medwireNews: A battery of motor, cognitive, and neuropsychiatric tests over 3 years can predict disease progression in patients with Huntington's disease (HD) before the development of overt symptoms, research shows.
"Understanding the natural history of neurodegenerative diseases such as HD, both before and after clinical onset, is crucial for optimisation of design of disease-modifying clinical trials," explain Sarah Tabrizi (University College London, UK) and TRACK-HD study co-authors.
"These studies will enable testing of treatment efficacy before clinical onset, when the chances of preventing further progression of the disease process are greatest."
The 3-year study included 58 patients carrying the mutant huntingtin gene who were expected, on the basis of age and CAG repeat length, to have at least 10.8 years before the onset of symptoms (preHD-A group) and 46 patients predicted to develop symptoms within 10.8 years (preHD-B group). In addition, the team followed up 66 patients in the early stages of HD with a functional capacity score of 11-13 (HD1) and 31 patients with a score of 7-10 (HD2), as well as 97 healthy controls.
As reported in TheLancet Neurology, preHD-B patients showed significant decline in motor and cognitive tasks at 3 years compared with controls, despite no significant change noted at the 2-year check up.
The symbol digit modality test was the most sensitive for detecting change in preHD-B patients over 3 years and the greatest psychiatric change detected was increasing apathy.
In addition, magnetic resonance imaging measurement of gray-matter volume and inter-tap interval significantly predicted clinical diagnosis of HD in preHD patients, even after controlling for CAG repeat length and age-related risk, report Tabrizi et al.
Among patients with early HD, both quantitative motor and cognitive changes significantly predicted total functional capacity and longitudinal changes. There was a significant correlation between neuropsychiatric changes associated with frontostriatal pathology and loss of functional capacity in the early HD groups.
Finally, age and CAG repeat length significantly explained variance in the changes over time across the battery of tests in the study participants, especially for preHD patients, the team concludes.
In an accompanying commentary, Francis Walker (Wake Forest Medical School, Winston-Salem, North Carolina, USA) discusses the use of clinical "road maps" for patient care by physicians and praises the authors for their "bold" article.
"Virtual roadmaps of disease in the minds of practitioners are good for care in the framework of the traditional patient encounter, but it takes substantial effort, teamwork, and genius to turn them into rigorous, quantifiable timelines that can be used to test efficacy in future therapeutic trials," he writes.
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