While it’s possible that residual effects of SARS-CoV-2 could lead to an eruption of attention-deficit/hyperactivity disorder (ADHD) cases, a debate at the World Congress on ADHD – Virtual Event underscored the fact that this is still a hypothesis. The bottom line is there needs to be more data, said Luis Augusto Rohde, MD, PhD, cochair of the congress’ scientific program committee and moderator of the session, “Residual effects of the 2019 pandemic will mirror the 1918 pandemic: Will we have lots of new ADHD cases?”
Dr. Luis A. Rohde
Considering the current pattern of the pandemic, there is not enough evidence for this to be a concern, Dr. Rohde said in an interview.
James Swanson, PhD, professor of pediatrics at the University of California, Irvine, opined that biological co-effects of COVID-19 are likely to have selective effects in children that may produce symptoms representative of ADHD. Using the 1918 Spanish flu pandemic as a historical reference, he estimated that COVID-19 would produce 5 million individuals with new-onset symptoms related to ADHD. “If these cases meet DSM-5 or ICD-11 criteria, there will be lots of new ADHD cases,” he predicted.
David Coghill, MD, a professor of child adolescent mental health at the University of Melbourne, observed that the sums Dr. Swanson presented “are based on maxing out the potential rather than looking at the sums more realistically.”
Could the 1918 pandemic offer clues?
In a commentary, Dr. Swanson and Nora D. Volkow, MD, wrote about “lessons learned” from the 1918 pandemic, and how residual sequelae in that era led to a condition labeled hyperkinetic syndrome in children. “It may be worthwhile to consider the hypothesis that the COVID-19 pandemic may result in a novel etiologic subtype of ADHD that clinicians may recognize in patients in the future,” wrote the commentators.
In survivors of the 1918 pandemic, brain inflammation or encephalitis sometimes emerged as residual sequelae, said Dr. Swanson. In some adult cases, these symptoms were diagnosed as “encephalitis lethargica” (EL) and were associated with Parkinson’s disease. In 1930, based on patients evaluated after 1918, researchers Franz Kramer and Hans Pollnow at Charité Hospital in Berlin described the behavioral manifestation of EL in children as hyperkinetic syndrome, a condition that was characterized by symptoms similar to the properties of ADHD: lack of concentration, insufficient goal orientation, and increased distractibility. “They even reported on autopsy cases that described brain regions that we now know are associated with ADHD from decades of brain imaging studies,” said Dr. Swanson.
COVID-19 rarely results in severe respiratory problems in children but the absolute number requiring hospitalization has accumulated and is now relatively large, said Dr. Swanson. One study of 1,695 severe COVID-19 cases in children and adolescents used MRI and detected neural effects in specific brain regions such as basal ganglia and frontal lobes that previous research had associated with ADHD. Approximately 22% of these rare but severe cases had documented neurologic involvement, and studies of affected children with mild or none of the initial respiratory symptoms of COVID-19 also detected similar selective effects in these brain regions.
A recent survey of medical records of 80 million people that identified 240,000 COVID cases (mostly adults) revealed that a third had neurological and psychiatric sequelae. Dr. Swanson also mentioned an article he wrote more than a decade ago on environmental as well as genetic factors that resulted in etiologic subtypes of ADHD, which provided a model for the impact of COVID-19 on specific brain regions that are associated with ADHD.
So far, the COVID-19 pandemic has produced 150 million cases worldwide and there are about 100 million survivors, setting an estimate of a maximum number of cases with residual sequelae. “I think that severe COVID-19 will probably be related to severe residual sequelae, and that mild or asymptomatic COVID-19 may be associated with less severe residual sequelae, which may resemble ADHD” said Dr. Swanson. If one-third of the cases manifest in some neurologic or psychiatric systems, this means 27 million would have residual sequelae. If 20% have impaired concentration or brain fog, this could result in about 5 million ADHD cases, he said.