In a study designed to examine the impact of marijuana use on mood and cognitive performance within the context of work and everyday life, Wadsworth and colleagues (2006) administered several neurocognitive measures and ratings of mood to a group of marijuana smokers and age and IQ matched non-smoking control subjects employed full time at the beginning and end of a typical work day in adults, both on Monday and Friday of the week. Measures of mood were derived from a computer administration of a bipolar visual analog scale (i.e. drowsy – alert) and included items categorized into alertness, hedonic tone and anxiety. Relative to the control subjects, the marijuana smokers demonstrated reduced alertness, as well as an effect of day, time and order of the mood testing. In general, marijuana smokers’ generally lower alertness levels were most evident prior to work at the start of the week, and tended to worsen with increased frequency of use. It is of note that despite the finding of reduced alertness in the smokers, which was assessed by self-report, no changes in anxiety ratings
