Would it be beneficial to add Namenda (memantine) to the treatment regimen of an elderly female patient with mixed dementia, characterized by both Alzheimer's disease and vascular dementia components, and a St. Louis University Mental Status Exam score of 25/30?

Adding Memantine (Namenda) to Treatment for Mixed Dementia

Yes, adding memantine 20 mg/day is beneficial for this patient with mixed dementia (Alzheimer's and vascular components) and should be initiated, as it provides cognitive, functional, and behavioral benefits for both dementia subtypes while being well-tolerated. 1, 2

Rationale for Memantine in Mixed Dementia

Evidence for Both Dementia Components

For the vascular dementia component:

• Canadian Stroke Best Practice Recommendations support memantine for small but meaningful improvements in cognitive function in vascular dementia, particularly for mild to moderate disease severity 1
• Statistically significant improvements on ADAS-cog scores (2.15 points, 95% CI 1.05 to 3.25) at 28 weeks in mild to moderate vascular dementia 1
• Significant behavioral benefits measured by the Nurses Observation Scale for Geriatric Patients, with notable protective effects against agitation 1

For the Alzheimer's disease component:

• FDA-approved indication for moderate to severe Alzheimer's disease, with demonstrated efficacy on cognition (Severe Impairment Battery), global assessment (CIBIC-plus), and activities of daily living 3, 4
• The American Academy of Neurology supports memantine for significant improvements in cognition, daily functioning, and behavioral symptoms in moderate to severe Alzheimer's disease 4

Optimal Dosing Strategy

Titration schedule per FDA labeling: 3

• Start at 5 mg once daily
• Increase by 5 mg increments weekly: 10 mg/day (5 mg twice daily), then 15 mg/day, then target dose of 20 mg/day (10 mg twice daily)
• The 20 mg/day dose is the evidence-based target for optimal cognitive, behavioral, and functional outcomes 2, 1

Safety and Tolerability Profile

Memantine is well-tolerated with favorable safety: 3, 2

• Discontinuation rates due to adverse effects are similar to placebo (10.1% vs 11.5%) 3
• Common adverse effects include dizziness, headache, confusion, and constipation (generally mild) 3, 1
• Importantly, memantine shows protective effects against agitation compared to placebo 5, 1

Important Clinical Considerations

Renal function assessment is critical: 2, 3

• For severe renal impairment (creatinine clearance 5-29 mL/min), reduce target dose to 10 mg/day (5 mg twice daily) 2, 3
• Standard 20 mg/day dosing is appropriate for normal to moderate renal impairment 2

Combination therapy potential:

• If the patient is already on a cholinesterase inhibitor (donepezil, rivastigmine, or galantamine), memantine can be safely added 4, 3
• Combination therapy with memantine plus cholinesterase inhibitors shows superior outcomes compared to cholinesterase inhibitor monotherapy in moderate to severe Alzheimer's disease 4
• The combination is well-tolerated with no significant increase in serious adverse events 4

Addressing the SLUMS Score of 25/30

This score suggests mild cognitive impairment or mild dementia:

• While FDA approval is specifically for moderate to severe Alzheimer's disease 3, the vascular dementia evidence supports use in mild to moderate disease 1
• Given the mixed dementia presentation, memantine addresses both pathologies simultaneously 1, 2
• The behavioral benefits may be particularly valuable even if cognitive benefits are modest 1, 4

Common Pitfalls to Avoid

Dosing errors: 3

• Do not advance dose too rapidly—maintain one-week intervals between increases to optimize tolerability
• If doses are missed for several days, resume at lower dose and retitrate

Monitoring considerations:

• Conditions that raise urine pH (severe urinary tract infections, renal tubular acidosis) may decrease urinary elimination and increase plasma levels 3
• Continue memantine even with some cognitive decline if neuropsychiatric symptoms (agitation, aggression) show clinically meaningful reduction 4, 2