The Fox, the Pigeon and the Cognitive Test

Yamaguchi and colleagues have devised a simple test for screening for dementia and report their results in a paper which is freely available here.  They recruit 160 older adults from outpatient clinics (presumably neurology clinics) and exclude people with delirium as well as specific neurological conditions. They then present them with a test. The examiner fold their hands into two shapes – one resembling a fox and the other a pigeon. The researchers intend that these are meaningless and that they place a demand on the parietal lobe. They further argue that in the prodromal phase of Alzheimer’s Disease, parietal lobe dysfunction can precede the symptomatic phase of the illness. Within their group they have both subjects with dementia and mild cognitive impairment and use the Clinical Dementia Rating to stratify according to severity. The fox shape is easier to reproduce than the pigeon shape.  More than 50% of subjects with a CDR of greater than 0.5 failed to reproduce the pigeon shape.

Overall the specificity of the test was 94% with the following sensitivities

– 58% in CDR 0.5

– 77% in CDR 1

– 75% in CDR 2

– 90% in CDR 3 correlating with severe dementia

While these initial test results are promising it would be useful to have replication studies to examine the interaction with different variables, norming results amongst the population and correlating results with progression to dementia subtypes. Subsequent integration into clinical practice would require careful consideration, contingent upon local protocols as well as an understanding of expectations from the test.

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