Regular use of other stimulants (i.e., crack/cocaine) showed a similar effect on accuracy as
recent and past-year MA use, but processing speed scores were somewhat lower for regular
crack/cocaine users compared to those who did not use crack/cocaine regularly, thus,
significantly lower efficiency scores were observed for regular crack users. Previous studies
indicate cocaine users showed significant impairment in short-term verbal and working
memory, and unlike our findings for MA use, neuropsychological test scores were correlated
with lifetime amount of cocaine used.29,30 A lower learning accuracy score was predicted by
regular use of alcohol to intoxication, however, regular use of other substances
(tranquilizers, heroin) was not associated with cognitive test scores.