Confirmatory Factor Analysis and Temporal Stability of the Caffeine Expectancy Questionnaire (CaffEQ)
Caffeine is the most widely consumed behaviorally active drug in the world, yet little is known about the expectancies consumers have about its effects. In a series of prior studies, we assessed self-reported expectancies for caffeine among caffeine consumers and non-consumers to identify the nature and scope of caffeine expectancies and to develop a valid and reliable seven factor caffeine expectancy questionnaire (CaffEQ). In the present study the CaffEQ was administered to 665 participants to evaluate the fit of the hypothesized seven factor CaffEQ. Associations between CaffEQ factors and caffeine exposure, frequency of caffeine use, symptoms of substance dependence and caffeine administration vehicle were also accessed. The CaffEQ was readministered to 440 (66.2%) of the original sample approximately two weeks later to assess the temporal stability of the CaffEQ factors. Confirmatory factor analysis confirmed the seven factor solution indicating good model fit and test-retest reliability. The frequency and quantity of caffeine use was associated with greater expectancies for Withdrawal/Dependence, Energy/Work Enhancement, Appetite Suppression, Social/Mood Enhancement, and Physical Performance Enhancement and lower expectancies for Anxiety/Negative Physical Effects and Sleep Disturbance, with the largest effects observed in the Withdrawal/Dependence scale. Caffeine expectancies predicted various features of substance dependence (e.g., use despite harm, withdrawal incidence and severity, perceived difficulty stopping use, tolerance) as well as latency to consume caffeine after waking. Expectancies for caffeine consumed via coffee were stronger than for caffeine consumed via soft drinks. The CaffEQ demonstrates good reliability and construct validity, and should facilitate the advancement of our knowledge of caffeine and drug use in general.