ADHD and Later Health Problems: Finnish Cohort Data

For someone diagnosed with ADHD in childhood, which health problems are more likely in the years that follow? A birth cohort study from Finland asks this by following the nationwide health records of children born in a single year up to the age of thirty-three. The answer has two parts. The risk appears to be raised for mental and neurological diagnoses, while for physical illnesses the authors did not catch an increase. To see how solid the numbers behind this sentence are, you have to look at the details.

Who the study comes from and where

This post is a Turkish-language summary of the paper published open access in Molecular Psychiatry. The paper was published under the Creative Commons Attribution 4.0 (CC BY 4.0) license; the findings belong to the authors of the paper, and the account and appraisal here are mine.

The authors of the paper are G. David Batty, Mika Gissler, Seyed Ehsan Mousavi, Varun Warrier, Tamsin Ford and Markus Keski-Säntti. The study was published in July 2026 and appears in issue 11 of volume 31 of the journal. It is not an experiment but an observational cohort study: nobody was made to do anything; officially collected routine health records were linked to each other. Those followed were born in 1987, so by the end of the study they are at most thirty-three.

A note: I prepared this post not from the full text of the paper but from the abstract the authors wrote. Every number below comes from that abstract.

How it was done

The basis of the study is the 1987 Finnish Birth Cohort. There are 52,594 children born in a single year with complete data, 25,463 of them girls. The ADHD diagnosis was taken from hospital inpatient and outpatient records up to the age of eighteen. That is, by this study's definition, being "someone with ADHD in childhood or adolescence" means carrying an ADHD diagnosis in a hospital record before the age of eighteen. By this criterion, 0.43 percent of the children, that is 228 people, were counted as having ADHD.

This proportion is small. The figures often cited for how common ADHD is in children are quite a bit above it. The abstract does not discuss the reason for the difference, and I will not speculate. I can only say this: the study counts diagnoses that entered a hospital record; diagnoses outside hospital records and diagnoses never made are not in the ADHD group.

A comparison was made with "population controls" without ADHD, and other health problems were followed from the same records up to 2020. The authors used a "phenotype-wide" approach: instead of focusing on a single disease, they looked collectively at a list of diseases and injuries and searched for which showed a difference. According to the abstract, there are 17 health outcomes on the list.

What was found

In the ADHD group, compared with the comparison group, the risk came out higher in all 17 outcomes examined. But at this point we are talking only about direction. "Higher" does not tell apart whether the difference is real or a chance fluctuation. Statistical significance does that.

When age and sex were taken into account, eleven of the 17 outcomes remained statistically significant. Then the authors tightened the sieve: birth weight, the family's socioeconomic situation and the child's school performance were also taken into account, and on top of that a correction for multiple testing was made. After this strict screening, five outcomes remained standing:

Outcome	Odds ratio	Confidence interval (99.7%)
Neurotic disorders	2.11	1.25-3.41
Substance use disorder	2.26	1.27-3.79
Poisoning	2.30	1.02-4.52
Mood disorders	2.45	1.49-3.88
Epilepsy	4.55	1.82-9.55

The authors also filled in the missing data with a statistical method (imputation) and repeated the analysis with 54,045 people. The same associations came out again, and psychotic disorders were added to them: odds ratio 2.63, interval 1.34-5.18. The abstract's overall conclusion sentence is this: in this cohort, young people with ADHD went on to experience an increased burden of mental and neurological illness later, and apparently not of physical illness.

What odds ratio and confidence interval mean

An odds ratio says how many times higher the odds of an event (the probability of it happening divided by the probability of it not happening) are in the ADHD group than in the comparison group. A value of 1 means "no difference". For mood disorders, 2.45 means that the odds of this diagnosis in the ADHD group are about two and a half times higher. If the event is not very common, it would not be too wrong to read it as "about how many times more often". But this number alone does not give how many people it actually occurs in, and the abstract does not write these absolute proportions.

A confidence interval shows how precise an estimate is. Here a 99.7 percent interval was used, that is, more cautious than the usual 95 percent interval. The reason is the correction for multiple testing: when many associations are looked at at once, the chance of finding a result that turns out "significant" by chance rises, and the interval is widened to balance this. If the interval does not include 1, the association is counted as significant.

Looking at the table with this eye, two things stand out. For poisoning, the lower end of the interval is 1.02, that is, it almost touches 1; this result is just above the threshold. For epilepsy, the estimate of 4.55 is the largest number, but the interval runs from 1.82 to 9.55. That says the true value could extend from a little under twice to close to ten times. This width is most likely related to the ADHD group being small: the group is 228 people and epilepsy is a rare diagnosis, and as the number of events falls, the uncertainty grows. I would not interpret this result on its own.

What is said about physical illnesses

The abstract says that the future burden of young people with ADHD "apparently" does not include physical illnesses. This sentence needs to be read closely. In all 17 outcomes examined, the estimate was in the "higher" direction. Of the five that remained standing after strict adjustment, two are directly mental (neurotic and mood disorders), one is substance use, one is neurological (epilepsy), and one is poisoning. Poisoning in the list is neither a mental nor a physical illness in the classical sense; it is a type of injury. The abstract does not open up the reason behind this.

The abstract also does not say which the twelve eliminated outcomes are. There is a fine distinction here: "the risk of physical illness does not rise" and "in this sample, under this strict screening, no evidence came out" are not the same thing. With a group of 228 people it is hard to catch a difference in a disease that is seen rarely anyway. An outcome being eliminated may not show that there is no real difference; it may come from a lack of power. The word "apparently" in the authors' wording carries this caution too.

What this finding means for me

First let me state my own situation: I received my diagnosis at 22, while this study counts diagnoses that entered a hospital record before eighteen. By the study's definition I would not be in the ADHD group. Still, this limit needs to be kept in mind while reading the results, because the group the study calls "with ADHD" is limited to children and young people with a hospital record.

The most striking side of the finding is mood and anxiety. I took up the co-occurrence of ADHD with depression and anxiety separately in the articles ADHD and depression and ADHD and anxiety. For substance use there is the article why alcohol is risky in ADHD. This study can be read as evidence supporting those topics with data from another country.

The practical side is this: when a child or young person with ADHD goes for a check-up, let what is talked about not be only attention, school and behavior. Let mood, anxiety, sleep and substance use be asked about too. In my view these numbers work not as a list of fears but as a list of "where else to look". Looking early for co-occurring mental health conditions in treatment plans is not a conclusion the finding draws directly, but it is a reasonable inference. What each treatment does is the subject of the discussion in the article medication or therapy in ADHD, not of this study.

What the study does not say

There are a few concrete limits.

This is an observational study, so it does not prove causation. The abstract does not say whether ADHD itself, the life circumstances that accompany ADHD (difficulties at school, stress in the family), or shared factors affecting both created these differences. By writing "if any" in the abstract, the authors leave the question open. Let me add a small comment here: since school performance is something that is affected by ADHD and can also affect later health, taking it into account may have made the findings smaller. This is my thought, not a claim in the abstract.

There is nothing in the abstract about treatment. It does not appear that those who took medication and those who did not were compared, so no conclusion that medication raises or lowers these risks comes out of this study.

The sample is a single country and a single birth year. The diagnostic and recording practice of Finns born in 1987 may not be the same as that of a child born in Turkey today. Also the ADHD group is 228 people; results looked at with a small group are shakier.

Finally, an average does not describe the individual. A 2.45 for mood disorder does not mean that most children with ADHD will develop a mood disorder later. Since the abstract does not give absolute proportions, we do not know how many people it occurs in. We only know that the ADHD group received these diagnoses more often than the comparison group.

What is left for me

I read this study not as ADHD being a health risk but as ADHD being a diagnosis that calls for mental health follow-up. I liked the "no increase seen" result on the physical illness side, but I would keep it not as a guarantee but as an observation of this sample. A group of 228 is small for carrying that sentence.

What interests me most is how short the list is. What remains after strict adjustment are already the topics that most need to be talked about in the life of someone with ADHD: mood, anxiety, substance use. The time to look for treatment and support for these is, in my place, not to wait for the symptoms to get heavier. If you are looking after someone diagnosed in youth, or a child like that, do not hesitate to bring up these topics yourself in check-up visits.