Mental health and health behaviours in adolescence and risk of being NEET from ages 16 to 24: longitudinal findings from the UKHLS

Background: Young people who are Not in Education, Employment, or Training (NEET) represent a major public health and societal challenge. Existing evidence has linked adolescent mental health problems and health risk behaviours to NEET but has largely treated NEET as a static, rather than longitudinal outcome and overlooked the combined effects of multiple health conditions. Methods: Using data from 5,262 participants born between 1993 and 2000 in the UK Household Longitudinal Study, this study examined the independent and combined associations of adolescent mental health problems (emotional symptoms, conduct problems, hyperactivity) and health risk behaviours (regular smoking, drug use, alcohol use, and high social media use) with ever-NEET status, NEET chronicity, and NEET trajectories from ages 16 to 24, using modified Poisson, proportional odds, and multilevel logistic regression models, respectively. Findings: All mental health problems were associated with ever-NEET status (RRs 1.24-1.27) and NEET chronicity (ORs 1.41-1.98); emotional symptoms showed a widening disadvantage with age, while the disadvantages associated with conduct problems and hyperactivity remained stable. Among health risk behaviours, regular smoking showed the strongest and most persistent relationships with NEET (ever-NEET RR 1.54; chronicity OR 1.64); drug use was related to ever-NEET status (RR 1.37) and an increasing disadvantage after age 21-22, while alcohol use and social media use showed limited associations. NEET risk generally increased with the number of co-occurring conditions, but for recurrent NEET (three or more occasions), risk was only elevated at three or more co-occurring conditions. Interpretation: Adolescent health exposures were associated with NEET risk during ages 16-24, but the strength and pattern varied by exposure and outcome, offering potential insights into the timing and emphasis of any interventions.