WE READ WITH interest the report by Shih-Ku Lin et al. (February 2010 issue) and feel that two points warrant comment.1 First, the authors conclude that there was ‘deterioration’ in the IQ of the methamphetamine users. In order to make such a statement, one must conduct an experimental manipulation that demonstrates a decrease in IQ over time. The current study employed a cross-sectional design, which precludes such a manipulation. As such, language suggesting deterioration in the IQ of methamphetamine users should be considerably tempered. A second concern is that the significance of the demographic information estimation formula index developed by Barona et al. is unclear.2 There are no data on the validity of using this test to estimate the pre-morbid IQ of methamphetamine abusers. Nevertheless, the current results contribute to an important database and appropriately stated caveats will increase the likelihood of a more comprehensive understanding of methamphetamine-related problems.


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