A Primer in Neuropsychological Assessment for Dementia

Neuropsychological assessments are designed to identify the extent and severity of a patient’s cognitive and behavioral impairments. They allow us to determine a pattern of relative cognitive strengths and weaknesses, which indirectly yields information about the structural and functional integrity of a patient’s brain. Neuropsychologists use standardized tests to evaluate cognitive abilities such as attention, memory, language, processing speed, visuospatial, and executive functions.1 These types of comprehensive assessments are time-consuming and not always feasible or necessary in routine clinical practice. For neurologists, brief cognitive screening tasks can provide a quick estimate of a patient’s cognitive function and identify those who would benefit from a more detailed cognitive evaluation. Commonly used cognitive screening tools include the Mini-Mental Status Examination (MMSE)2 and the Montreal Cognitive Assessment (MoCA).3 The MMSE is heavily weighed towards orientation and memory, and, as such, may be insensitive to cognitive deficits encountered in non-Alzheimer’s disease dementias. The MoCA evaluates a broader range of cognitive abilities, thereby providing higher sensitivity to detect mild cognitive impairment.4 Slightly longer and more comprehensive screening tools such as the Addenbrooke’s Cognitive Examination,5 Dementia Rating Scale,6 and the Philadelphia Brief Assessment of Cognition7 can be particularly helpful in differential diagnosis given their inclusion of additional cognitive and behavioral domains. Despite the utility of general cognitive screening instruments, these may not be adequate for all patients. In fact, common cognitive screening tools may have poor sensitivity in highly educated individuals, or classify healthy subjects as impaired given their low educational attainment, primary language, or cultural background. Referral to a neuropsychologist is warranted in the following cases: • There is a clear discrepancy between cognitive screening scores and patient or caregiver reports of actual cognitive functioning; • The patient is younger than 65 years of age; • The patient presents with a focal impairment that may not be adequately captured by general screening instruments (e.g., visuospatial abilities, behavior); • The clinician suspects mild cognitive impairment (MCI) and would benefit from a detailed baseline assessment to track longitudinal progression.