Animal models show that anabolic steroids
flip the adolescent brain's switch for aggression
Anabolic steroids not only make teens more aggressive,
but may keep them that way into young adulthood.
The effect ultimately wears off but there may
be other, lasting consequences for the developing
brain. These findings, published in February's
Behavioral Neuroscience, also showed that aggression
rose and fell in synch with neurotransmitter levels
in the brain's aggression control region.
Behavioral Neuroscience is published by the American
Psychological Association (APA). Neuroscientists
are deeply concerned about rising adolescent abuse
of anabolic-androgenic steroids (AASs), given
the National Institute on Drug Abuse's estimate
that nearly half a million eighth- and 10th-grade
students abuse AASs each year. Not only do steroids
set kids up for heavier use of steroids and other
drugs later in life, but long-term users can suffer
from mood swings, hallucinations and paranoia;
liver damage; high blood pressure; as well as
increased risk of heart disease, stroke and some
types of cancer.
Withdrawal often brings depression, and recent
research suggests that some AASs may even be habit-forming.
Overseen by Richard Melloni Jr., PhD, of Northeastern
University in Boston, the current study of 76
adolescent hamsters compared how individual hamsters
behaved when another hamster was put into their
cages. Normally mild-mannered hamsters still defend
their turf, learning aggression during puberty
by play-fighting, much like humans. Their roughhousing
normally includes wrestling and nibbling - pretty
tame stuff. However, hamsters injected with commonly
used steroids (suspended in oil) became extremely
aggressive. Even after the drug was withdrawn,
the newly vicious hamsters attacked, bit and chased
the intruders. In fact, their aggressiveness measured
ten times greater than that of control hamsters
injected with oil only. Their full-blown aggression
- clearly drug-induced - lasted for nearly two
weeks of withdrawal, the equivalent of half their
adolescence.
Eventually, the aggressiveness subsided; by three
weeks of withdrawal, all the hamsters greeted
intruders with normal, playful defensiveness.
Autopsy revealed that the outward aggressiveness
correlated with inner changes in the brain. When
the drugged hamsters were hostile hosts, a part
of their brains called the anterior hypothalamus
pumped out more of a neurotransmitter called vasopressin.
By three weeks of withdrawal, vasopressin levels
subsided in parallel with the aggressive behavior.
The anterior hypothalamus regulates aggression
and social behavior. Thus, vasopressin - already
known to stimulate that area - appears to fuel
the engine of aggression. And, says Melloni, "Steroids
step on the gas for agression." Thus, the
neuroscientists conclude that the aggressiveness
triggered by anabolic steroids, although reversible,
may last long enough to create serious behavioral
problems for adults. Because this part of the
rodent and human nervous systems are similar,
researchers generalize their findings to humans.
As a result, Melloni and his colleagues speculate
that anabolic steroids can dramatically shorten
teenage fuses (not known for length under the
best of circumstances) and make young people "pop
off" for years, a danger to themselves and
to others. Melloni and others researchers also
are concerned that drug use during a critical
window in brain development can change their wiring
for good.
He says, "Because the developing brain is
more adaptable and pliable, steroids could change
the trajectory if administered during development."
His lab is releasing other new findings, as yet
unpublished, that the serotonin system - implicated
in depression - may never recover. "If you
hit the right areas of the brain at the right
time, you make permanent changes," Melloni
concludes from the converging evidence. He hopes
that adolescents don't take the ultimate recovery
of the vasopressin system to mean it's OK
to use the drugs. "It's our hope that
people considering the use of these drugs weigh
the long-term health risks and the serious potential
for aggression and violence. Muscle mass and medals
aren't worth the risk of hurting someone or
landing in jail.
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