What is the initial step in testing for dementia?

Initial Testing for Dementia

The initial step in testing for dementia is obtaining a detailed history from both the patient and an informant/care partner, followed by administration of a validated cognitive assessment tool (Tier 1 testing), which should be performed before proceeding with any laboratory or imaging studies. 1

Foundational First Steps

The 2025 Alzheimer's Association guidelines emphasize that the evaluation must begin with establishing a patient-centered partnership and obtaining comprehensive historical information before any formal testing occurs 1. This structured approach requires:

History Gathering (Core Element 1)

• Obtain corroborated history from an informant or care partner - this is critical and should occur in most situations, as patients may lack insight into their cognitive decline 1, 2
• Document specific cognitive and behavioral symptoms, their onset, progression, and impact on daily functioning 2
• Review medication lists, as drug toxicity accounts for approximately 9.5% of dementia cases 3
• Assess for depression and psychiatric symptoms, which are among the most common potentially reversible causes 4

Validated Cognitive Assessment (Tier 1 Testing)

After history-taking, administer a standardized cognitive instrument directly to the patient 1. The guidelines recommend familiarity with at least one validated tool:

• Montreal Cognitive Assessment (MoCA) - more sensitive for detecting MCI than MMSE 1, 5
• Mini-Cog - brief screening option 1
• RUDAS - comprehensive tool when more time is available 5
• Memory Impairment Screen (MIS) or SLUMS Examination 1

The Mini-Mental State Examination (MMSE), while widely known, has significant limitations including poor sensitivity for early MCI, lack of standardization, and copyright restrictions 1.

Critical Timing Consideration

Two or more problem-focused visits are typically required in primary care to complete the initial evaluation properly, especially when involving an informant and allowing sufficient time for validated cognitive testing 1.

Multi-Tiered Diagnostic Approach

The 2025 guidelines emphasize a structured, multi-tiered approach beginning with Tier 1 assessments before proceeding to additional testing 1. This means:

• Complete history and cognitive assessment FIRST
• Then proceed to "cognitive lab panel" (not "reversible dementia labs" - this terminology is misleading) 1
• Structural neuroimaging follows after initial clinical assessment 2, 6

What Tier 1 Laboratory Testing Includes

The conditions evaluated in routine lab panels rarely cause dementia as the primary etiology but often exacerbate underlying neurodegenerative disease 1. Essential screening includes:

• Thyroid-stimulating hormone (TSH) 6, 3
• Vitamin B12 levels 6, 4
• Complete blood count 3
• Comprehensive metabolic panel (sodium, calcium, glucose) 3

Important caveat: While 23% of patients may have potentially reversible conditions identified, actual reversal of dementia occurs in only 3.6% of cases, and these patients typically have milder cognitive deficits (mean MMSE 26) 7. This underscores why the primary goal is identifying exacerbating factors rather than expecting complete reversal.

Critical Pitfall to Avoid

Never assume "normal aging" without proper evaluation 1. Any patient with cognitive or behavioral symptoms concerning for decline should undergo formal assessment - this represents fundamental best medical practice 1.

Delirium Must Be Excluded First

Before proceeding with dementia evaluation, rule out delirium, which represents a medical emergency 1. Delirium features acute onset, fluctuating course, inattention, and altered consciousness - when superimposed on dementia, it accelerates decline and increases mortality 1.

When to Proceed Beyond Initial Testing

After completing Tier 1 assessments (history, informant input, validated cognitive testing, basic labs), the clinician should formulate whether 1:

1. The patient is cognitively unimpaired - no further testing needed
2. There is high confidence in a typical AD dementia presentation - may proceed to diagnosis disclosure
3. Atypical features, early onset (<65 years), or rapid progression - requires subspecialty consultation and higher-tier testing (neuropsychological testing, advanced imaging, CSF biomarkers) 1, 2

Serial assessment at 6-month intervals using the same instrument helps track progression and reduces practice effects 1.