How do we refuse Alzheimer's test?
Q - What should we say to those not eligible for Alzheimer's screening?
A - In the absence of mutations in screened genes in a family with early onset disease, it is highly likely that the disease is due to a combination of interacting genetic and environmental factors.
In such cases, close inspection of a family history often does not indicate affected members further than the previous generation, and shows a later (60-70 years old) and variable age at onset. These families frequently demonstrate an association with the e4 allele of the apolipoprotein E gene. This allele is common in the general population, and individuals carrying two of them often live until their 90s without dementia. The
e4 allele is also associated with cardiovascular disease.
In these instances, GPs counselling family members should point out that the cause of dementia is multifactorial and that testing does not have any benefit and is not recommended under current UK guidance.
For families where there is a dementia patient with onset over 65 years of age, a similar viewpoint should be offered, indicating that the disease shows little indication of running in families, and that there are no definitive or helpful genetic tests available.
Dr CM Morris is senior lecturer at the MRC-University of Newcastle
upon Tyne centre for
clinical brain ageing