesses, is associated with increased cigarette consumption. People who suffer from schizophrenia consequently have a greater risk of the complications to physical health caused by this addiction and clearly, it is important to understand why this occurs. Numerous investigators have found that both neuroleptic-naïve, first-onset schizophrenics, together with chronic sufferers of the illness, consume more cigarettes and extract a greater amount of nicotine from them. Researchers have further determined that there is deficient endogenous central nicotinic neurotransmission in schizophrenia, which causes a disruption of sensory gating. This disrupted sensory gating is a reasonable explanation for the delusional misinterpretation of consequent cerebral events. This is the principal reason for the markedly increased rate of cigarette smoking in people with schizophrenia: tobacco cigarette smoking represents an attempt at self-medication in schizophrenia, because the additional nicotine so provided alleviates the hypofunctional sensory gating seen in this illness. Nicotine has been proposed to alleviate negative symptoms. The hypothesis here proposes that as nicotine alleviates positive symptoms, it consequently also – ultimately – prevents negative symptoms caused by the apoptotic effects of excitotoxicity. It would be worthwhile to investigate the therapeutic effects, if any, of additional exogenous nicotine delivered in a less toxic form than cigarettes.