Q-Motor, a promising motor-assessment tool for adults with Huntington’s disease, also provides non-invasive, easy, and sensitive measures to gauge motor function changes in children and adolescents, a study shows.
The data highlights Q-Motor’s potential to detect subtle motor changes associated with Huntington’s disease in at-risk youth.
The study, “A Feasibility Study of Quantitative Motor Assessments in Children Using the Q-Motor Suite,” was published in the Journal of Huntington’s Disease.
With the expected emergence of preventive gene therapies to halt or delay Huntington’s development — particularly in children and adolescents known to carry the disease-causing mutation — there is an increasing need for early, sensitive motor-assessment tools, researchers say.
“The ultimate goal for the HD [Huntington’s disease] community is to implement preventive treatments that ensure that disease manifestations in [Huntington’s] carriers can be delayed, or that affected individuals can live their lives free of HD,” Peggy C. Nopoulos, MD, professor of psychiatry, neurology and pediatrics at the University of Iowa Carver College of Medicine and the study’s senior author, said in a press release.
The Unified Huntington’s Disease Rating Scale Total Motor Score (UHDRS-TMS) is considered the gold standard for establishing the onset of motor symptoms in Huntington’s disease.
However, increasing evidence suggests that the Q-Suite Motor Assessment Tool (Q-Motor) — currently being used for exploratory assessments in multi-center trials of Huntington’s — is more sensitive to the disease’s subtle motor changes over time, and up to two decades before clinical diagnosis.
The Q-Motor test uses force transducers to provide measures of speed and self-paced tapping of fingers, hands and feet, grip strength, abnormal involuntary movements (chorea), and tongue strength.
While this tool seems to have the potential to detect motor function changes in young people at risk of developing the disease, the only Q-Motor measure evaluated in children to date has been tongue strength.
To fill this gap, researchers at University of Iowa Hospital and Clinics, along with colleagues in Germany, evaluated whether children and adolescents could complete Q-Motor tasks (all except for tongue strength), and whether they were sensitive to age-related changes in motor function.
The study involved 29 healthy participants between 6 and 17 years (mean age of 11.5 years), including 17 boys and 12 girls. Tasks included finger tapping, tapping hands, foot tapping, grasping and lifting, and assessment of involuntary movements.
The results showed that all participants were able to follow the instructions to complete the Q-Motor tasks, and that their performance was significantly associated with age.
Younger children exhibited slower tapping — except for hand tapping — more variability in tapping and grip strength tasks, and more involuntary movements than older children.
The researchers noted that these findings were consistent with previous data showing that as children grow, they increase their motor speed and improve their fine motor skills (coordination of small muscles which control the hands and fingers). The findings also complemented the results of the previous study assessing the tongue strength measure.
“We found that we can get reliable, quantitative measures of motor function in children with Q-Motor and that the equipment is sensitive to age-related improvements in motor function,” said Ellen van der Plas, PhD, the study’s lead author.
Q-Motor has not been validated by regulatory agencies yet, van der Plas noted.
However, these data highlight the non-invasive and easy-to-administer nature of Q-Motor tasks, and the test’s potential as “a suitable measure for studying subtle motor manifestations of [Huntington’s disease] in at-risk youth,” she said.
This may help guide decisions of when to start preventive therapies, which “may potentially have to be administered very early to child and adolescent carriers of the HD mutation,” the researchers said.
“The global network of HD clinics already equipped with Q-Motor devices due to its use in multiple global multi-center HD trials further supports this strategy and reduces costs,” the investigators said.
They emphasized, however, that additional studies, particularly in young children and those with juvenile Huntington’s disease, are required to confirm Q-Motor’s potential in assessing motor function changes in this young at-risk population.