Neurological signs, aging, and the neurodegenerative syndromes

Abstract

Objectives: To identify the prevalence of neurological signs said to be associated with "normal" aging in subjects 75 years and older. To examine the association of these signs with age, stroke, the neurodegenerative diagnoses (dementia, cognitive impairment, gait ataxia, gait slowing, and parkinsonism), and systemic diseases.

Design: Subjects participated in a standardized clinical history, examination, neurological evaluation, and neuropsychological assessment battery. A linear regression model that allowed the simultaneous consideration of multiple parameters was used to assess the independent contribution of age and disease to the presence of the signs. Correlations between the signs and age in the subgroup free of neurological diagnoses were performed.

Setting: Community-based study in Sydney, Australia.

Participants: A random sample of 647 community-dwelling subjects older than 75 years.

Main outcome measures: Standardized neurological examination in 537 subjects.

Results: With the exception of impaired vibration sense (beta = .009, P < .01), loss of upward gaze (beta = .005, P < .01), and bradykinesia (beta = .005, P < .01), all signs were associated with the neurodegenerative syndromes and stroke. Analysis of the subgroup free of neurological diagnoses confirmed these findings. Apart from impaired vibration sense of the thumbs (r = 0.22, P < .01) and gait instability (r = 0.20, P < .05), no significant associations with age were identified.

Conclusion: It is not aging to which many neurological signs should be attributed, but rather to the neurodegenerative syndromes that accompany aging.