Word-reading thresholds in Alzheimer disease and mild memory loss: a pilot study.
OBJECTIVE
To determine whether subjects with early Alzheimer Disease (AD) or Mild Cognitive Impairment (MCI) would demonstrate significant abnormalities on tests of word reading threshold (WRT), spatial contrast sensitivity (SCS), and color discrimination (CD).


METHODS
Prospective cohort study of 13 AD subjects, 13 subjects with Mild Cognitive Impairment (MCI), and 12 healthy elderly normal controls (ENC). CD was determined using the Farnsworth D-15 method. SCS was tested using a Vistech photographic chart. For WRT determination, pattern-masked words were presented successively at increasing target durations. The threshold was determined as the target duration at which 50% of the words were read.


RESULTS
The mean number of errors in Color Discrimination and Spatial Contrast Sensitivity did not differ significantly among the three groups. WRT was significantly longer in the AD group (122.6 +/- 70.8 ms) in comparison with ENC group (53.8 +/- 15.9 ms) (p < 0.001). A WRT threshold limit of 85 msec correctly classified 11/12 ENC subjects and 10/13 AD subjects. Four of the 13 MCI subjects also exceeded this threshold and all four progressed to AD within 2 year follow-up.


CONCLUSIONS
Word Reading Threshold determination discriminates mild AD subjects from ENC, and correlates with severity of cognitive impairment. It may have diagnostic and prognostic utility in early AD and MCI subjects.
Massoud
Fadi
F
Division of Geriatric Medicine, Centre Hospitalier de l'Université de Montréal, University of Montreal, Montreal, Québec, Canada.
Chertkow
Howard
H
Whitehead
Victor
V
Overbury
Olga
O
Bergman
Howard
H
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000523:psychology; D003072:Cognition Disorders / Q000175:diagnosis* / Q000523:psychology; D003118:Color Perception; D015350:Contrast Sensitivity; D004193:Discrimination Learning; D005260:Female; D006801:Humans; D008297:Male; D011939:Mental Recall; D009949:Orientation; D010364:Pattern Recognition, Visual; D011930:Reaction Time; D011932:Reading; D012684:Sensory Thresholds