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Abstract:
Working memory tasks were given to 17 adults (paid
volunteers) participating in a PET study of methamphetamine abuse.
The methamphetamine abusers (n = 9) reported heavy use of
methamphetamine and no other major drug use; controls (n = 8)
reported no substantial illicit substance abuse. Methamphetamine
users abstained for 5ñ11 days prior to testing. Absolute
regional and global cerebral glucose metabolism (rCMRglc, CMRglc)
were assayed with PET and the [F-18]fluorodeoxyglucose method
during performance of an attentional task. A laterality index for
brain region was assessed by subtracting the absolute rCMRglc of
the right hemisphere from the rCMRglc of the left hemisphere and
dividing this by the sum of the two. Inferior frontal cortex
laterality was significantly correlated with performance on the
digit symbol subtest (r = .688, p = .006) and the missing digit
test (r = .544, p = .044). Good performance was associated with
greater rCMRglc in this brain region. Six of the comparison
subjects, but only one of the methamphetamine abusers had greater
left inferior frontal rCMRglc. These results support involvement of
the left prefrontal cortex in working memory, and differences
between methamphetamine and control participants in the activation
of the inferior frontal cortex during performance of an attentional
task. Supported by: NIH Grants 1 Y01 DA 50038-00 and
1-RR00865
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