Cognitive function, depression may be risk factors for AMD progression

Fort Lauderdale, FL-Data from a substudy within the Age-Related Eye Disease Study 2 (AREDS2) suggest that cognitive function and depression may be risk factors for progression to advanced age-related macular degeneration (AMD). The association only was found for general measures of cognitive function, however, said Traci E. Clemons, PhD, EMMES Corp., Rockville, MD. She also cautioned that it would be premature to place too much emphasis on the data, which were designed for hypothesis generation rather than testing.

AREDS2 is a randomized, multicenter, phase III study of the effect of lutein/zeaxanthin and omega 3 supplementation on the progression of vision loss from AMD; 4,203 participants are being followed for 5 years. A cognitive function substudy was incorporated since cognitive function is a major component of age-related deterioration, there are limited data regarding a possible association between cognitive function and AMD, and the few studies that have looked at this subject have been inclusive, Dr. Clemons said.

The cognitive function battery was administered via the telephone and consisted of seven instruments or tasks, a depression scale, and a hearing inventory. The instruments included a modified version of the Telephone Interview Cognitive Function Status (TICS); three measures of language and executive function (letter fluency, animal categories, and alternating fluency); measures of memory using the Logical Memory I and II instruments; and a backwards counting task that measures speed of processing. Self-reports of depression were measured using the Center for Epidemiology Studies Depression Scale.

Working with neurologists, the AREDS team developed a scoring method that converts raw scores from each task into disease scores, which then are averaged to provide a composite cognitive function score that minimizes floor and ceiling effects.

From the full enrollment of AREDS2, 3,369 individuals were included in the analysis of cognitive function presented by Dr. Clemons; 2,742 completed the full battery, while the remainder completed only the TICS instrument, the depression score, and the hearing assessment. The median age at baseline was 74 years; the majority of patients were female and Caucasian. Based on severity scores, 34% had advanced AMD.

Dr. Clemons reported that an association was found between decreased cognitive function, based on the composite score, and clinical severity scores; there was an increased risk of impairment for patients with advanced AMD in one eye compared to patients in the lower severity categories. There was also a trend toward a decreased score on the TICS with increased clinical abnormalities.

Results of separate instruments again showed an increased risk of impairment for patients with advanced AMD in one eye as well as for those with both pigment abnormalities and large drusen bilaterally.