Estimates of Caffeine Use Disorder, Caffeine Withdrawal, Harm and Help-seeking in New Zealand: A cross-sectional survey
Introduction
More than 80% of adults in western countries consume caffeine every day, 122–226 mg per day on average (Verster & Koenig, 2018). Caffeine is a psychoactive drug, found in a wide variety drinks such as coffee, tea, cola and energy drinks, and some supplements, medications and food such as chocolate (European Food Safety Authority, 2015). The recommended upper limit for caffeine intake is 400 mg per day for healthy adults (Nawrot et al., 2003, Wikoff et al., 2017).
Despite its widespread availability, research indicates caffeine may be associated with physical and psychological harm. Potential harms from excessive caffeine consumption include: acute toxicity, cardiovascular toxicity, bone and calcium effects, behavioral effects, impaired fetal development and subfertility; though individual susceptibility to harm is extremely variable (Nawrot et al., 2003, Wikoff et al., 2017). Additionally, and more commonly, harms not necessarily meeting criteria for clinical diagnosis are experienced (Sweeney, Weaver, Vincent, Arria, & Griffiths, 2019). These include stress, headaches, insomnia (Morphett, Heath, McIntosh, & Dorrian, 2014), being bothered by “coffee nerves” (Foxx & Rubinoff, 1979), and feeling addicted (Kromann & Nielsen, 2012). Heavy caffeine intake is positively associated with other addictive behaviors, including smoking persistence (Treur et al., 2016) and increased alcohol consumption and alcohol related harm (Benson et al., 2020, Lau-Barraco et al., 2014). Research also suggests that caffeine can increase impulsivity and poor decision making when gambling (Grant & Chamberlain, 2018).
Abrupt cessation of caffeine consumption following regular use can prompt withdrawal symptoms (Evans and Griffiths, 1999, Juliano and Griffiths, 2004). The DSM-5 includes Caffeine Withdrawal (American Psychiatric Association, 2013), and Caffeine Use Disorder (CUD) is included as a condition for further research. Prevalence estimates for CUD currently lie between 6% and 13.9% (Ágoston et al., 2018, Meredith et al., 2013). People experiencing caffeine-related harm in some cases require treatment to support reduction (Juliano, Evatt, Richards, & Griffiths, 2012), but treatment availability is limited (Meredith et al., 2013). This is due partly to gaps in the caffeine research literature. Those studies that have examined treatment approaches to assist with reducing caffeine consumption suggest that gradual reduction, with or without therapist support, may be effective (Evatt et al., 2016, Sweeney et al., 2019), or psychoeducation on the pros and cons of reducing caffeine intake (Bryant, Dowell, & Fairbrother, 2002). Those who seek treatment appear to consume relatively high amounts of caffeine (>500 mg per day) in the form of coffee or soft drinks (Juliano et al., 2012).
Despite recognition that caffeine may be an addictive substance (and recognized in the DSM), with the potential to cause harm, there are significant research gaps. For example, whilst average consumption levels, and proportions of people in the 95th percentile are frequently reported (Fulgoni et al., 2015, Thomson et al., 2014), the proportion of adults consuming more than 400 mg of caffeine per day is rarely documented. Without this information we do not know the proportion of people at risk of caffeine-related harm. CUD prevalence estimates are also rare. Current estimates are derived from a single review, of which only two very small studies were from the general population (USA and Italy) (Meredith et al., 2013), and a recent, larger non-representative sample from Hungary (Ágoston et al., 2018). Both studies called for estimates from other countries to develop our understanding of CUD, including which socio-demographic groups may be the most affected. Though there is a growing body of research about medical harm from caffeine (Nawrot et al., 2003, Wikoff et al., 2017), research quantifying less severe caffeine related harm, beyond selected mental health outcomes and quality of life measures (Distelberg, Staack, Elsend, & Sabaté, 2017) is not forthcoming.
The aims of this study were to: 1) estimate types and levels of caffeine consumption amongst a convenience sample of adults in New Zealand; 2) estimate CUD and caffeine withdrawal levels according to proposed DSM-5 criteria; 3) describe the range of harms related to caffeine consumption; 4) model the associations between caffeine intake level and sociodemographic characteristics as predictors, and CUD, caffeine withdrawal, and caffeine related harm as outcomes; and 5) examine help-seeking preferences for caffeine reduction.
Section snippets
Survey design and administration
An anonymous cross-sectional survey was delivered online (October 2018) via Qualtrics survey software. A convenience sample was recruited using Facebook advertising over a three-week period. Participant inclusion criteria were being at least 18 years old, living in New Zealand, and being able to read and write English. To facilitate participation, a prize draw for one of six $100 shopping vouchers was offered. The study was approved by University of Auckland Human Participants Ethics Committee
Respondent characteristics
3286 participants consented to take part in the survey. Given the focus of the paper, we excluded participants who did not complete the following measurement tools: caffeine consumption (n = 109), CUD (n = 393), caffeine withdrawal (n = 8) and caffeine related harm (n = 392). A total of n = 2379 respondents (72.4% of the initial sample) were included for analysis. As shown in Table 1, respondents were relatively young (median = 21, range 18–74) and nearly two-thirds of the sample were female.
Missing data
As
Discussion
This study aimed to estimate levels of caffeine consumption amongst adults in New Zealand and their associations with CUD and caffeine withdrawal, after including a range of sociodemographic variables. It also aimed to explore caffeine-related harm, and preferred treatments should help be sought. This study found that in a convenience sample recruited via Facebook advertising, one in five people in New Zealand consumed more than 400 mg of caffeine per day. Levels of caffeine consumption and
Funding sources
Data collection was funded by the School of Population Health, University of Auckland. Manuscript preparation was funded by the Health Research Council New Zealand. The University of Auckland and the Health Research Council had no role in the study design, data collection, preparation of this manuscript or the decision to submit the article for publication.
Contributions
S.N. Rodda designed the study and sought the funding. N. Booth conducted literature searches and prepared the first draft of the manuscript. N. Booth, J. Saxton conducted the statistical analysis. All authors contributed to and have approved the final manuscript.
Ethical approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Conflict of interest
The authors have no competing interests to declare in relation to this article.
CRediT authorship contribution statement
S Rodda conceived the study, acquired funding, provided supervision and reviewed and edited the manuscript. N Booth was responsible for data curation, formal analysis, project administration and writing the original draft. J Saxton assisted with supervision, writing review and editing and oversight of formal analysis.
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