Tracking difficulties and paranoid ideation during hashish and alcohol intoxication.

In a double-blind study using each subject as his own control, 6 normal subjects smoked 20 mg of THC within 10- and 45-minute periods ("fast" and "slow" conditions, respectively). Each subject also received placebo and doses of alcohol calculated to be as intoxicating as the THC doses. In fast conditions, THC induced greater difficulties with tracking information over time, greater disruptions of self-other interpersonal perceptions, and more persecutory ideation that did alcohol or placebo. Similar but less marked differences were found in the slow conditions. As hypothesized, changes in tracking difficulties, self-other metaperspectives, and persecutory ideation were substantially and significantly correlated.