Caffeine is a psychoactive substance which is consumed by people from all over the world, mostly in the form of coffee and tea. However, the popularity of caffeinated soft drinks and energy drinks is also emerging.
Although our knowledge of the effects of caffeine on physical health is expanding, scientists have begun to focus on the addictive potential of caffeine mostly in the last decades. Caffeine withdrawal was included as a diagnostic category in the latest version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), while caffeine use disorder (CUD) was recognized as a “condition for further study.” This is because we do not know enough about its clinical significance.
Taking this into consideration, we compiled a 10-item questionnaire based on the recommendation of the DSM-5 for the assessment of CUD. The Caffeine Use Disorder Questionnaire (CUDQ) contains all those symptoms which are considered to be important characteristics of CUD: craving, tolerance, unsuccessful quitting attempts, caffeine use despite negative consequences, attempts to avoid withdrawal symptoms, longer or more consumption than intended, failure to fulfill obligations because of caffeine use/withdrawal, permanent or recurrent social problems because of caffeine use/withdrawal and a significant amount of time spent with consuming or obtaining caffeine. The last item aimed to assess whether these symptoms caused significant inconvenience or suffering for the caffeine consumer.
We asked 2,259 Hungarian adults about their caffeine consumption habits, and they also completed the newly developed Caffeine Use Disorder Questionnaire in an online, cross-sectional study.
We found that CUD is a unidimensional construct, which means that there is only one caffeine addiction/caffeine use disorder continuum, and there is no need to take into account caffeine dependence and caffeine abuse separately (which is in line with the innovative approach of DSM-5 which ended the categories of “substance dependence” and “substance abuse”).
Although we do not have any cut-off score for caffeine use disorder yet, which would strictly differentiate between people with or without CUD, we could examine which symptoms are more severe and which have higher discriminative value. Severity or difficulty means that if the item has higher threshold then it is endorsed less frequently which means that it is a more “severe” symptom. Higher discriminative value means that the item has the ability to discriminate people higher on the CUD continuum from those lower on the continuum (in other words, people with lower CUD have a much smaller chance of experiencing the symptom than persons of higher CUD).
According to our results, one of the most important aspects of caffeine use disorder is suffering from the symptoms, which was the most capable in discriminating people with lower and higher level of caffeine use disorder, and it was also the third most severe criterion. The two most severe symptoms were failure to fulfill obligations (e. g. work, school or home responsibilities) and social/interpersonal problems because of caffeine consumption; these symptoms mostly occurred on the higher end of caffeine use disorder continuum. This means that although caffeine consumption is a socially acceptable habit, caffeine use can interfere with social or occupational functioning for some individuals.
In contrast, the significant amount of time spent with consuming or obtaining caffeine was the least discriminating criterion, which means that the probability of a positive response at lower levels is nearly the same as it is at higher levels. This low level of discriminative value can be the consequence of the high and legal availability of caffeine compared to other substances. The presence of consumption of more caffeine or longer than intended and craving were likely even in case of lower levels of CUD, therefore, these are considered to be less severe symptoms and do not indicate problematic caffeine consumption. Tolerance (which means that the user have to consume more caffeine to reach the same effect or the same dosage cannot induce the same effect anymore), unsuccessful quitting attempts, caffeine use despite negative consequences and attempts to avoid withdrawal symptoms were moderately severe symptoms and had moderate discriminative values.
Total daily caffeine consumption and also daily coffee, energy drink, and cola intake were related to a higher level of CUD, while daily tea consumption was associated with less CUD symptoms. These results emphasized that we should differentiate between certain caffeinated beverages when we examine possible caffeine-related problems such as caffeine use disorder.
Taken together, the recommended caffeine use disorder criteria have sufficient ability to discriminate people with lower and higher level of caffeine use disorder, and the items of CUDQ properly cover the continuum from the milder to the more severe ends of the spectrum. The applied item response theory (IRT) approach allowed us to ascertain the importance of each item. Since the DSM-5 recognized caffeine use disorder as a possible mental disorder, it is especially important to test the diagnostic criteria in order to avoid false positives and to target those people who really struggle with problematic caffeine consumption (in this study, 8.6% of the participants indicated that they suffer from the symptoms and they may need more evaluation and possibly some assistance for their problems as well).
Although this sample was not representative for the Hungarian population (there were a higher proportion of males, inhabitants of the capital city and participants with higher educational attainment in the sample), this was the first attempt to test the caffeine use disorder criteria recommended by the DSM-5 in a larger sample. The next step should be a more clinically oriented examination of people with possible caffeine use disorder. This could answer some questions about the qualitative properties of the items, for example, what kind of social conflicts can emerge from excessive caffeine use.
These findings are described in the article entitled Caffeine Use Disorder: An item-response theory analysis of proposed DSM-5 criteria, recently published in the journal Addictive Behaviors. This work was conducted by Csilla Ágoston, Róbert Urbán, Mara J. Richman, and Zsolt Demetrovics from ELTE Eötvös Loránd University.