Intended for healthcare professionals


Self administered cognitive screening test (TYM) for detection of Alzheimer’s disease: cross sectional study

BMJ 2009; 338 doi: (Published 10 June 2009) Cite this as: BMJ 2009;338:b2030

Re: TYM test: too many false positives

Regarding Prof. Black's calculation of 11 false positives for every
correct diagnosis of Alzheimer's disease: many screening tests, such as
mammography, have been criticized for producing too many false positives
that generate worry and unnecessary intervention.

One can only imagine the anguish a false diagnosis of Alzheimer's
disease would generate. It is disturbing that this information--which must
surely be considered in implementation of the test, as well as patient
counseling--was not included in the study itself, but owes it reporting to
Prof. Black.

The fact that it takes only 5 minutes and a pencil to produce such
worrisome results is even more disheartening. At least with mammography,
time, cost, availability, and risk are factored into its use.

I would strongly urge that anyone taking the test, or their
caretaker, be required to read and sign a statement indicating they
understand that 11 people are falsely diagnosed with Alzheimer's for every
person correctly identified. In other words, the potential for good news,
even with a "bad" result, vastly outweighs the probability for genuine bad

I would also recommend that there be a clear list of other tests that
will or can be done to more accurately diagnose Alzheimer's, particularly
at an early stage, and that no action be taken in terms of treating,
counselling for care, or anything else until a more accurate diagnosis is

This is particularly important in nursing homes, where such screening
may become widespread and patients with reversible problems may simply be
lumped into the "Alzheimer's group."

Competing interests:
None declared

Competing interests: No competing interests

15 June 2009
Joan McClusky
Medical writer
New York, NY 10003