according to a study presented at the annual meeting of the Society for Investigative Dermatology, held virtually.
“The risk increase ranges from as low as 5% up to 59%, depending on the outcome, with generally greater effects observed among the adults,” Joy Wan, MD, a postdoctoral dermatology fellow at the University of Pennsylvania, Philadelphia, said in her presentation. The risk was independent of other atopic disease, gender, age, and socioeconomic status.
Dr. Wan and colleagues conducted a cohort study of patients with AD in the United Kingdom using data from the Health Improvement Network (THIN) electronic records database, matching AD patients in THIN with up to five patients without AD, similar in age and also registered to general practices. The researchers validated AD disease status using an algorithm that identified patients with a diagnostic code and two therapy codes related to AD. Outcomes of interest included anxiety, depression, bipolar disorder, obsessive-compulsive disorder, ADHD, schizophrenia, and autism. Patients entered into the cohort when they were diagnosed with AD, registered by a practice, or when data from a practice was reported to THIN. The researchers stopped following patients when they developed a neuropsychiatric outcome of interest, left a practice, died, or when the study ended.
“Previous studies have found associations between atopic dermatitis and anxiety, depression, and attention-deficit/hyperactivity disorder. However, many previous studies had been cross-sectional and they were unable to evaluate the directionality of association between atopic dermatitis and neuropsychiatric outcomes, while other previous studies have relied on the self-report of atopic dermatitis and outcomes as well,” Dr. Wan said. “Thus, longitudinal studies, using validated measures of atopic dermatitis, and those that include the entire age span, are really needed.”
Overall, 434,859 children and adolescents under aged 18 with AD in the THIN database were matched to 1,983,589 controls, and 644,802 adults with AD were matched to almost 2,900,000 adults without AD. In the pediatric group, demographics were mostly balanced between children with and without AD: the average age ranged between about 5 and almost 6 years. In pediatric patients with AD, there was a higher rate of allergic rhinitis (6.2% vs. 4%) and asthma (13.5% vs. 9.3%) than in the control group.
For adults, the average age was about 48 years in both groups. Compared with patients who did not have AD, adults with AD also had higher rates of allergic rhinitis (15.2% vs. 9.6%) and asthma (19.9% vs. 12.6%).
After adjusting for age, gender, socioeconomic status, asthma, and allergic rhinitis, Dr. Wan and colleagues found greater rates of bipolar disorder (hazard ratio, 1.34; 95% confidence interval, 1.09-1.65), obsessive-compulsive disorder (HR, 1.30; 95% CI, 1.21-1.41), anxiety (HR, 1.09; 95% CI, 1.07-1.11), and depression (HR, 1.06; 95% CI, 1.04-1.08) among children and adolescents with AD, compared with controls.
In the adult cohort, a diagnosis of AD was associated with an increased risk of autism (HR, 1.53; 95% CI, 1.30-1.80), obsessive-compulsive disorder (HR, 1.49; 95% CI, 1.40-1.59), ADHD (HR, 1.31; 95% CI, 1.13-1.53), anxiety (HR, 1.17; 95% CI, 1.15-1.18), depression (HR, 1.15; 95% CI, 1.14-1.16), and bipolar disorder (HR, 1.12; 95% CI, 1.04-1.21), after adjusting for age, gender, socioeconomic status, asthma, and allergic rhinitis.
One reason for the increased associations among the adults, even for ADHD and autism, which are more characteristically diagnosed in childhood, Dr. Wan said, is that, since they looked at incident outcomes, “many children may already have had these prevalent comorbidities at the time of the entry in the cohort.”
She noted that the study may have observation bias or unknown confounders, but she hopes these results raise awareness of the association between AD and neuropsychiatric disorders, although more research is needed to determine how AD severity affects neuropsychiatric outcomes. “Additional work is needed to really understand the mechanisms that drive these associations, whether it’s mediated through symptoms of atopic dermatitis such as itch and poor sleep, or potentially the stigma of having a chronic skin disease, or perhaps shared pathophysiology between atopic dermatitis and these neuropsychiatric diseases,” she said.
The study was funded by a grant from Pfizer. Dr. Wan reports receiving research funding from Pfizer paid to the University of Pennsylvania.