A breakthrough in ADHD research: A new study involving brain scans reveals that attention deficit hyperactivity disorder, ADHD, is not a uniform disorder but rather includes different subtypes with distinct brain foundations. The findings may lead to new approaches in the diagnosis and treatment of this common disorder.
The researchers analyzed 1,154 brain scans of children and adolescents and were able to identify three clear patterns, each representing a different subtype of the disorder. The first two subtypes are well known to physicians and the diagnostic system: A disorder characterized by difficulty concentrating, distractibility, and diversions, and a type that also includes hyperactivity, impulsivity, excessive movement, and restlessness. However, the most significant finding in the study is a third, more severe subtype, which combines classic symptoms with a profound difficulty in emotional regulation.
Among children belonging to this subtype, severe emotional outbursts, sharp mood swings, and intense reactions to frustrating situations were observed. These phenomena have been described for years by parents and teachers, yet they have not received official expression in accepted diagnostic definitions.
The central finding of the study is that the severe subtype not only presents more symptoms but is characterized by brain changes that are fundamentally different. The researchers found approximately 45 abnormal brain regions in these children, compared to only about 26 regions in the other two subtypes. This is both a quantitative and qualitative difference, suggesting a unique biological mechanism.
Two particularly prominent areas were found to be impaired in this subtype: The medial prefrontal cortex, responsible for decision–making and self–control, and the pallidum, an area associated with emotional regulation and motivation. The impairment in these areas may explain the extreme mood fluctuations and the difficulty in controlling emotional responses.
Although the idea of subtypes in ADHD has existed for about two decades, only in recent years has more accurate biological testing become possible through advanced imaging technologies. The researchers note that the new classification was discovered without the use of clinical data, but solely based on scans, which strengthens the biological validity of the findings.
The clinical significance of the discovery may be broad: Currently, the diagnosis of ADHD is based primarily on behavioral reports from parents and teachers and standardized questionnaires. However, when significant emotional components are present, the diagnosis becomes more complex and is sometimes confused with other disorders such as anxiety, depression, or behavioral disorders.
The ability to identify biological subtypes may allow for more precise treatment matching in the future. For example, children with the severe subtype may respond less to classic behavioral methods based on positive reinforcement. Conventional medications, primarily from the stimulant family, are also not always effective for them. In many cases, these children require more intensive treatment and sometimes receive a combination of several medications. Some are also diagnosed with additional disorders, which further complicates the management of the condition.
Nevertheless, the researchers emphasize that the use of brain scans for diagnostic purposes is not yet practical in routine practice. The tests are expensive, complex, and not accurate enough at the individual level. Therefore, as of today, diagnosis remains based on clinical criteria.
Despite the limitations, the scientific community views the study as an important step toward redefining the disorder. It is possible that in the near future, new criteria will be added to psychiatric diagnostic manuals that will also include the emotional regulation component. ADHD is one of the most common neurodevelopmental disorders, affecting about 11% of children in the United States. The understanding that this is a group of disorders rather than a single disorder may change the way it is addressed in the education system, in medicine, and in society as a whole.