Primary or depressive dementia: Psychometric assessment

Neuropsychological testing and assessment scales for dementia of the Alzheimer's type

Neuropsychological assessment plays an important role in the process of diagnosing DAT. Whereas the brief screens are sensitive to the cognitive deficits associated with DAT, full battery measures should be used to rule out early dementia or to differentiate among the various dementing illnesses. Following diagnosis, there are numerous assessment measures that facilitate management and placement decisions. These measures include instruments that help stage the illness to determine severity, instruments that evaluate the patient's capacity to perform activities of daily living, and measures that evaluate for the behavior symptoms common in later-stage dementia.

The neuropsychological differentiation of patients with very mild Alzheimer's disease and/or major depression

OBJECTIVE

To evaluate the usefulness of standardized neuropsychological tests in the psychometric differentiation of patients with very mild or mild Alzheimer's Disease (AD) and/or major depression presenting in a tertiary clinic with memory/attention complaints.

DESIGN

Controlled prospective clinicoexperimental design.

SETTING

Multidisciplinary Memory Clinic at Addenbroke's Hospital, Cambridge, England.

PARTICIPANTS

Twenty-four patients with a clinical diagnosis of Alzheimer's disease (12 with major depression and 12 without), 12 patients with major depressive illness but without AD, and 12 healthy control subjects, all matched for age, sex, education levels, and estimates of premorbid intellectual potential.

MEASUREMENTS

Mini-Mental State Examination (MMSE), Wechsler's Logical Memory (WLM) and Visual Reproduction (WVR), immediate and delayed reproduction, Wechsler's paired Associate Learning (WPAL), including the Easy and Hard subsets. Warrington's Recognition Memory for Faces (WRMF), Kendrick's Object Learning (KOLT) and Digit Copying (KDCT) Tests.

OUTCOME MEASURES

Minimum 2-year follow-up diagnosis.

RESULTS

Statistically, patients with very mild AD were distinguished clearly from those without AD on most tests of memory functions. Psychometrically, only KOLT and an index of retention on WLM and WVR were specific enough to avoid false positives, a requirement for second-stage tools. They also proved sensitive enough to suggest their role as first-stage instruments when screening for primary dementia in high-functioning patients scoring above the cut-point on MMSE.

CONCLUSIONS

As efforts intensify to develop more powerful means to identify patients with Alzheimer's disease in its earliest stages, inclusion of specialist tests posing greater cognitive challenge than standard mental status scales has been one strategy. Our study explored how some of these neuropsychological tools behave psychometrically when analyzed on a single-case basis, and the results suggest a few are sensitive enough to boost detection above base rates alone while also being specific enough to reduce false alarms. Retention on Wechsler's Logical Memory and Visual Reproduction tasks and scores on Kendrick's Object Learning Test helped decrease the degree of ambiguity when cognitive profiles were used to distinguish depressed patients with Alzheimer disease from those without.