A US study has found that ADHD can persist into adulthood for a third of people, with the Mail Online reporting on the story.
Attention deficit hyperactivity disorder (ADHD) is a group of behavioural symptoms that includes inattentiveness, hyperactivity and impulsiveness. Usually considered to be a childhood disease, this study adds to a body of evidence that suggests ADHD may continue to be a problem for some adults.
The study examined the long-term outcomes of children with the signs and symptoms of ADHD, compared with a control group of children who did not have the disorder.
The three most significant findings were:
- ADHD persisted in almost a third of people diagnosed with the disorder in childhood
- half of people with childhood ADHD suffered from at least one other psychiatric disorder as adults
- adults with childhood ADHD are at increased risk of death from suicide
However, these findings should be interpreted with caution. There were few deaths during the follow-up period, and even fewer from suicide – three deaths among 367 people who had childhood ADHD, and five among almost 5,000 people with no history of childhood ADHD. Risk calculations based on such small numbers could be inaccurate.
The study's findings are also limited by the fact that there is no agreed diagnostic criteria for adult ADHD.
Despite this, the results of this study suggest that children with ADHD need to be carefully followed up and supported into adulthood.
Where did the story come from?
The study was carried out by researchers from Boston Children's Hospital, the Mayo Clinic and Texas Children's Hospital in the US, and was funded by the US Public Health Service. Pilot work for part of the study was funded by McNeil Consumer and Specialty Pharmaceuticals.
The results of the study were covered well by the Mail Online.
What kind of research was this?
This was a combination of a cohort and case-control study. The study used data from a birth cohort of all children born between January 1 1976 and December 31 1982 in Minnesota Independent School District 535. People who fulfilled the inclusion criteria and gave permission for their medical and school records to be used were included.
The primary aim of the study was to determine whether people who had ADHD as a child were at increased risk of serious adverse outcomes, including death, compared with people who did not have ADHD as a child.
The birth cohort was followed up at an average age of 27. At this point, they were invited to participate in the case-control study, which compared the outcomes of people who had childhood ADHD with the outcomes for those who did not have childhood ADHD. The study aimed to determine some of the consequences of having ADHD as a child, such as:
- what proportion of people who had ADHD as a child had ADHD as an adult
- whether children and adults with ADHD are more likely to develop other psychiatric disorders
A cohort study with a long follow-up period is the ideal way to answer these sorts of questions.
What did the research involve?
The researchers analysed data for all children who fulfilled the inclusion criteria. Children were classified as having ADHD if their school or medical records contained records of symptoms consistent with ADHD, if they had positive ADHD questionnaire results, or if they had been diagnosed with ADHD. A total of 367 children with ADHD were identified and studied. The remaining 4,946 children were classified as not having ADHD.
When participants reached an average age of 27, the researchers determined whether they were alive or not and the cause of death if they had died.
The researchers also invited all the people who had ADHD as a child (the cases), and a selection of the people who did not have ADHD (the controls), to participate in a case-control study. The researchers determined whether participants had adult ADHD and whether they were suffering from other psychiatric disorders.
Of the 367 people who had ADHD as a child, 232 agreed to participate in the case-control study. A total of 335 people without ADHD were recruited as controls.
The outcomes for participants who had ADHD as a child were compared with the outcomes for participants who did not have ADHD.
What were the basic results?
The overall survival rate was similar for people with childhood ADHD and for people who did not have childhood ADHD. Seven of the 367 people with childhood ADHD died by the time the group was followed up. In the control group, 37 of 4,946 people had died. The standardised mortality ratio was 1.88 (95% confidence interval [CI] 0.83 to 4.26).
People with childhood ADHD were more likely to die by suicide (standardised mortality ratio from suicide 4.83, 95% CI 1.14 to 20.46). However, it should be noted that there were only actually three suicides in the ADHD group, making up just 1.2% of the total of the group.
Persistence of ADHD into adulthood and other psychiatric disorders
ADHD persisted into adulthood for 29.3% of childhood cases. People who had ADHD as a child were more likely than controls to have at least one other psychiatric disorder (56.9% versus 34.9%; odds ratio [OR] 2.6, 95% CI 1.8 to 3.8).
The most common adult psychiatric problems among childhood ADHD cases were:
- alcohol dependence/abuse
- other substance dependence/abuse
- antisocial personality disorder
- current or past history of a hypomanic episode
- generalised anxiety disorder
- current major depressive disorder
People who had persistent ADHD were also more likely to have another psychiatric disorder than people who had ADHD as a child but no longer fulfilled the ADHD criteria (80.9% versus 47.0%, adjusted OR 4.8, 95% CI 2.4 to 9.5).
How did the researchers interpret the results?
"Childhood ADHD is a chronic health problem, with significant risk for mortality, persistence of ADHD, and long-term morbidity in adulthood."
This study examined the long-term outcomes of ADHD. It found that people who had ADHD as children were at increased risk of death by suicide and of developing at least one psychiatric disorder as adults. It also found that almost a third of people had ADHD that persisted into adulthood.
The study has the advantage of being population based, rather than being performed on a selected population of children with ADHD. However, ADHD cases were identified on the basis of medical and school records, which means that some cases may have been missed. The study also has other limitations, some of which the researchers recognised themselves:
- There were relatively few deaths in the cohort, limiting the strength of any conclusions that can be drawn. In particular, although the study found an increased risk of suicide among people with childhood ADHD, there were only three suicides among 367 people with childhood ADHD and five among almost 5,000 people who did not have childhood ADHD. Risk calculations based on such small numbers may be inaccurate, as the wide size of the confidence interval around the 4.83 mortality ratio (1.14 to 20.46) suggests. The true figure could lie anywhere between these values.
- Not all people participated in the case-control study, which aimed to determine the persistence of ADHD and the presence of psychiatric disorders. There may have been differences between the people who participated and those who did not.
- There are no agreed standardised diagnostic criteria for adult ADHD. This means that some of the diagnoses of adult ADHD may have been incorrect, or people who have adult ADHD may not have been diagnosed.
- The researchers report that most participants were white and middle class, so the results of this study may not be generalisable to other populations.
Despite these limitations, the results of this study suggest that children with ADHD need to be carefully followed up and supported into adulthood.
If your son or daughter is being treated for ADHD and is due to be transferred into adult care services, or you are a young person being treated for ADHD, you should discuss the potential issues surrounding the transfer of your care with the care team.
It may be a good idea to ask to have a reviewed care plan drawn up that explains how your care needs will be met in the future.