This section focuses on three groups of medications used to manage Alzheimer's dementia:
- cholinesterase inhibitors
- NMDA-receptor antagonist memantine
- medications used to treat risk factors and behavioural and mental health challenges associated with dementia
Table 10.2: Medications for the treatment of dementia summarizes information about dose, indications and side-effects.
In Canada, three cholinesterase inhibitors (known as acetylcholinesterase inhibitors) are available:
- donepezil (Aricept)
- rivastigmine (Exelon)
- galantamine (Reminyl)
All three of these medications are approved for the treatment of mild to moderate Alzheimer's dementia. Donepezil is approved for severe Alzheimer's dementia. All have equal efficacy in treating dementia.
Facts about cholinesterase inhibitors
- The target for cholinesterase inhibitors is to slow the rate of decline.
- All cholinesterase inhibitors can cause similar side-effects.
- Consider behavioural and functional outcomes in addition to cognitive scores in evaluating the effects of cholinesterase inhibitors.
- Cholinesterase inhibitors may be of benefit in vascular dementia, mixed vascular and Alzheimer's dementia, dementia with Lewy bodies, and dementia associated with Parkinson's disease.
- Cholinesterase inhibitors should not be used in frontotemporal dementia because they may worsen symptoms.
Clinical improvements noted with cholinesterase inhibitors
- Modest improvements are noted in cognition and functioning with cholines-terase inhibitors.
- Most patients return to pretreatment baseline levels of dementia after six to 12 months of treatment.
- Most evidence is for the treatment of mild to moderate stages of dementia with emerging evidence to support the use of cholinesterase inhibitors in advanced stages of dementia.
- This newer medication targets NMDA receptors (glutamate) and reduces neurotoxicity accompanying Alzheimer's dementia.
- Most studies have evaluated the effects of memantine as an adjunct to treatment with cholinesterase inhibitors.
- Memantine is approved for treatment of moderate to severe dementia.
- It tends to be well tolerated. Typical side-effects may include confusion, dizziness and nausea.
- Dose adjustment is required in renal failure.
- Memantine is not covered under most public prescription plans.
- ASA: not indicated for dementia but is used in treatment of comorbid cardiovascular or cerebrovascular disease
- Statins: no consistent evidence that they modify dementia risk in absence of other indications for their use
- Vitamin E: not recommended at present
- Estrogen: not recommended
- No natural products have been demonstrated to have effects on Alzheimer's dementia.
General principles of pharmacotherapy in dementia
When treating a patient with dementia with pharmacotherapy, follow these tips:
- Start low and go slow.
- Use one medication at a time.
- Use medications at optimal dose and duration prior to switching or discontinuing.
- Use medications that will not worsen cognition.
- Be aware of drug–drug interactions.
As dementia progresses, certain behaviours may no longer be problematic and medications may be discontinued gradually after several consecutive months of behavioural stability.
Health promotion and preventing disability
- Identify and treat cardiovascular risk factors and optimize cardiovascular health. This is critical not only in vascular dementia but also in Alzheimer's and other dementias.
- Encourage the patient to keep active in mind and body.
- Educate the patient and caregiver about early signs of delirium and common changes, including psychosis and depression.
Recommendations on screening for cognitive impairment in older adults (Canadian Task Force on Preventative Health, 2015)