Published 15 July 2009, doi:10.1136/bmj.b2831
Cite this as: BMJ 2009;339:b2831

Letters

TYM and Alzheimer’s disease

Age profile?

The first 100% of the full text of this article appears below.

I wondered why Brown and colleagues have incorporated so many young people in their cross sectional control sample (including 18 year old volunteers whose risk of Alzheimer’s disease is infinitesimal).1 The presence of ceiling effects and age effects in the control data means that younger people will be more likely to score at the top of the scale—and the psychometric properties of the test your memory (TYM) test could be unwittingly distorted by the inclusion of so many junior participants.

Older people with presumed Alzheimer’s disease tended to score more highly than younger people. That older controls tended to fare worse than younger people is worrying, although the pairwise statistical comparisons between age-matched controls and suspected Alzheimer’s cases are reassuring. However, cut off scores/centile distributions and receiver operator characteristic curves would be helpful for the age groups at highest risk.

Cite this as: BMJ 2009;339:b2831

Rosaleen A McCarthy, professor and head of neuropsychology1

1 Southampton General Hospital, Southampton SO16 6YD

rosaleen.mccarthy@mac.com

Competing interests: None declared.

  1. Brown J, Pengas G, Dawson K, Brown LA, Clatworthy P. Self administered cognitive screening test (TYM) for detection of Alzheimer’s disease: cross sectional study. BMJ 2009;338:b2030. (9 June.)[CrossRef]

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