Enhanced stimulus contrast normalizes visual processing of rapidly presented letters in Alzheimer’s disease

• Published in: Vision research (Oxford) Vol. 45; no. 8; pp. 1013 - 1020
• Main Authors: Gilmore, Grover C., Cronin-Golomb, Alice, Neargarder, Sandy A., Morrison, Sarah R.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2005; Elsevier Science
• Subjects: Aged; Aged, 80 and over; Aging; Alzheimer Disease - physiopathology; Alzheimer Disease - psychology; Alzheimer’s disease; Biological and medical sciences; Cognition; Contrast; Contrast Sensitivity; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Masking; Medical sciences; Neurology; Pattern Recognition, Visual; Perception; Perceptual Disorders - etiology; Perceptual Disorders - physiopathology; Perceptual Disorders - psychology; Perceptual Masking; Photic Stimulation - methods; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Sensory Thresholds; Vision; Visual Acuity; Aging; Cognition; Masking; Alzheimer’s disease; Contrast; Human; Vigilance; Nervous system diseases; Senescence; Healthy subject; Alzheimer disease; Attention; Cerebral disorder; Letter; Vision; Central nervous system disease; Information processing; Perception; Degenerative disease; Developmental stage; Alzheimer's disease; Comparative study
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/j.visres.2004.10.017

Deficient perception and cognition in Alzheimer’s disease (AD) has been attributed to slow information processing and attentional disturbance, but an additional explanation may be reduced signal strength. In 21 individuals with probable AD, 29 healthy older and 54 younger adults, we enhanced the contrast level of rapidly-flashed masked letters. The AD group reached identification criterion (80% accuracy), but required significantly higher contrast than the control groups. A source of the prevalent masking deficit may be reduced signal strength arising from dysfunction of retina or visual cortex. Increasing stimulus contrast may be an effective means of enhancing cognitive performance in AD.