Acute effects on central nervous system functions and behaviour. The acute effects of cannabis use have been recognized for many years, and features such as mild euphoria, relaxation, increased sociability, heightened sensory perception and increased appetite have been described in earlier reports. The acute effects of higher doses, including perceptual changes, depersonalization and panic have also been well described previously (ARF/WHO, 1981). Research conducted since the last WHO report has focused mainly on quantifiable effects such as those on memory, psychomotor performance and appetite; however, some work has also been done on the acute psychotropic effects of cannabis. A recent report done by Mathew et at. (1993), showed that cannabis smoking was associated with significant depersonalization that was maximal 30 minutes after smoking. Other behavioural changes associated with cannabis intoxication included loss of time sense, sensation of high, anxiety, tension and confusion.   (Mathew et al 1993).

Several studies have shown that cannabis appears to increase the perceived rate of the passage of time. Consistent with earlier observations, numerous studies in the past ten years have confirmed that cannabis impairs psychomotor performance in a wide variety of tasks, such as handwriting, tests of motor coordination, divided-attention, digit-symbol substitution, and operant tasks of various types (Solowij et at., 1991). The consistency of results is probably attributable to improved experimental technique, as reflected by greater attention to the importance of task complexity, standardization of THC administration. studies of dose-effect relationships, and of sharper definition of acute versus residual effects.