New Clue About Cocaine's Brain Effects
Discovery Could Shed New Light on Addiction and Other Brain Diseases
Oct. 11, 2005 -- Cocaine may affect a part of the brain that wasn't
previously recognized as a player in addiction, researchers report.
Their findings may partly explain cocaine's addictive pull. It might also
have meaning for other brain conditions related to dopamine activity such as
Parkinson's disease, the researchers write.
The report comes from researchers including Carl Anderson, PhD, of Harvard
Medical School and McLean Hospital in Belmont, Mass.
The report appears in Neuropsychopharmacology.
Fresh Look at Old Data
Anderson's team dusted off a small study from 1998 comparing 10 people who
used crack cocaine regularly for six or more months and eight other people with
no history of drug addictions.
Participants watched two videotapes: one of butterflies, and one of people
using crack cocaine. Meanwhile, they got brain scans using functional magnetic
resonance imaging (fMRI).
Special attention was paid to the brain's cerebellum, which handles balance
and complex actions like walking and talking. The cerebellum is found at the
back of the brain, tucked under the much larger cerebrum.
When the study was done in 1998, the researchers looked at the entire
cerebellum and didn't see any major differences between the two groups.
Anderson's team re-examined the findings with a closer look. They focused on
a part of the cerebellum called the cerebellum vermis.
The cerebellum vermis was especially active when addicts viewed the crack
cocaine videotape, the researchers report.
Brain Chemical Clue
Next, the scientists turned their attention to dopamine, a brain chemical
which coordinates movement and is stimulated with the use of cocaine.
Their big question: Does the cerebellum vermis have anything to do with
Dopamine is important in several brain conditions. For instance, dopamine
production falters in people with Parkinson's disease.
The cerebellum had been thought to be largely out of the picture with
regards to dopamine, according to the researchers. They note "relatively
low concentrations of dopamine and dopamine receptors" in the cerebellum as
The cerebellum vermis may be involved in the brain's dopamine system, the
That's based on their review of past research, which included PET (positron
emission tomography) brain scans of 11 healthy people.
"Scientists previously contended that the vermis had little involvement
in addiction or other disorders involving dopamine," says Anderson, in a
news release. "This changes the perspective on how brain regions may
interact during addiction. It introduces an entirely new player."
Anderson's colleagues included Luis Maas, MD, PhD, who had worked on the
original videotaped study.