A U.S. dermatology physician said atopic dermatitis treatments could affect the patients’ mental health including attention deficit hyperactivity disorder (ADHD).

Analyzing data from the National Survey of Children’s Health, Eric Lawrence Simpson, a professor of dermatology at Oregon Health & Science University’s School of Medicine, released his study results that children with atopic dermatitis had 1.87 times higher chance of having ADHD than those without the disease.

Based on the survey on 92,642 children aged 0-17, the study showed that children with atopic dermatitis had 1.81 times higher incidence of depression, 1.77 times more of anxiety, 1.87 times more of conduct disorder, and 3.04 times more of autism. The interesting point was that when their skin problems subsided, their mental health improved.

In an interview with Korea Biomedical Review, Simpson talked about what physicians should consider when treating atopic dermatitis and its comorbidity with mental health.

Question: We heard that you participated in a study that researched on relations between atopic dermatitis and mental disorders. Is that right?

Answer: There have been many studies on relations between atopic dermatitis and mental health. I was also involved in a U.S. government-led study that surveyed more than 90,000 children in the U.S.

Fortunately, the survey included questions enquiring parents about their children’s health status about atopic dermatitis, asthma, anxiety, depression, and ADHD. We studied on whether pediatric atopic dermatitis patients had a different incidence rate of mental disorders such as ADHD, anxiety, and depression. We found that children with atopic dermatitis had more than double the chance of having a mental disorder than those without it.

Q: But such conclusion doesn’t mean that atopic dermatitis causes mental disorders like ADHD, does it?

A: It has not been fully explained yet why patients with atopic dermatitis have a high prevalence of mental disorders like autism and ADHD. There are many theories, and one of them is the genetic predisposition.

Another possible cause is a sleep disorder that chronic atopic dermatitis patients often experience. Several clinical trials showed that if people cannot sleep for several days, they show behaviors often displayed by ADHD patients.

A third theory is an inflammatory response. It’s a theory that inflammation causes mental disorders like ADHD and diseases like atopic dermatitis. If an inflammatory response occurs in early age, it can affect both mental health and atopic dermatitis. The causal relationship between mental health and inflammatory response is a hot topic discussed among the academic circles.

Q: It is already known that patients develop depression because of their diseases such as cancer. Should we look at mental disorders that develop after the onset of atopic dermatitis from another angle?

A: Disorders like ADHD do not always come from atopic dermatitis. But, if people suffer chronic diseases in childhood, they have a high chance of experiencing mental disorders like ADHD. However, there hasn’t been a clinical trial on the relationship between chronic disease period and the development of ADHD.

Moreover, there hasn’t been a separate study on ADHD’s complex phenotype. Thus, if a patient shows symptoms of ADHD, depression, and anxiety due to atopic dermatitis, we might be able to treat such mental disorders by treating atopic dermatitis. Some of the patients do not have any mental disorder but show some similar symptoms. If we treat their atopic dermatitis, we might get rid of the symptoms.

Q: You said treating atopic dermatitis could also treat mental disorders. Is there a clinical trial or a study to support the idea?

A: There is a representative study on 16-week treatment using dupilumab. The survey of adult patients with acute atopic dermatitis showed the patients saw their Hospital Anxiety and Depression Scale (HADS) going down by 40 percent after the treatment.

Q: Is the causal relationship between atopic dermatitis and ADHD confirmed?

A: Recently, there was a longitudinal study on ADHD and atopic dermatitis. It had a conclusion that atopic dermatitis occurs first and ADHD develops later, confirming the causal relationship between the two. However, we are not 100 percent sure.

Q: In reducing those symptoms, does dupilumab you mentioned earlier have a merit in particular?

A: We can’t say the only dupilumab reduces anxiety or depression. But it is a treatment to manage and control the symptoms of atopic dermatitis patients effectively. A proper treatment of the disease with an excellent drug can lead to good results regarding mental disorder treatment.

Q: Many Koreans tend to think that incidence of atopic dermatitis heavily depends on environmental conditions.

A: Some people believe a better environment could alleviate their child’s symptoms. But that doesn’t mean the disease is gone. There are people in the U.S. too who believe living in a stress-free environment like Hawaii can help reduce symptoms of atopic dermatitis. But not everyone can take that option. We must develop a treatment which can be used for everyone, regardless of their living environment and symptoms.

Some patients try out alternative medicine or specific diets for a cure, but they end up coming back to hospitals. As it is a chronic disease and difficult to cure, patients around the world including Korea have similarities.

It is quite sad to say that doctors can’t cure atopic dermatitis entirely, but I want to make it clear that we can bring back their normal life, before the onset of atopic dermatitis, through continued treatments.