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Release: April 5, 1999

Study focuses on effects of chronic marijuana use on brain function and cognition

IOWA CITY, Iowa -- Robert I. Block, Ph.D., associate professor in the department of anesthesia at the University of Iowa College of Medicine, is looking for subjects to complete his ongoing study on chronic marijuana use, brain function and cognition.

The study, begun in March 1997, with colleagues from the UI departments of radiology, psychology, psychiatry and social work, is using magnetic resonance imaging (MRI) and positron emission tomography (PET) scans to monitor a hypothesized decrease in blood flow through areas of the brain relevant to cognition.

"The main emphasis is on the PET tests," Block said. "During several tests of memory and attention, we will look at the areas we know to be active to see if there is less blood flow among marijuana users."

Block, who has been at the UI since 1984, has performed numerous studies on marijuana and its effects on cognitive ability.

Acute effects of the drug include memory impairment, and it is possible that such difficulties would persist due to heavy use, according to Block. "The idea is that the effects may be long-lasting, but it's premature to say there are actual changes in long-term or permanent brain function associated with chronic marijuana use," he said.

Those interested in participating in the study within the Iowa City area can call for information at (319) 353-6434. Those closer to the Des Moines area, call (515) 246-6585.