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Addiction
to drugs may be a problem people are born with, new research suggests.
Scientists at
Cambridge University carried out studies on rats which indicate that
some individuals are more likely to get hooked on drugs than
others. Changes in brain chemistry have already been linked to
drug addiction. But it has been unclear if they pre-dated exposure to
drugs, or were caused by it. The new evidence suggests that some people
can be programmed for drug addiction by their brain make-up.
Using
a positron emission tomography (PET) brain scan, the team led by Dr Jeff
Dalley found that impulsive rats which had not been exposed to drugs had
fewer dopamine receptors than their more restrained counterparts. These
are molecular sites which respond to the brain chemical dopamine, a key
neurotransmitter that passes messages between nerves. The same
rats were found to be much more likely to self-administer cocaine.
The research, published in the journal Science, demonstrates that
dopamine receptor changes and impulsivity pre-date drug use and do not
emerge as a result of prolonged addiction.
Dr
Dalley said: "The next step is identifying the gene or genes that
cause this diminished supply of brain receptors. This may provide
important new leads in the search for improved therapies for attention
deficit/ hyperactivity disorder (ADHD) and compulsive brain disorders
such as drug addiction and pathological gambling."
An
estimated 281,000 to 506,000 people are addicted to Class A drugs, such
as ecstasy, cocaine and injectable amphetamines, in England and Wales. |
