Methamphetamine Abuse, HIV Infection
Cause Changes in Brain Structure
Alterations May Be Related to Cognitive Deficits
New research published in the August 2005 issue of
the American Journal of Psychiatry indicates
that methamphetamine abuse and HIV infection cause significant
alterations in the size of certain brain structures,
and in both cases the changes may be associated with
impaired cognitive functions, such as difficulties in
learning new information, solving problems, maintaining
attention and quickly processing information. Co-occurring
methamphetamine abuse and HIV infection appears to result
in greater impairment than each condition alone.
“Methamphetamine abuse is linked with HIV, hepatitis
C, and other sexually transmitted diseases, not only
by the use of contaminated injection equipment, but
also due to increased risky sexual behaviors,” says
Dr. Nora D. Volkow, director of the National Institute
on Drug Abuse (NIDA), National Institutes of Health,
which helped support the research. “These findings show
that methamphetamine abuse and HIV infection each cause
significant changes in the volume of brain gray matter
structures and cognitive function.”
Scientists led by Dr. Terry Jernigan of the HIV Neurobehavioral
Research Center of the University of California-San
Diego conducted brain scans to analyze structural volume
changes in 103 adults divided among four populations:
methamphetamine abusers who were HIV-positive; methamphetamine
abusers who were HIV-negative; nonabusers who were HIV-positive;
and nonabusers who were HIV-negative. They also assessed
the ability to think and reason using a detailed battery
of tests that examined speed of information processing,
attention/working memory, learning and delayed recall,
abstraction/executive functioning, verbal fluency, and
motor functioning.
They observed that methamphetamine abuse is associated
with increases in the volume of the brain’s parietal
cortex (which helps people to understand and pay attention
to what’s going on around them) and basal ganglia (linked
to motor function and motivation). HIV infection is
associated with prominent volume losses in the cerebral
cortex (involved in higher thought, reasoning, and memory),
basal ganglia, and hippocampus (involved in memory and
learning).
The scientists stress that among the recent methamphetamine
abusers in the study, the degree of volume increase
in the parietal cortex was associated with worse cognitive
function.
“In HIV-infected people, the cognitive impairments
are associated with decreased employment and vocational
abilities, difficulties with medication management,
impaired driving performance, and problems with general
activities of daily living, such as managing money,” says
Dr. Jernigan. “The impact of methamphetamine on daily
functioning is less well studied, although it is known
that abusers of the drug have impaired decision-making
abilities. These could potentially affect treatment
and relapse prevention efforts, as well as things like
money management and driving performance.”
The brain volume changes associated with methamphetamine
abuse did not correlate with the amount of the drug
a person ingested. However, the study results suggest
that younger methamphetamine abusers showed larger effects
in some brain regions. Among HIV-infected individuals,
the researchers noted a direct association between the
severity of the infection and greater loss of brain
matter.
In methamphetamine abusers who are also HIV-positive,
decreased volumes are correlated with increased cognitive
impairment in one brain region, the hippocampus.
Dr. Jernigan explains that the changes seen in brain
structures could be the result of inflammation in the
brain and/or compensatory changes associated with methamphetamine
toxicity. Also, brain inflammation associated with HIV
infection may contribute to brain cell shrinkage or
loss.
Dr. Volkow says medications that reduce inflammation
might be useful in treating methamphetamine abusers.
“The effects of methamphetamine and HIV on the brain
are distinct but may affect the same brain regions,
so understanding how the underlying mechanisms interact
also may lead to more effective therapies and the information
should be useful in guiding future studies,” Dr. Volkow
concludes.
The National Institute on Drug Abuse is a component
of the National Institutes of Health, U.S. Department
of Health and Human Services. NIDA supports most of
the world’s research on the health aspects of drug
abuse and addiction. The Institute carries out a large
variety of programs to ensure the rapid dissemination
of research information and its implementation in
policy and practice. Fact sheets on the health effects
of drugs of abuse and information on NIDA research
and other activities can be found on the NIDA home
page at http://www.drugabuse.gov/.
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Nation's Medical Research Agency — is comprised
of 27 Institutes and Centers and is a component of
the U. S. Department of Health and Human Services.
It is the primary Federal agency for conducting and
supporting basic, clinical, and translational medical
research, and investigates the causes, treatments,
and cures for both common and rare diseases. For more
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