Nicotine and its association with several mental health disorders including schizophrenia is a widely studied area. The association, however, is not clearly understood. Studies have been carried out to isolate the nicotine metabolites present in both animal and human brains, but particularly in people with schizophrenia.
Cognitive effects
Certain studies have shown that nicotine could help improve the cognitive deficits that schizophrenia can cause. One study showed that nicotine modestly improved spatial memory and attentive ability in schizophrenic patients.
Prepulse inhibition
One study showed that nicotine improves prepulse inhibition (PPI) in schizophrenic patients. PPI involves a prestimulus weakening the reaction to starting stimulus. A deficit in PPI results in an inability to filter out unnecessary information and such deficits have been identified in patients with schizophrenia and Alzheimer's disease. The study of 18 schizophrenic patients and 12 controls showed a significant improvement in PPI among schizophrenic patients, with a greater improvement observed the more clinical symptoms they had.
Hypotheses for smoking in schizophrenia
Smoking is a lot more common among schizophrenics than in the general population, with 80% of schizophrenics taking up the habit compared with 20% of the general population in the US.
Suggested reasons for why schizophrenics tend to smoke include unemployment and inactivity creating a need to relieve boredom; increased levels of neuroticism and anxiety, the stress relief smoking can provide when confronted with negative emotions and stress and improved cognitive ability after smoking. Smoking also reduces the side effects of some of the antipsychotic medications in some schizophrenics.
Further Reading
Cannabis vaping linked to increased use of other substances, study finds