Drugs for Alzheimer's disease — PBS criteria no longer include referral to a specialist

Drug treatments do not alter the pathology of Alzheimer's disease.² At best, cholinesterase inhibitors (donepezil, galantamine and rivastigmine) or the N-methyl-D-aspartate antagonist (memantine) may result in a temporary and modest improvement in symptoms or delay decline in cognitive function.³ Evidence does not support prescribing these drugs for everyone with Alzheimer's disease — none of the drug treatments is PBS listed for severe dementia, and stabilisation or slowing decline may not be an appropriate goal for people with poor quality of life.⁴

There is insufficient evidence to show that any one drug is more effective than another.⁵ Base choice of drug on⁴:

• patient comorbidities (contraindications to use)
• tolerance
• adverse-effect profile
• ease of use.

Discontinuation due to adverse events (e.g. gastrointestinal symptoms with the cholinesterase inhibitors) is common with these medicines.²

Regardless of drug treatment, individualised management involving family and carers and non-drug treatments, particularly social support, remain important for people with Alzheimer's disease.^2,5

Use either the MMSE or the Standardised Mini-Mental State Examination (SMMSE) to assess a patient's eligibility for PBS subsidy of a cholinesterase inhibitor or memantine. These 30-point scales assess cognitive function, with lower scores indicating poorer function.

The cholinesterase inhibitors are PBS listed for mild to moderate Alzheimer's disease and can only be prescribed for people with an MMSE score of 10 or more (see Table 1).

If a patient's MMSE score is ≥25 points at baseline, also assess their score using the Alzheimer's Disease Assessment Scale – Cognitive subscale (ADAS-Cog), and include both results in the authority application. For people with this mild level of cognitive impairment at baseline, improvement on either scale is sufficient to merit continued treatment at 6 months.

Memantine is PBS listed for moderately severe Alzheimer's disease and can only be prescribed for people with a MMSE score of 10–14, inclusive (see Table 1).

Not everyone with Alzheimer's disease responds to drug treatment and it is not possible to predict those who will (see NPS News 59: Drugs used in dementia in the elderly). Review treatment at 3–6 months, when a beneficial effect is expected. ^4,6 Consider stopping treatment in the event of poor adherence, significant adverse effects or a lack of stabilisation or improvement in symptoms.^4–6 At 6 months, patients need to demonstrate cognitive improvement to qualify for continuing treatment (Table 1).

Table 1.
PBS eligibility criteria for initiating and continuing drug treatment

* Can also be prescribed for people who cannot register a score of ≥ 10 for reasons other than Alzheimer's disease (e.g. learning or sensory disability). See www.pbs.gov.au for full list of these criteria.

ADAS-Cog: Alzheimer's Disease Assessment Scale – Cognitive subscale

Authorised nurse practitioners cannot initiate donepezil, galantamine, rivastigmine or memantine, but can continue them as part of a formal care plan with a medical practitioner (continuing therapy only model). See the PBS website for more information on nurse practitioner PBS prescribing.

The optimal duration of therapy for a cholinesterase inhibitor or memantine has not been established; there is limited evidence of effectiveness with any of the drugs beyond one year.⁴

Review patients regularly to determine if the benefit of treatment outweighs any adverse effects; assess cognitive function (e.g. using the MMSE or General Practitioner Assessment of Cognition test) as well as day-to-day functioning and behaviour.⁵

Refer patients to a specialist when⁷:

• diagnosis is in doubt
• the patient is young
• the presentation is unusual
• the patient or family requests it.