Hallucinations nicotinic receptors

Memantine is the first in a novel class of Alzheimer s disease medications acting a.o. on the NMDA receptor of the glutamatergic system. It also acts as an uncompetitive antagonist at different neuronal nicotinic receptors at potencies possibly similar to the NMDA receptor. Memantine is approved for treatment of moderate to severe Alzheimer s disease and its use is associated with a moderate decrease in clinical deterioration of the disease. Common adverse drug reactions (>1% of patients) include confusion, dizziness, drowsiness, headache, insomnia, agitation, and/or hallucinations. 

As well as hallucinations and delusions, schizophrenia is characterized by deficits in information processing. Schizophrenics have difficulty suppressing irrelevant environmental stimuli. This is referred to as sensory gating or prepulse inhibition, and commonly measured with auditory evoked potentials. When two stimuli, such as sounds, are presented within 30-500 msec, the response to the second stimulus rapidly decreases upon repeated presentations in healthy people, but not in persons with schizophrenia (Braff et al., 2001). This deficit is found in family members of patients with schizophrenia, and has been linked to the alpha-7 nicotinic receptor gene. The deficit is reversed by nicotine on an acute basis, and by some antipsychotic drugs. Alpha-7 nicotinic agonists are under development as treatment for schizophrenia (Martin et al., 2004). 

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