Abstract
Abstract: :
Purpose: To assess: 1) whether sensory (vision and hearing) impairment influences cognitive function assessment and vice–versa, 2) whether sensory impairment is associated with cognitive impairment. Methods: We recruited 208 participatns aged 65+ years, with no profound dementia or language difficulties, being assessed for aged care services at Westmead Hospital, Sydney during 2003. Visual impairment was defined as mild (<20/40, ≥20/80), moderate to severe (<20/80) in the better eye. Moderate and severe hearing loss were defined as pure–tone average air conduction hearing threshold > 40dBHL (decibels hearing level) and > 60dBHL (500–4000Hz, better ear) respectively. Cognitive function was assessed using the Mini–mental State Examination (MMSE). Results: After adjusting for age, sex and history of stroke, mean MMSE scores were 27.2±0.3, 26.3±0.8 and 24.0±1.1 for groups with normal vision, mild to moderate, and severe visual impairment, respectively (p for trend =0.02). After excluding either 3 or 5 vision–related MMSE items, the decreasing trend in mean MMSE as vision worsening remained but became non–significant, p(trend)=0.17 and 0.14 respectively. In persons with normal vision, the adjusted mean number of letters read correctly was similar between persons with normal (MMSE ≥24) and impaired (MMSE ≤ 23) cognitive function (48.0±0.7 vs 47.3±2.3 letters). In persons with mild or worse visual impairment, the corresponding adjusted mean number of letters read correctly was lower for those with cognitive impairment (19.1±5.4) than for those with normal cognitive function (27.4±3.0). No difference in adjusted mean hearing thresholds was observed between persons with normal and impaired cognitive function, after stratifying by hearing category: none or mild hearing loss (31.6±1.1 vs 28.8±2.7dB) and moderate to severe hearing loss (57.6±1.8 vs 56.6±3.6dB). No difference in adjusted mean MMSE scores was found between persons with none or mild (26.3±0.5) and moderate to severe hearing loss (26.2±0.5). Findings were similar after excluding 5 persons with MMSE ≤ 17. Conclusions: Our findings indicate: 1) visual impairment can partially influence MMSE measurement, while mild cognitive impairment appears to have no major effect on assessment of sensory function; 2) Vision impairment, but not hearing loss, is associated with cognitive decline in aged care services clients.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • aging • visual impairment: neuro–ophthalmological disease