ADHD is considered the most common neurodevelopmental disorder in the world. In recent years, more and more children have been diagnosed with ADHD, which can be attributed to increased awareness, changed diagnostic criteria, and reduced stigmatization.
– Children with ADHD form a highly heterogeneous group, and not receiving the right support can have significant consequences. A confirmed diagnosis is often necessary to ensure that the patient receives proper treatment and assistance, especially within the school environment, says Peik Gustafsson, senior physician in child and adolescent psychiatry at Psychiatry Skåne, associate professor at Lund University, and initiator of the study.
Presently, ADHD diagnosis relies primarily on interviews and observations, leading to uncertainty in clinical assessment. Although some neuropsychological tests are occasionally used, they lack sufficient precision. Consequently, ADHD diagnosis varies significantly between countries, including Sweden, depending on the evaluator. Hence, better diagnostic tools are needed.
– Previous research indicates a link between ADHD and structural changes in the cerebellum, where certain areas are smaller in ADHD cases. As the cerebellum plays a crucial role in motor skills and timing, we aimed to employ a test associated with these functions, explains Anders Rasmussen, associate professor in neurophysiology and a researcher at Lund University who led the study.
The researchers utilized finger-tapping, a test measuring a person's ability to perform rapid and regular movements with one or more fingers. Typically used to assess motor control, coordination, and temporal precision.
– The test, developed by Guy Madison at Umeå University, involves the child pressing a sensor, such as a keyboard, to the rhythm of a recurring sound. When the sound stops, the child continues pressing with their fingers just as before and at the same pace, clarifies Anders Rasmussen.
The results were remarkably clear. There was a significant difference between the ADHD group and the control group, with the former struggling to maintain the pace independently. Additionally, variations were observed among different subgroups within ADHD, where children without motor difficulties found it slightly easier to sustain a steady rhythm compared to children with ADHD accompanied by motor difficulties (DAMP), who faced the most challenges. The study demonstrates that finger-tapping can serve as an inexpensive, objective, and unbiased biomarker to complement current diagnostic methods.
–Our study is relatively small, and our ambition now is to continue research with larger groups of children, including those with autism, as they also exhibit significant changes in the cerebellum, concludes Peik Gustafsson.
