A research article published on 6 August 2025 in Aging-US (Volume 17, Issue 8) is entitled “Age-related trends in amyloid positivity in Parkinson’s disease without dementia.” The study, led by first author Keiko Hatano and corresponding author Masashi Kameyama of the Tokyo Metropolitan Institute for Geriatrics and Gerontology in Japan, examined how age influences the prevalence of amyloid accumulation in individuals with Parkinson’s disease (PD) who do not present with dementia.
The researchers reported that patients diagnosed with PD in their eighties exhibited a markedly higher rate of amyloid positivity—an indicator commonly associated with Alzheimer’s disease—compared with those diagnosed at a younger age. Crucially, none of the participants had developed dementia at the time of assessment. This finding suggests that older individuals with PD may be at increased risk of subsequent cognitive decline and may benefit from early screening for Alzheimer ‘s-related pathological changes.
Amyloid-beta is widely recognised as a key biomarker of cognitive impairment. Although its role in the development of PD with dementia is well established, its contribution in patients who remain cognitively intact has been less clear. The aim of this investigation was therefore to clarify the impact of age on amyloid accumulation in PD patients without dementia.
The study included 89 participants diagnosed with PD but free of dementia, who were stratified into two age groups: those diagnosed before the age of 73 (LOW group) and those diagnosed at 73 years or older (HIGH group). Cerebrospinal fluid samples were analysed to measure amyloid-beta concentrations, a standard approach for detecting early Alzheimer ‘s-related changes. Results showed that 30.6% of the older cohort tested positive for amyloid, in contrast to only 10.0% of the younger group. As the authors summarised: “[…] we elucidated the prevalence of amyloid positivity in patients with PD without dementia, whose mean age at diagnosis was 80.2 years, using CSF Aβ42 levels.”
One unexpected observation was that amyloid positivity was less frequent among PD patients of both age groups compared with cognitively normal older adults in the general population. This counterintuitive result suggests that Parkinson’s disease may alter the trajectory of amyloid accumulation, potentially shortening the preclinical phase during which amyloid silently builds up in the brain before symptoms emerge. The authors propose that this dynamic may hasten the progression from preserved cognition to dementia in PD. The study further identified age-related associations with other Alzheimer ’s-related biomarkers, including elevated tau protein levels.
Against the backdrop of global population ageing and the increasing prevalence of PD among older adults, these findings carry important implications. They highlight the value of biomarker screening to identify individuals at risk of accelerated cognitive decline and emphasise the need for therapeutic strategies aimed at delaying or preventing the onset of dementia in Parkinson’s disease.
More information: Keiko Hatano et al, Age-related trends in amyloid positivity in Parkinson’s disease without dementia, Aging-US. DOI: 10.18632/aging.206297
Journal information: Aging-US Provided by Impact Journals LLC
