This is an umbrella review, which means it combined many earlier reviews instead of studying people directly. It pulled together 22 meta-analyses that covered 544 primary studies and 76 different conditions, using data from more than 234 million people in 36 countries across six continents. The people studied included both children and adolescents and adults.
The review found that ADHD was linked to a wide range of mental, physical, and behavioral conditions. How strong the evidence was varied from condition to condition. For 12 conditions the evidence was rated as high certainty. These included bipolar disorders, personality disorders, schizophrenia, weaker everyday language skills, night awakenings, obesity, early tooth decay, asthma, astigmatism, farsightedness, crossed eyes (strabismus), and thoughts of suicide. If you are having thoughts of suicide, call or text 988 to reach the Suicide & Crisis Lifeline, any time.
Each link was reported as how much more likely a condition was. People with ADHD were far more likely to have bipolar disorders (odds ratio 5.88 [3.71-9.34]). They were also more likely to have schizophrenia (4.66 [4.09-5.30]) and obesity (1.55 [1.28-1.87]). Completed suicide was more common (6.69 [2.18-20.55]), as was death from any cause (2.13 [1.16-3.89]). These are group-level comparisons across large populations, not a prediction about any one person. If you are having thoughts of suicide, call or text 988 to reach the Suicide & Crisis Lifeline, any time.
The authors noted limits. The studies mixed two age groups, which may explain some of the disagreement between them. Few studies separated ADHD subtypes. Many links came from single-time-point data, so it is hard to say what came first.
Source: Kang J, Lee H, Kim S, et al.. Comorbid health conditions in people with attention-deficit/hyperactivity disorders: An umbrella review of systematic reviews and meta-analyses. Asian Journal of Psychiatry (2024). doi:10.1016/j.ajp.2024.104135