What is the approach to diagnosing and managing dementia?

Diagnosing Dementia: A Structured Clinical Approach

Dementia diagnosis requires obtaining corroborative history from a reliable informant combined with standardized cognitive assessment, basic laboratory testing to exclude reversible causes, and neuroimaging in most cases—this multi-domain evaluation establishes both the presence of dementia and guides subtype classification. 1, 2

Step 1: Essential History and Informant Assessment

Obtaining corroborative history from a reliable informant is mandatory and has prognostic significance—never rely solely on patient self-report as patients with dementia lack insight into their deficits. 1, 3, 4

Document the following specific domains:

• Cognitive changes: Memory problems, language difficulties, executive dysfunction, visuospatial impairment, personality changes 2, 3
• Functional decline in IADLs: Ability to manage finances, medication management, transportation, household management, cooking, shopping 3, 4
• Behavioral symptoms: New onset versus longstanding neuropsychiatric symptoms 1
• Onset and progression pattern: Gradual onset over years suggests neurodegenerative disease; rapid onset suggests vascular or acute causes 3
• Risk factors: Family history, vascular risk factors, prior head trauma, stroke/TIA, depression, sleep apnea, head injury 2, 4
• Medication review: Identify drugs causing cognitive impairment 2, 3

Use structured informant-based tools: AD8, IQCODE, ECog for cognitive/functional changes; Lawton IADL Scale for functional assessment; NPI-Q or MBI-C for behavioral symptoms. 1, 3, 4

Step 2: Cognitive Screening with Validated Tools

The MoCA is more sensitive than MMSE for detecting mild cognitive impairment and early dementia, while MMSE remains valuable for moderate dementia and longitudinal tracking. 1, 2

• MoCA: Superior sensitivity and specificity for identifying MCI and mild AD 1
• MMSE: Sensitivity and specificity >80% for distinguishing dementia; validated in clinical trials for longitudinal tracking 1, 3, 4
• Clock Drawing Test: Useful supplement for visuospatial and executive function screening 1, 3

Critical pitfall: Diagnosis should never be based solely on impaired cognitive screening test results—integrate with history, functional assessment, and informant report. 1

Step 3: Core Laboratory Testing (Mandatory)

Perform these tests on all patients to exclude reversible causes: 2, 3, 5

• Complete blood count
• Comprehensive metabolic panel
• Thyroid function tests (TSH, free T4)
• Vitamin B12 level
• Folate level
• HIV testing if risk factors present 1, 3
• Syphilis serology if clinically indicated 2

Step 4: Neuroimaging—When and What Type

MRI is preferred over CT, especially for detecting vascular lesions, atrophy patterns, and structural abnormalities. 2, 3

Anatomical neuroimaging is recommended when: 2, 3

• Onset of cognitive symptoms within past 2 years
• Unexpected and unexplained decline in cognition/function
• Recent significant head trauma
• Unexplained neurological manifestations
• History of cancer
• Risk for intracranial bleeding
• Symptoms compatible with normal pressure hydrocephalus
• Significant vascular risk factors

Recommended MRI sequences: 3D T1 volumetric, FLAIR, T2 (or susceptibility-weighted imaging), diffusion-weighted imaging 3

Step 5: Diagnostic Formulation

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. 2, 4

Determine dementia subtype based on clinical features: 1

• Alzheimer's disease (50-70% of cases): Gradual onset, prominent memory impairment 1
• Vascular dementia: Stepwise decline, focal neurologic signs, vascular risk factors 1
• Dementia with Lewy bodies (DLB): Visual hallucinations, parkinsonism, fluctuating cognition 1
• Frontotemporal dementia (FTLD): Behavioral changes, language impairment, younger onset 1
• Parkinson disease dementia (PDD): Motor symptoms precede cognitive decline 1

Step 6: Rule Out Mimics and Contributors

Systematically evaluate for conditions that can mimic or contribute to dementia: 2, 4

• Depression (use GDS or PHQ-9) 1, 3
• Delirium
• Metabolic disturbances
• Medication effects
• Sleep disorders (particularly sleep apnea) 4
• Sensory deficits (hearing loss, vision loss) 4

Common pitfall: Failing to assess for depression and sleep disorders leads to missed treatable contributors to cognitive impairment. 4

Step 7: Severity Assessment

Base severity on three dimensions: 4

• Degree of cognitive impairment: Use MMSE or MoCA scores
• Level of functional impairment: Use ADCS-ADL or FAQ
• Behavioral symptom severity: Use NPI-Q

Mild cognitive impairment versus dementia: The distinction rests on whether there is significant interference with daily functioning—MCI patients maintain independence in IADLs. 4

Management Framework After Diagnosis

Pharmacologic Treatment by Severity

For mild to moderate Alzheimer's disease: Cholinesterase inhibitors (donepezil, galantamine, rivastigmine) are recommended—these delay clinical decline and benefit cognitive function. 1, 6

For moderate to severe Alzheimer's disease: Memantine is recommended, either alone or combined with donepezil. 1, 7

For severe Alzheimer's disease: The combination of memantine and donepezil is recommended (except in UK guidelines). 1

For Parkinson disease dementia: Rivastigmine can be used for symptomatic treatment. 5

Non-Pharmacologic Interventions (Priority for BPSD)

Non-pharmacologic interventions should take precedence over pharmacotherapy for behavioral and psychological symptoms of dementia (BPSD). 1

Recommended interventions include: 1

• Cognitive training and activities (reading, playing chess, puzzles)
• Music or art therapy
• Reminiscence therapy
• Physical exercise: aerobic (walking, swimming) and anaerobic (weightlifting)
• Mediterranean diet or brain-healthy foods (nuts, berries, green leafy vegetables, fish)

Limitation: Patients with moderate to severe dementia may have difficulty engaging in cognitive activities and should have limited physical demands. 1

Longitudinal Monitoring Protocol

Schedule follow-up visits every 6-12 months for stable patients to track disease progression using a multi-dimensional approach. 2, 3, 4

Assess all four domains at least annually: 3, 4

• Cognition: Use MMSE for longitudinal tracking 3, 4
• Functional autonomy: Use ADCS-ADL or FAQ 3, 4
• Behavioral symptoms: Use NPI-Q (more frequent assessment if symptoms present) 3, 4
• Caregiver burden: Use Zarit Burden Interview 3

For patients with subjective cognitive decline but normal testing: If corroborative history is positive, schedule annual follow-ups and consider referral to memory clinic; if negative, provide reassurance and offer follow-up if deterioration occurs. 1, 3