Primary or Depressive Dementia: Mental Status Screening

Abstract

In the course of interviewing a patient, several aspects of everyday functioning must be covered to provide a range of observations necessary to suggest a provisional diagnosis. First organized by Adolf Meyer, the mental status examination consists of several techniques which, in recent times, have been shortened, structured and standardized to cover maximal ground in minimal time. In this article, the most popular scales are reviewed psychometrically for their capacity to detect, as first-stage instruments, cognitive impairment suggestive of primary dementia in the context of varying prevalence rates and confounding factors like sensory impairments, sociodemographics and depressive states. Several of the measures are found adequate in some respects though not in others, but all of the better ones, when used as front line implements during clinical intake, regularly improve detection over base rates. An analytical method modelled on ROC procedures is then described contrasting two of them before newer instruments are considered which aim to improve sensitivity at relatively little cost to specificity.

The Neuropsychological Differentiation of Patients with Very Mild Alzheimer's Disease and/or Major Depression

“…Specificity, the ability of a test to avoid falsely labeling as positive patients with cognitive impairment caused by conditions other than AD (i.e., functional depression), did not fall below .83 in any of the measures, a desirable feature when neuropsychological tests are used as second‐stage tools (see below). Taking account of estimated prevalence (base rates) in clinics similar to ours, 47,49 positive and negative predictive values reached their highest values when assessing a subject's recollection on Kendrick's pictorial memory test, along with her/his ability to retain material on Wechsler's tasks after a 30‐minute delay. Thus, 100% of cases failing the cut‐mark on either Wechsler's or Kendrick's tests were still thought to have AD at the last follow‐up (positive validity), whereas 72% (KOLT) or 64% (%WLM) of those passing the measures’ cut‐points were indeed free from AD (negative validity).…”

“…Two measures were particularly useful in identifying true cases, several of which had initially gone undetected on MMSE, a widely used mental status scale 49,98 . As in previous incidental reports, 10,65,99,100 Kendrick's pictorial learning test achieved moderate sensitivity, whereas its specificity was excellent.…”

“…Of these AD cases, KOLT managed to identify an additional 45%, as well as 100% of the mistaken ‘functional’ patients, a cardinal requirement for second‐stage tools. That sensitivity to mild AD was significantly extended over MMSE's own accuracy, without increasing the number of false alarms, suggests recent moves to include visuo‐perceptual components in newer short mental status scales could lead to increased detection in this population, particularly those patients with relatively greater nonverbal defi‐cits 49,85,86,103 . The ease of administration and patients’ acceptance of KOLT suggest this reliable test might also prove a useful adjunct in other contexts when sensitive screening devices are sought to investigate the presence of early AD (e.g., epidemiological surveys).…”

“…Controls were not reviewed in this way; however, most are seen regularly with the patients when the latter are reviewed at follow‐up. All controls had first been screened for mental status using a short scale 70 with excellent reliability and concurrent validity with longer measures of mental status (e.g., MMSE) 49 . Those scoring above the cut‐point on a short geriatric depression scale 71 were further referred for standard evaluation to rule out the presence of clinical depression (i.e., DSM‐III‐R diagnosis) but did not take part in this study.…”

“…In a recent survey of 4470 consecutive neurological admissions, 47 depressed patients with CNS symptoms accounted for 4% of the sample. There have been suggestions these patients have concomitant hippocampal damage from raised glucocorticoid levels 48 and cognitive impairment on conventional mental status scales used to screen for dementia associated with AD 49,50 . As more long‐term follow‐up studies are described, a proportion of these patients are found to have developed unmistakable signs of AD years later, 51–53 and it is now estimated that the rate of irreversible dementia in these patients is perhaps up to six times higher than that in other geriatric populations 26 …”