Neurodegenerative and other chronic disorders among people aged 75 years and over in the community

Objectives: To assess age-related disease patterns in the older population in the community, especially the prevalence of neurodegenerative disorders and their association with systemic and vascular diseases. Design: Cross-sectional, community-based study. Setting: Area served by the Central Sydney Area Health Service, August 1991 to March 1994. Subjects: 647 people aged 75 years or over, living in the community; 537 (83%) underwent medical assessment. Outcome measures: Clinician diagnoses of chronic disease, including neurodegenerative disorders (cognitive and visual impairment, gait ataxia and slowing, dementia and Parkinson's disease); arteriopathy score; age-related trends; and correlations among diagnoses and arteriopathy score. Results: Subjects had mean age of 81.0 years (range, 75-97). The most common diagnosis was arthritis (women, 73%; men, 68%), while the most common neurodegenerative diagnoses were gait ataxia (women, 57%; men, 42%), visual impairment (women, 40%; men, 45%) and cognitive impairment (women, 39%; men, 36%). Neurodegenerative diagnoses increased significantly in prevalence with increasing age, while most systemic diseases tended to decrease, although not significantly. Dementia was diagnosed in 92 subjects (17%), with Alzheimer's disease being the most common cause, but many having multiple causes. Significant correlations were found between neurodegenerative diagnoses and between the arteriopathy score and stroke, but not neurodegenerative diagnoses. Conclusions: The increase in comorbidities in the older population arises from an age-related increase in neurodegenerative disorders. These form a cluster suggesting a common aetiologic process which is not arteriopathic.