Letters TYM and Alzheimer’s disease

Authors’ reply

BMJ 2009; 339 doi: http://dx.doi.org/10.1136/bmj.b2834 (Published 15 July 2009) Cite this as: BMJ 2009;339:b2834
  1. Jeremy Brown, consultant neurologist1,
  2. George Pengas, clinical research fellow1,
  3. Kate Dawson, research nurse1,
  4. Lucy A Brown, honorary research assistant1,
  5. Philip Clatworthy, clinical research fellow1
  1. 1Department of Neurology, Addenbrooke’s Hospital, Cambridge CB2 2QQ
  1. jmb75{at}medschl.cam.ac.uk

    The test your memory (TYM) test is intended to be self administered by the patient— allowing testing of 10 cognitive skills in minimal operator time—but it needs to be overseen and interpreted by a health professional.1 The test is therefore self administered but not for self diagnosis. It is hard to choose an alternative title which clarifies this without being too long. As a result of the publicity concerning self testing we have delayed the launch of the website tymtest.com until we can ensure easy access for professionals while discouraging self testing.

    The TYM test has been validated in a single study in a single population presenting with cognitive problems, and shows great promise as a screening tool in this setting. Problems would occur with indiscriminate screening of asymptomatic patients, with many false positives. We agree that such testing is not appropriate. A low TYM score suggests the need to look for a cause, it does not mean the patient has Alzheimer’s disease. We agree that the TYM test needs to be validated in other populations. Longitudinal data are crucial and are being collected.

    The TYM test is not a diagnostic test. The diagnosis of Alzheimer’s disease needs a proper clinical assessment from a trained professional. The TYM test is an aid in this process but not a replacement for it. Human beings and brain diseases are inherently variable, and a quick memory test which would allow an untrained person to safely diagnose Alzheimer’s disease or distinguish Alzheimer’s disease from other forms of degenerative or vascular dementia is unlikely ever to exist. An experienced clinician may recognise a pattern of scoring on the TYM which suggests Alzheimer’s disease or semantic dementia in many patients.

    We include a wide age range of controls because many younger patients have cognitive complaints as a result of epilepsy, multiple sclerosis, and other conditions, and we believe the TYM test may be useful in these patients. The average TYM scores of controls are remarkably stable but do fall off after the age of 70, as do most similar tests. There were no significant differences between older and younger patients with Alzheimer’s disease.

    We are well aware of the ethical debate around early diagnosis of Alzheimer’s disease and share many of the concerns of correspondents. Progress towards early diagnosis must be made for several reasons. If a treatment that halts Alzheimer’s disease becomes available, we need a test to identify those likely to benefit.

    Notes

    Cite this as: BMJ 2009;339:b2834

    Footnotes

    • Competing interests: None declared.

    References