HEAVY USE OF MARIJUANA MAY LEAD TO PSYCHOSIS

New Study; Many Adults in the Sample Had None of the Usual Risk Factors

Among individuals who appear to be "mentally well," heavy use of
marijuana may predispose them to develop schizoprehenia and other
"psychoses," new research suggests.

Among 92 patients, ages 18 to 65 years, who suffered a first episode
of functional psychotic illness, more than half said they smoked
marijuana daily or nearly every day and most of these individuals
(66%) had no pre-existing signs of abnormal neurological development
that would put them at risk for psychosis.

They had no family history of psychosis; they had been doing well
academically; they had a group of friends and as such were not
socially isolated; and they had good muscle coordination, Dr. Miguel
Ruiz-Veguilla, of the Institute of Neurosciences of the University of
Granada, Spain, and co-investigators explain in the latest issue of
the journal Schizophrenia Research.

The remaining 43% of the study subjects with a first psychotic
episode did have signs of abnormal neurological development that
increased their risk of psychosis, such as a family history of
psychosis and trouble in the social and academic worlds.

The new and most interesting study finding, wrote the researchers, is
that mentally healthy adults who smoke marijuana daily or nearly
every day may experience psychotic symptoms, while not having any of
the risk factors for these symptoms.

This study, Veguilla further explained, suggests patients with poor
social and academic adjustment before the onset of illness "do not
need an environmental factor in order to develop psychosis."

"While people with good social and academic adjustment before the
onset of psychosis illness -- defined as having more than five
friends; good academic function; good motor coordination and sensory
integration; and no family history of psychosis -- need a strong
environmental factor, such as smoking cannabis every day, to develop psychosis.