Reliability of flicker threshold measurement in patients with primary degenerative dementia of the Alzheimer's type (PDDAT)

The test-retest and split-half reliability of flicker threshold measurement was determined in 23 female and three male patients with primary degenerative dementia of the Alzheimer's type (PDDAT). Patients had a mean age of 81.7 ± 6.05 years (range 67–89). Diagnosis of PDDAT was based on DSM-IIIR criteria. The psychophysical method of limits was used to determine the flicker threshold and was the average of four separate measurements. The split-half reliability was found to be 0.97 and the test-retest reliability 0.941 (both p < 0.0001). The measurement of flicker thresholds is a quick, easy and reliable technique in patients with PDDAT. Future work will also need to examine the validity and pharmacosensitivity of the measure if it is to be used to assess potentially therapeutic agents for the management of the underlying disease process.