Incidence of Cognitive Impairment in AMD and GA
The authors of the following Korean case-control study investigated cognitive function in patients with early and late age-related macular degeneration (AMD) compared with an elderly, community-dwelling Korean population without AMD.
They enrolled 170 AMD patients and 190 non-AMD community-based controls and a comprehensive battery for cognitive function evaluation consisting of 15 psychological tests, including a depression evaluation test, was used. They adjusted cognitive function scores for age, gender, education, and visual acuity (VA) and categorized AMD as early AMD, exudative AMD, or geographic atrophy. The primary outcome measure was the degree of cognitive impairment, as assessed by the Korean versions of the Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Assessment Battery, Benton Visual Retention Test, and Digit Span Test Forward and Backward.
Patients with AMD showed lower global cognition scores than did normal controls (mean Mini-Mental State Examination [MMSE] score, 24.97 vs 25.99; p<0.001), the authors noted. They also reported that, among cognitive functions, visuospatial function, verbal memory, visual memory, and frontal function were impaired in AMD patients relative to normal controls. Additionally, the study authors found that the rate of mild cognitive impairment (MCI) was higher in AMD patients than in controls (52.4% vs 26.8%; p<0.001), with an odds ratio (OR) of 3.127 (95% confidence interval, 1.855–5.271) after adjustment for age, education, and VA. Geographic atrophy was associated with the highest risk of MCI (OR, 4.431; 95% confidence interval, 1.413–13.898) and a clinically significant reduction in MMSE scores (23.42) relative to the controls. Furthermore, the authors observed a trend of worsening cognitive function test scores from the controls to the early AMD, then the exudative AMD, and finally the geographic atrophy patients, after adjustment for covariates. AMD patients with poor VA (≤20/100) had 6 times the risk of MCI as AMD patients with good or moderate VA (>20/100).
To conclude, patients with AMD—especially those with the geographic atrophy subtype—are at greater risk for cognitive impairment than are non-AMD control subjects. In the visual rehabilitation of AMD patients, potential cognitive impairment should be taken into consideration.