About this Research Topic
In the arena of neurodegenerative disorders, many decades of research have started to give way to successive readouts on Alzheimer’s disease (AD),3 lewy body dementia (LBD)4 and amyotrophic lateral sclerosis (ALS)5 clinical trial results and increased clinical trials in frontotemporal dementia (FTD)6,7; all of which suggest we are on the cusp of effective disease modifying treatments for AD and other related dementias (ADRD). But one persistent challenge is accurate clinically meaningful outcome measurements, the expression of which is mediated by a myriad of factors and thus, are highly heterogeneous at the time of study measurement. The continued reliance on current FDA-approved legacy outcomes, which were all defined and validated using old methodologies and instruments has attenuated the promise of digital technologies in this field of research and care.
The race to find digital substitutes has also produced a new challenge. Misuse of the term “digital biomarkers” is rampant where any metric collected using a digital device or application is defined as such. The FDA has tried to clarify the difference between a clinical outcomes assessment (COA) and a digital biomarker; their position has been reinforced by others as well (Au et al, 2022; Hampel et al., 2022).9,10 Currently, most functional outcomes (e.g., gait, step counts, sleep, speech) obtained through digital devices are not specific to a certain etiology. They can decline due to many things other than cognition. Walking speed, for example, can lead to slowdowns due to joint pain or Parkinson’s disease (PD). Speech characteristics might change due to primary progressive aphasia (PPA), vascular dementia (VD) or AD. Cognitive or functional changes could also result from perioperative events. Digital biomarkers, on the other hand, are in the words of the FDA “a characteristic or set of characteristics, collected from digital health technologies, that is measured as an indicator of normal biological processes, pathogenic processes, or responses to an exposure or intervention, including therapeutic interventions.” Digital biomarkers require the same rigorous scientific investigation used to identify and validate biomarkers from blood, urine, cerebrospinal fluid and imaging and much research lies ahead to determined digital biomarkers that are specific to etiology and can meet FDA approval.
We are still in the nascent stage of the digital era and there is great clinical value in both digital COA and digital biomarkers that apply to brain related outcomes (cognitive, function, behavior, diagnosis). The purpose of this special issue is to invite papers that highlight both. For example, we welcome papers that illustrate specificity of digital COA in differentiating ADRDs (e.g., AD, FTD, LBD, vascular dementia, primary progressive aphasia, etc). We also welcome papers that are seeking to define and validate digital biomarkers, including those that test new methods and approaches and may be the first to set a precedent in which there is no prior published literature. Further, the added advantage of digital COA and biomarkers is their capacity to provide highly frequently monitored data which could transform how we run clinical trials including the duration of follow-up and required sample size. Therefore, we also welcome analytical innovations in this regard. We encourage submissions that are not bounded by the past or present and will add to the foundation of a future whose richness is still to be determined.
Keywords: Digital clinical outcome assessments (COA), digital biomarkers, Alzheimer’s disease and related disorders, digital technology, analytic innovations
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