Introduction: There is interference between emotional factors and intellectual output in the elderly, in whom there is a high prevalence of depression. Low output in conventional psychological tests may lead to false positive diagnoses of dementia.
Patients and methods: We evaluated 48 patients aged between 50 and 84 years with regard to their emotional and intellectual state by means of the SCAN system. We also used a test designed by ourselves to implicitly examine memory. This consisted of a task involving naming objects. Six stimuli were repeated three times, seeking an effect of perceptual representation of 'priming' which facilitated later recall.
Results: The results showed that patients with dementia recalled 0 to 2 of the repeated stimuli, as a result of weakened priming. Meanwhile the non-demented persons, in spite of having other neurological disorders answered between 4 and 6 times. Multivariate analysis of the variance showed that measurement of memory, both implicit and explicit, allowed discrimination between patients with and without dementia. However, the explicit results were not independent of the effects of depression.
Conclusions: Implicit measurements of memory were superior to direct or explicit measurements in the diagnosis of dementia. Patients with other degenerative conditions, such as Parkinsonism and multisystemic atrophy, had above average results. This corroborates the view that the neurological basis of this type of memory is not at subcortical level.