SLOW DOWN

Speed Has Damaging Effects On The Brain That May Linger For Months

DRUG abusers hooked on "speed" risk brain damage, even months after
they quit. A new study shows that methamphetamine is more toxic to the
brain than heroin, cocaine or alcohol, and could put people at high
risk for neurodegenerative diseases such as Parkinson's.

Methamphetamine is an addictive drug that boost levels of dopamine, a
neurotransmitter that stimulates brain cells, enhancing mood and
making people more animated. But previous studies of animals given
speed have suggested that the drug also sabotages the dopamine system,
reducing levels of molecules called dopamine transporters that shuttle
the feel-good neurotransmitter around the brain. "Those studies in
animals were very dramatic-we needed to know whether the same thing
happens in humans," says Nora Volkow, a psychiatrist at Brookhaven
National Laboratory in New York state.

To find out, Volkow's team recruited 15 methamphetamine addicts who
had abused speed for at least two years, then stayed off the drug for
at least two weeks. The scientists carried out positron emission
tomography (PET) scans to measure levels of dopamine transporters in
the brains of the former addicts and 18 volunteers who had never taken
speed.

Levels of dopamine transporters in the former drug abusers-even those
who had been clean for almost a year-were more than 20 per cent lower
than normal in two key areas of the brain involved in movement,
concentration and motivation. This reduction mimics the effects of
ageing: levels of dopamine transporters naturally fall by between 5
and 6 per cent each decade, causing people to slow down and impairing
their movement and memory. "What we see is the equivalent of 40 to 50
years' ageing in the brains of these people-that's a huge amount,"
says Volkow.

Not surprisingly, the former drug abusers also had impaired movement
and found it difficult to remember lists of words given to them by the
researchers when compared with 18 people who had never taken speed.
Volkow warns that if the damage doesn't reverse itself speed addicts
might be prone to Parkinson's disease, in which levels of dopamine
transporters are hugely depleted.

Volkow and her team also measured the uptake of glucose in the
volunteers' brains, a measure of brain activity. They found that the
rate was around 14 per cent higher in the speed addicts than in people
who had never taken the drug. This unusually high activity can follow
brain damage from injuries or radiation exposure and may reflect
inflammation of the brain.

Volkow concludes that speed could cause long-term damage to the
dopamine system. "In that respect, speed is much more dam- aging than
cocaine or alcohol," she says. Her team plans to monitor the former
addicts over several years to find out if the damage is permanent.

More at - The American Journal of Psychiatry (vol 158, p 377 and p 3831)