S. Curran et J. Wattis, Critical flicker fusion threshold: A potentially useful measure for the early detection of Alzheimer's disease, HUM PSYCHOP, 15(2), 2000, pp. 103-112
Citations number
26
Categorie Soggetti
Neurosciences & Behavoir
Journal title
HUMAN PSYCHOPHARMACOLOGY-CLINICAL AND EXPERIMENTAL
Critical Flicker Fusion Threshold (CFFT) is a psychophysical threshold and,
in psychological terms, it is regarded as a measure of information process
ing capacity. CFFT has previously been shown to be a valid and reliable mea
sure in young healthy volunteers and it also has a long history of use as a
psychopharmacological measure in this group. Furthermore, the test satisfi
es many of the requirements of an 'ideal' measure for monitoring change, es
pecially in a psychopharmacological context. Despite this, CFFT has been ne
glected as a research tool in elderly and Alzheimer's disease (AD) populati
ons and was therefore investigated further in this regard. CFFT in communit
y-based healthy elderly subjects was normally distributed, but CFFT and asc
ending and descending thresholds were not significantly correlated with age
. The difference between ascending and descending thresholds was, however,
significantly correlated with age and this relationship appeared to be due
almost entirely to a change in the descending threshold. In addition, desce
nding thresholds were found to be significantly greater than ascending thre
sholds in healthy elderly subjects. In contrast, patients with AD were foun
d to have significantly lower CFFT and descending scores compared with heal
thy elderly subjects. Interestingly, descending thresholds were significant
ly lower than ascending thresholds in the patient group, a feature that may
be a characteristic of AD. Mean CFFT and ascending and descending threshol
ds were found to have a high test-retest, split-half and inter-rater reliab
ility, in addition to being significantly correlated with a number of psych
ometric measures, clinical scales and neuropsychological instruments common
ly used to assess patients with AD. CFFT is a quick and simple measure to a
dminister and patients had no difficulty completing the test. Because the m
easure is a psychophysical threshold, it is free from educational and cultu
ral bias and there are no floor or ceiling effects. From the results of thi
s work, CFFT appears to be a useful research tool in AD. It may be a suitab
le measure for monitoring cognitive change over time, either in community s
tudies of AD or a clinical trial context, but further work is required. The
technique might also contribute to the early detection of AD. This applica
tion would be particularly important because it would enable effective phar
macotherapies to be started early during the course of the illness before n
euronal damage is too advanced and this would have significant benefits for
patients. Copyright (C) 2000 John Wiley & Sons, Ltd.