Neuropsychological assessment of Alzheimer's disease

The overall objective of the neuropsychology task force of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) was to develop a brief, reliable battery of neuropsychological tests that would be widely used by researchers and clinicians to assess the cognitive status of patients with Alzheimer's disease (AD) at entry and during long-term annual follow-up.¹ The neuropsychological data on these patients and on cognitively normal control subjects, when correlated with clinical, neuropathologic, and neuroimaging findings, would then permit characterization of the natural history of this disorder. In addition, studies were undertaken to determine the relationship of test performance to demographic characteristics.^2,3

CERAD neuropsychological battery. Although the clinical presentation of AD varies from patient to patient, specific cognitive deficits inevitably appear, such as memory impairment, disorientation, loss of expressive and receptive language, and dyspraxia.⁴ Accordingly, the CERAD battery included tests to assess each of these cognitive domains.¹ The verbal fluency test assesses language production by asking the patient to name as many animals as possible within 60 seconds.⁵ A shortened version of the Boston Naming Test⁶ asks patients to name objects shown in 15 line drawings (five words each of high, medium, and low frequency). Other tests include the Mini-Mental State Examination (MMSE)⁷; a 10-item word list memory, recall, and recognition test; constructional praxis;⁸ and delayed recall of the praxis items. The battery usually requires 20 to 30 minutes to administer.

All of the neuropsychological tests were found to have substantial inter-rater reliability, with intraclass correlation coefficients ranging from 0.92 (constructional praxis) to 1.0 (word list recall). One-month test-retest reliability of these measures is shown in the table. It should be noted that lower values among control subjects reflect a limited response range due to ceiling effects. Longitudinal studies^{9 …}