use. Another line of research that awaits evaluation
is the comparison of cognitive performance
of MAP patients by country, which would provide
information about cultural, educational, and ethnic
differences and their potential infl uences on MAP
etiology, prognoses, and treatment. Assessment
of the relationship and the potential progression
of cognitive decline with duration of methamphetamine
use and emergence of MAP symptoms
warrant future study. Limitations. When interpreting
these data one should take into account that this
study was limited because of its cross-sectional
design. While this prohibited evaluation of cognitive
functioning prior to the onset of MAP symptoms,
future analyses will assess a subset of MAP participants
who completed repeated neurocognitive
testing over several years. A second limitation
is the lack of objective verifi cation of sustained
abstinence over the course of the follow-up
timeframe. This may be a minor factor however,
as all participants provided urine negative for
methamphetamine at the time of testing, implying
no use in at least a few days. The lack of Thai
norms made it impossible to calculate statistical
signifi cance of the cognitive impairment.
Conclusion
This descriptive study characterizes the
neuropsychological performance of individuals with
methamphetamine-induced psychosis. Continuing to
investigate cognitive performance in MAP patients
in Thailand and in other countries will provide a
better understanding of the etiology and consequences
of MAP. Additionally, neuropsychological
testing may be a valid diagnostic tool to distinguish
methamphetamine abuse from methamphetamineinduced
psychosis, or to inform clinicians trying
to treat individuals with MAP.
Acknowledgments
Support for this research provided by
the National Institute on Drug Abuse grant # U01
DA017394.