Diagnostic Workup for Suspected Dementia or Alzheimer's Disease
A comprehensive diagnostic evaluation for suspected dementia should include a structured history, cognitive assessment, physical examination, laboratory testing, and brain imaging, followed by appropriate specialist referral for complex cases.
Initial Assessment
History Taking
- Obtain detailed history of cognitive symptoms from both patient and reliable informant (family member/caregiver) 1, 2
- Document specific examples of:
- Memory difficulties (especially learning and recalling new information)
- Changes in language abilities
- Executive function problems (planning, organizing)
- Visuospatial difficulties
- Behavioral or personality changes
- Establish timeline of symptom onset and progression 1
- Assess impact on daily functioning and independence 1, 3
Cognitive Assessment
- Administer validated cognitive screening tools:
- Document baseline scores for future comparison 2
- Consider educational level when interpreting results 2
Physical and Neurological Examination
- Perform thorough neurological examination to identify:
- Focal neurological signs (suggesting stroke or other structural lesions)
- Extrapyramidal signs (suggesting Lewy body dementia or Parkinson's disease)
- Gait abnormalities 1
Laboratory Testing
First-Tier Laboratory Tests (Essential)
- Complete blood count
- Comprehensive metabolic panel (including electrolytes, glucose, renal and liver function)
- Thyroid function tests (TSH)
- Vitamin B12 and folate levels
- Homocysteine level 1, 2, 4
Second-Tier Laboratory Tests (Based on Clinical Suspicion)
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
- Syphilis serology (RPR/FTA-ABS)
- HIV testing
- Lyme disease antibodies
- Antinuclear antibodies
- Thyroid peroxidase antibodies (if autoimmune encephalopathy suspected) 1
Neuroimaging
Brain MRI (Preferred) or CT if MRI Contraindicated
- Assess for:
Specialist Referral
When to Refer to a Specialist
- Atypical cognitive presentations (aphasia, apraxia, agnosia)
- Sensorimotor dysfunction
- Severe mood/behavioral disturbances
- Rapid progression or fluctuating course
- Early age of onset (< 65 years)
- Incongruent history and examination findings
- Normal office-based cognitive testing despite concerning symptoms 1
Specialist Evaluation May Include
- Detailed neurobehavioral assessment
- Neuropsychological testing (when office-based assessment is insufficient) 1, 2
- Advanced diagnostic tests:
Diagnostic Disclosure
- Communicate findings honestly and compassionately to both patient and care partner 1
- Provide information about:
- Name and characteristics of the cognitive syndrome
- Likely underlying disease(s)
- Disease stage
- Expected progression
- Treatment options
- Safety concerns
- Available resources for education and support 1
Common Pitfalls to Avoid
Attributing cognitive changes to "normal aging" - Cognitive decline that interferes with daily function is never normal aging 1, 3
Missing treatable causes - Hypothyroidism, vitamin deficiencies, medication effects, and metabolic disorders can cause reversible cognitive impairment 4
Overlooking depression - Pseudodementia due to depression can mimic dementia but is treatable 3, 5
Inadequate cognitive testing - Brief office assessments may miss mild cognitive impairment; consider formal neuropsychological testing when clinical suspicion remains high despite normal screening 1, 2
Failure to obtain collateral history - Patient self-report alone is insufficient; information from family/caregivers is essential 1
Neglecting impact of medications - Review all medications for potential cognitive side effects; drug toxicity accounts for approximately 9.5% of dementia cases 4
By following this structured approach to evaluation, clinicians can accurately diagnose dementia, identify its underlying cause(s), and develop appropriate management plans to optimize patient outcomes.