Illegal drug use is one of the main contributors to the global burden of disease (1) that has adverse health and psychological consequences (2). The overall prevalence of illegal drug use in 2018–2019 ranges from 5.9 to 12% in the United Kingdom. However, this number was particularly high for young people, which ranges from 21 to 28% (3). Moreover, according to Allen and Laborde (2), “Illicit drug use and dependence are associated with an increased risk of mental disorders, road-traffic accidents, fatal overdoses, infections from unsafe injection practices (e.g., contraction of HIV), suicide and violence (1, 4), and illicit drug dependence accounted for 20 million (95% UI: 15.3, 25.4 million) disability-adjusted life years (DALYs) worldwide in 2010 (4).” Given the negative consequences associated with illegal drug use, there has been progress in trying to identify factors that relate to illegal drug use (2), including individual, interpersonal, community, and policy factors as pointed out by the social-ecological model. For instance, poor mental health, peer pressure, deprived family environment are factors of illegal drug use (5), which are also related to life satisfaction and SRH.

Self-rated health (SHR) refers to the subjective evaluation of one’s overall health whereas life satisfaction refers to how a person likes his or her life (6). It has been suggested that drug use is negatively related to life satisfaction (7). For instance, Zullig et al. (7) found that drug use is negatively related to SRH in American high school students. Boyas et al. (8) found that drug use is negatively related to SRH between Latino and non-Hispanic white adolescents aged between 12–17 in the United States. Moschion and Powdthavee (9) found that cannabis use is negatively associated with life satisfaction and the decrease in life satisfaction following the use of drugs persists 6 months to a year after initial use in homeless or at risk of being homeless participants in Australia. Illegal drug use may relate to life satisfaction and SRH through pathways such as poor physical and mental health (5), deprived socioeconomic status (10), and social stigma (11).

Thus, although there are some studies about how drug use is related to SHR and life satisfaction in young and middle adolescence [aged below 17; e.g., (7, 8)] and adults [e.g., (12)], much less is known about how drug use is associated with life satisfaction in young people in late adolescence and emerging adulthood, particularly in the United Kingdom. In late adolescence and emerging adulthood, individuals have to achieve autonomy from their guardians and will experience shifts in social roles and some normative expectations for their own behaviors. In this period of time, young people explore various aspects of their life including education, work, leisure interests, romance, and worldviews. The lifestyle factors associated with this period appear conducive to facilitating the development of addictions such as drugs [see (13) and (14) for reviews]. Moreover, newly found autonomy can lead to various mental health problems such as stress, anxiety, and depression, which in turn contribute to illegal drug use (15).

Thus, the aim of the current study is to investigate how illegal drug use is related to life satisfaction and SRH in young adults in the United Kingdom while controlling for demographics and other substance use behavior. The current study hypothesizes that drug use is negatively related to both life satisfaction and SRH.

Descriptive statistics can be found in Table 1. The overall prevalence of illegal drug use was 18.89%. Young people who used illegal drugs during the past year received less college-level education, tended to live in a rural area, were more likely to consume alcohol during the past year, and were more likely to be a smoker and have used e-cigarettes than people who did not use illegal drugs during the past year.

The current study found that there is a main effect of age [F(1,2164) = 5.09, p < 0.05], sex [F(1,2164) = 6.10, p < 0.05], and smoking status [F(1,2164) = 5.05, p < 0.05] on life satisfaction among people who did not use illegal drugs in the past year. However, the main effect of monthly income, highest educational qualification, residence, drinking status, and vaping status was not significant.

Moreover, there was a main effect of sex [F(1,2164) = 40.66, p < 0.001], residence [F(1,2164) = 11.05, p < 0.001], smoking status [F(1,2164) = 19.80, p < 0.001], and vaping status [F(1, 2164) = 8.86, p < 0.01] on SRH among people who did not use illegal drugs the past year. However, the main effect of age, monthly income, highest educational qualification, and drinking status on SRH was not significant. The parameter estimates of these general linear models can be found in Table 2.

The current study found that illegal drug use is negatively associated with life satisfaction (t(505) = −5.95, p < 0.001, 95% CI [−0.58, −0.21], Cohen’s d = −0.26) but not with SRH. The mean and standard deviation of predicted scores and actual scores for people who used illegal drugs in the past year were plotted in Figure 1.

The aim of the current study was to identify the relationship between illegal drug use and life satisfaction and SRH. By using a train-and-test approach and a t-test to analyze data from Understanding Society, the current study found that illegal drug use is negatively associated with life satisfaction but not SRH, which is largely consistent with the established literature regarding the association between substance use and poorer life satisfaction and SRH [e.g., (8, 12)]. Illegal drug use can bring not only negative consequences to physical but also psychological health. However, the current study did not find a relationship between drug use and SRH in young people, which may be explained by the fact that the current study controlled for other addictive behaviors including smoking, drinking, and vaping, which has been shown to be associated with poorer SRH [e.g., (7, 8)].

Risky behaviors in young people tend to cluster (20–23). Indeed, newly found autonomy in late adolescence and early adulthood can be a stressful time. In addition, this group of people is known to be less risk-aversive due to the perceptions of invincibility, which then leads to greater experimentation. Additionally, the underlying brain structures are not fully matured yet such as the inhibitory control network [see (24) for a review], which then leads to a higher chance of risky behavior. In addition, other factors such as uncertainty about the future, trauma, and mental health, may contribute to risky behavior such as illegal drug use, and poor life satisfaction.

It is reasonable to think that dissatisfaction with life among young people can be associated with other behaviors that are at risk such as sexual risk-taking, violence, aggression, suicide ideation, and dieting behaviors (7). Behavioral health specialists have begun to focus on the promotion of developmental assets in young people, including psychological wellbeing and adaptation (25–27), which broadens the scope of assessment in young people beyond traditionally assessed risk behaviors and psychiatric symptoms (23, 28, 29). Thus, these approaches may be sensitive to subtle, but clinically meaningful, changes in adolescent cognitive wellbeing. Life satisfaction measures can also extend the score of the wellbeing indicators in other large scale national survey in the United Kingdom.

Despite the strength of this study including well-controlled socioeconomic status and co-use of other substances including alcohol, cigarettes, and e-cigarette, there are some limitations. First, the current study is cross-sectional, which does not give support to strong causal inferences. Future studies should employ longitudinal approaches in order to establish causal association between illegal drug use and life satisfaction and SRH. Second, the current study is based on self-report measures, which can cause bias. Future studies should use more objective measurements to avoid these biases. Third, the type of illegal drug that participants used was not assessed. Future studies should investigate the various effects that different drugs may have on life satisfaction and SHR. Finally, illegal drug use is typically accompanied by psychiatric comorbidities and substance use disorders [e.g., (30, 31)]. However, they were not controlled in the model. Future studies should collect this information and control it to rule out their possible effects on life satisfaction and SRH.

To conclude, the current study investigated how life satisfaction and SRH are affected by illegal drug use status. By using an innovative train-and-test approach, the results showed that only life satisfaction but not SRH is affected by drug use status. There are also some implications that can be drawn from the current study. Interventions that help people quit illegal drug use and campaigns that prevent people from using illegal drugs are largely needed. Findings from the current study should also be utilized as a fact for educational purposes. Moreover, special attention may need to be given to young people who are at the stage of achieving autonomy, and who are at a higher risk of illegal drug use. For instance, providing consulting services at schools may provide a better chance for young people to successfully achieve autonomy and overcome difficulties in this period of time, which may reduce illegal drug use and promote life satisfaction.

Publicly available datasets were analyzed in this study. This data can be found here: https://www.understandingsociety.ac.uk.

The studies involving human participants were reviewed and approved by the University of Essex. The patients/participants provided their written informed consent to participate in this study.

WK: conceptualization, data curation, formal analysis, investigation, methodology, resources, software, writing—original draft, and writing—review and editing.