Fuzzy thinking in dope-heads

The journal Neurology reports:

Neuropsychological deficits in long-term frequent cannabis users

The authors examined neuropsychological functioning in 20 long-term (LT), 20 shorter term (ST) heavy frequent cannabis users, and 24 controls after abstinence for ?24 hours prior to testing. LT users performed significantly worse on verbal memory and psychomotor speed. LT and ST users had a higher proportion of deficits on verbal fluency, verbal memory, attention, and psychomotor speed. Specific cognitive domains appear to deteriorate with increasing years of heavy frequent cannabis use.

The sample is small, but this just confirms that marijuana stays in the system for over 24 hours.