New York, Jan 25 (IANS): Nicotine may have a direct impact on the restoration of normal brain activity in people suffering from psychiatric disorders such as schizophrenia -- a disorder affecting 51 million people worldwide, a study has found.

The findings showed that when mice with schizophrenic characteristics were given nicotine daily, their sluggish brain activity increased within two days and within a week it was normalised.

"Since the repeated administration of nicotine restores normal activity to the prefrontal cortex, it could pave the way for a possible therapeutic target for the treatment of schizophrenia," said lead author Uwe Maskos from Integrative Neurobiology of Cholinergic Systems Unit or Institut Pasteur -- a French non-profit private foundation.

It has been observed that schizophrenic patients often use smoking as a form of self-medication to alleviate the deficit symptoms caused by their disorder or to combat the serious side effects of their treatment -- lethargy, lack of motivation, etc.

Patients with schizophrenia -- 80 to 90 per cent of whom are often heavy smokers -- have impairments in the prefrontal cortex -- the brain region associated with cognition, decision-making and working memory.

Recently, the genetic mutation CHRNA5, which encodes a nicotinic receptor subunit, was identified as being associated with the cognitive impairments in schizophrenic patients and with nicotine dependence.

In the new study, scientists introduced the human CHRNA5 gene into mice with the aim of reproducing the cerebral deficits that characterise schizophrenia, namely behavioural deficits in situations of social interaction and while performing sensorimotor tasks.

The results showed that mice with the CHRNA5 mutation had reduced activity in their prefrontal cortex.

The drop in activity measured in this model is similar to that observed in patients with psychiatric disorders such as schizophrenia and addiction, the researchers said.

The study was published online in the journal Nature Medicine.