What are the diagnostic criteria and treatment options for an elderly patient with suspected dementia, presenting with cognitive decline and memory loss?

Diagnosis of Dementia

Core Diagnostic Criteria

Dementia is diagnosed when cognitive or behavioral symptoms interfere with the ability to function at work or usual activities, represent a decline from previous functioning, are not explained by delirium or major psychiatric disorder, and involve impairment in at least two of five cognitive domains: memory, executive function, visuospatial abilities, language, or personality/behavior changes. 1, 2, 3

The diagnosis requires three mandatory elements 3:

• Functional impairment that interferes with work or daily activities
• Documented decline from previous levels of performance
• Exclusion of delirium or major psychiatric disorder as the primary cause

Diagnostic Assessment Algorithm

Step 1: Obtain History from Patient AND Informant

Informant report is mandatory because patients often lack insight into their cognitive, functional, and behavioral changes. 2 Interview both separately if needed, as disagreement between patient and informant perspectives is itself diagnostically valuable 1.

Focus on specific examples rather than vague terms like "memory loss," which patients may use to describe word-finding difficulty, inattention, or disorientation 1. Document:

• Onset pattern: insidious versus acute 1
• Progression: episodic versus continuous, frequency, duration, intensity 1
• Functional impact: instrumental activities of daily living (managing finances, medications, appointments, household tasks) 1, 4
• Warning signs: missed appointments, showing up at wrong times, victimization by financial scams, new-onset late-life depression or anxiety 1, 4

Use standardized informant questionnaires: ECog, AD8, IQCODE, or Quick Dementia Rating System (QDRS) 2.

Step 2: Objective Cognitive Testing

Use the Montreal Cognitive Assessment (MoCA) rather than MMSE for comprehensive screening, as MoCA has better sensitivity and specificity for identifying mild cognitive impairment and mild Alzheimer disease. 1, 2 For rapid screening in primary care, use Mini-Cog, Memory Impairment Screen + Clock Drawing Test, or Four-item MoCA 2, 4.

Critical pitfall: MMSE has limitations and should not be relied upon exclusively 2. The cognitive assessment must evaluate all five domains: memory (learning and recalling new information), executive function (reasoning, judgment, complex tasks), visuospatial abilities (recognizing faces/objects, spatial orientation), language (word-finding, speech, writing), and personality/behavior changes (apathy, disinhibition, mood fluctuations) 1.

Step 3: Physical and Neurological Examination

Identify focal neurologic abnormalities suggesting stroke, parkinsonism suggesting Lewy body dementia or Parkinson disease dementia, or other signs pointing to specific etiologies 5, 6.

Step 4: Laboratory Testing for Reversible Causes

Perform targeted workup 4, 7:

• Complete blood count with differential
• Comprehensive metabolic panel (especially sodium, calcium, glucose)
• Thyroid function tests (TSH, free T4)
• Vitamin B12, folate, and homocysteine levels

These tests identify hypothyroidism, metabolic encephalopathies (hyponatremia, hyperparathyroidism, hypoglycemia), and nutritional deficiencies that can cause or exacerbate cognitive impairment 7.

Step 5: Comprehensive Medication Review

Compile a complete medication list and identify anticholinergic medications, potentially inappropriate medications, and drug interactions that may contribute to cognitive symptoms. 4 Drug-induced dementia accounts for approximately 9.5% of cases 7.

Step 6: Structural Neuroimaging

Obtain MRI (preferred) or CT when there is recent onset of cognitive symptoms, unexpected decline, recent significant head trauma, or unexplained neurological manifestations. 4 Imaging identifies structural changes including focal atrophy patterns, infarcts, tumors, and normal pressure hydrocephalus 1, 5.

Step 7: Advanced Testing When Indicated

If diagnostic uncertainty persists after initial workup, refer to a dementia specialist for consideration of: 1

• FDG-PET or CSF biomarkers (Aβ42, tau, p-tau) for intermediate certainty
• Amyloid PET according to appropriate use criteria for highest certainty regarding cerebral amyloid pathology
• Genetic testing with genetic counselor involvement if autosomal dominant family history suggests familial Alzheimer disease

Neuropsychological testing should be performed when routine history and bedside examination cannot provide confident diagnosis 1, 5.

Distinguishing Dementia from Mild Cognitive Impairment

The key distinction is functional independence: MCI preserves independence in instrumental activities of daily living, while dementia interferes with ability to function at work or usual activities. 1, 2, 3 Both involve cognitive decline documented by patient/informant report and objective testing, but only dementia crosses the threshold of functional impairment 1.

Common Diagnostic Pitfalls to Avoid

• Do not rely solely on patient self-report without informant corroboration 2
• Do not assume memory impairment is always the primary deficit—nonamnestic presentations occur, particularly with onset before age 65, including language-predominant, visuospatial-predominant, or executive dysfunction-predominant presentations 3, 6
• Do not attribute cognitive changes to "normal aging" without thorough evaluation 1
• Do not overlook psychiatric symptoms as potential presenting features of dementia rather than primary psychiatric disorders—more than half of patients who develop dementia have depression or irritability before cognitive impairment becomes apparent 1, 3

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Treatment of Dementia

Non-Pharmacologic Interventions (First-Line)

Non-pharmacological interventions should take precedence over pharmacotherapy interventions, particularly for behavioral and psychological symptoms of dementia. 1

Implement the following evidence-based approaches 1, 5:

• Cognitive training and activities: reading, playing chess or card games, music therapy, art therapy, reminiscence therapy
• Physical exercise: aerobic exercise (walking, swimming) and anaerobic exercise (weightlifting)
• Dietary modifications: Mediterranean diet with brain-healthy foods (nuts, berries, green leafy vegetables, fish)
• Social engagement: family gatherings and structured social activities

These interventions may have positive impact on cognition and physical function 1.

Pharmacologic Treatment

For Alzheimer Disease

For mild to moderate Alzheimer disease, initiate a cholinesterase inhibitor: donepezil, galantamine, or rivastigmine. 1, 8, 9 These medications provide modest symptomatic relief, delay clinical decline, benefit cognitive function, and help reduce symptoms such as memory loss and confusion 1, 5.

For moderate to severe Alzheimer disease, use memantine (10 mg twice daily after titration from 5 mg once daily). 1, 8 Memantine demonstrated statistically significant superiority over placebo in two randomized controlled trials, with mean differences of 3.4 units on ADCS-ADL functional scale and 5.7 units on SIB cognitive scale at 28 weeks 8.

For moderate to severe Alzheimer disease already on a cholinesterase inhibitor, add memantine to the existing regimen. 1, 8 The combination of memantine and donepezil is recommended in the US, China, and Japan (though not in UK guidelines) 1. In a 24-week trial of patients already on stable donepezil, adding memantine produced statistically significant improvements in both cognition and function compared to placebo 8.

For Parkinson Disease Dementia

For mild to moderate Parkinson disease dementia, use rivastigmine. 9, 5 In a 24-week randomized controlled trial, rivastigmine (3-12 mg/day in divided doses) produced a mean difference of 3.8 points on ADAS-cog and 0.5 points on ADCS-CGIC compared to placebo, both statistically significant 9.

For Vascular Cognitive Impairment

Memantine may be considered for treatment of vascular cognitive impairment in selected patients. 1

Monitoring and Reassessment

Cognitive, functional, neuropsychiatric, and behavioral symptoms need to be periodically reassessed during medication use to monitor disease progression and make adjustments. 1 These medications do not cure the disease but can delay clinical decline 1.

Important Treatment Considerations

In patients aged 80 or older, more than one cause of dementia is often present (e.g., Alzheimer disease plus vascular dementia), requiring consideration of multiple pathologies when planning treatment. 6 The overall goal is to delay progression and manage symptoms to optimize quality of life 1.