From the Guidelines
The best diagnostic test for dementia in an 83-year-old man is the Montreal Cognitive Assessment (MoCA) due to its high sensitivity for detecting mild cognitive impairment and its ability to track progression through mild to moderate dementia. This is based on the most recent evidence from the Alzheimer's Association clinical practice guideline for the diagnostic evaluation, testing, counseling, and disclosure of suspected Alzheimer's disease and related disorders (DETecd-ADRD) 1. The MoCA is a widely available and well-suited test for detection of mild cognitive impairment (MCI) and tracks progression through mild to moderate dementia, with a range of 0-30 (max performance) and domain index scores that can help delineate the pattern of performance on cognitive domains.
When choosing a diagnostic test for dementia, it is essential to consider the patient's characteristics, such as level of education and occupational attainment, language, and cultural considerations. The MoCA is available in multiple languages and has been adapted for telemedicine, making it a versatile option for different patient populations. In contrast, the Mini-Mental State Examination (MMSE) is widely known and well-studied but has limitations, such as a lack of sensitivity for detecting mild dementia or MCI, and is subject to user fees due to copyright protection.
A comprehensive diagnostic approach should also include laboratory tests to rule out reversible causes, such as complete blood count, comprehensive metabolic panel, thyroid function tests, vitamin B12 levels, and syphilis serology. Brain imaging with MRI is preferred over CT scan, as it provides better visualization of brain structures and can identify vascular changes, atrophy patterns, and other structural abnormalities. Additional testing may include neuropsychological assessment for detailed cognitive evaluation and, in select cases, cerebrospinal fluid analysis for Alzheimer's biomarkers (amyloid-beta and tau proteins) 1.
The diagnostic process should also include a thorough history from both the patient and a reliable informant, focusing on the onset and progression of symptoms, functional status, and behavioral changes. Informant-based questionnaires, such as the Ascertain Dementia 8-Item Informant Questionnaire (AD8) or the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), can be useful in capturing incident cognitive decline and should be considered as part of the diagnostic evaluation 1.
Key considerations for the diagnostic test include:
- Time to administer: 10-15 minutes for MoCA
- Cognitive domains assessed: learning and memory, visuospatial, executive functions
- Sensitivity and specificity: MoCA has high sensitivity for detecting MCI and moderate dementia
- Availability: MoCA is widely available and can be adapted for telemedicine
- Limitations: MoCA may not be suitable for patients with low education or those who are not fluent in the language of the test.
From the Research
Diagnostic Tests for Dementia
The diagnostic tests for dementia include:
- Mini-Mental State Examination (MMSE)
- Mini-Cog test
- Addenbrooke's Cognitive Examination-Revised (ACE-R)
- Montreal Cognitive Assessment (MoCA)
Performance of Diagnostic Tests
The performance of these tests is as follows:
- MMSE: sensitivity of 0.81 and specificity of 0.89 2
- Mini-Cog test: sensitivity of 0.91 and specificity of 0.86 2
- ACE-R: sensitivity of 0.92 and specificity of 0.89 2
- MoCA: sensitivity of 0.89 and specificity of 0.75 for mild cognitive impairment 2
Comparison of MMSE and MoCA
MMSE and MoCA are comparable as cognitive assessment tools to monitor cognitive changes 3
- MMSE scores were moderately related to MoCA scores, which got stronger along with the time of follow-up 3
- MoCA is a more sensitive instrument than the MMSE to screen AD or DLB patients from non-dementia cases 4
Application of Diagnostic Tests in Different Types of Dementia
The application of these tests in different types of dementia is as follows: