Faulty sense of smell found in early schizophrenia cases

A new study has found that a faulty sense of smell may predict precisely the risk of schizophrenia, months or years before obvious symptoms appear.

Until now, doctors have had no reliable way to make an early diagnosis of the debilitating mental illness, which afflicts more than 2 million Americans.

“This is the first time we’ve found a potential marker specifically for schizophrenia. It’s a promising diagnostic tool,” said University of Melbourne neuropsychologist Warrick Brewer, one of the study’s co-authors.

Early detection of schizophrenia can be key, Brewer said, because schizophrenic patients who get prompt treatment generally do better in the long run. A psychotic episode can cause permanent brain damage, increasing the chance of subsequent attacks. Catching the illness early might reduce later problems.

Published in The American Journal of Psychiatry, the study examined 81 people at high risk for developing schizophrenia. The subjects had all shown early subtle signs of the disease: genetic risk, disorganized thinking, or subtle hallucinations or delusions.

Brewer and his colleagues gave this group a standard 40-item scratch-and-sniff test, which asks subjects to smell an odor and then identify it. The smells included bubble gum, gasoline, lemon and licorice.

Twelve of the 81 subjects scored very low on the smell test. Over the next two years, only those 12 developed schizophrenia. Ten other patients also had psychotic episodes, but their symptoms were caused by mental illnesses other than schizophrenia.

Schizophrenia researchers praised the study.