Diagnostic Approach for Dementia

Core Diagnostic Criteria

• Dementia is diagnosed when cognitive or behavioral symptoms interfere with ability to function at work or usual activities, represent a decline from previous functioning, and are not explained by delirium or major psychiatric disorder 1, 2
• Key cognitive domains to assess include memory, executive function, visuospatial abilities, language functions, and personality/behavior changes 1, 2
• Obtaining corroborative history from a reliable informant about changes in cognition, function, and behavior is essential for accurate diagnosis 1, 3

Diagnostic Assessment Process

Step 1: Clinical History and Examination

• Collect detailed information about cognitive concerns, including onset and progression of symptoms, sleep and mood disturbances, past medical history, family history, medication use, and review of systems 3
• Assess impact on instrumental activities of daily living (managing finances, medications, transportation, household tasks) 1

Step 2: Cognitive Assessment

• Use standardized cognitive screening tools such as the Mini-Mental State Examination (MMSE) - high sensitivity for moderate dementia 1, 2
• The Montreal Cognitive Assessment (MoCA) is more sensitive for mild cognitive impairment 2
• The Clock Drawing Test is a useful supplementary screening tool 1, 3
• Consider neuropsychological evaluation when patient presentation is complex or symptoms are mild/unusual, or when patient has educational extremes or language/cultural considerations 4, 5

Step 3: Laboratory Testing

• Recommended core laboratory tests include complete blood count, thyroid function tests, serum vitamin B12 levels, comprehensive metabolic panel, glucose levels, and calcium levels 1, 3, 6

Step 4: Neuroimaging

• Anatomical neuroimaging (MRI preferred over CT) is recommended, particularly when onset of cognitive symptoms is within the past 2 years, or when there is unexpected decline in cognition/function, recent significant head trauma, unexplained neurological manifestations, or significant vascular risk factors 1, 3

Tiered Approach to Specialized Testing

• Tier 1: Standard clinical evaluation with cognitive screening and core laboratory tests is sufficient for many patients 4, 5
• Tier 2: Consider specialized testing based on clinical presentation, including neuropsychological evaluation, advanced neuroimaging, and biomarker testing in select cases 4, 5

Diagnostic Formulation

• The diagnostic formulation should include three components: cognitive functional status, characterization of the cognitive-behavioral syndrome, and likely etiology/differential diagnosis 1, 4, 5

Common Pitfalls to Avoid

• Failing to obtain corroborative history from an informant 3
• Overlooking potentially reversible causes of cognitive impairment 2
• Using a "shotgun approach" to diagnostic testing rather than a tiered, methodical approach 4, 5

Follow-up and Monitoring

• Schedule follow-up visits every 6-12 months to track disease progression 1, 2
• Use a multi-dimensional approach to monitor cognition, functional autonomy, behavioral symptoms, and caregiver burden 1
• Reassess cognitive, functional, neuropsychiatric, and behavioral symptoms at each follow-up 2