Improving Alzheimer's screening

A challenge for Alzheimer's treatment is to spot the illness early in its development when future interventions will likely be most effective. Biomarkers have been developed but these are expensive, time-consuming and invasive. Now a team led by James Galvin at Washington University has reported that a new, brief screening tool called AD8, completed by a patient's close relative or friend, is more sensitive than the widely used Mini Mental State Examination (MMSE).

Two hundred and fifty-seven participants (average age 75 years) were assessed with the AD8, the MMSE, an episodic memory test, and with brain-scan and lumbar puncture-based biomarker tests. Using the biomarkers as a gold-standard diagnostic benchmark, Galvin's team found that the AD8 correctly identified 73 of the 78 participants with Alzheimer's disease whilst wrongly identifying 25 participants as having the illness. In stark contrast, the MMSE missed 74 of the 78 participants with Alzheimer's, although it only produced one false positive case. As well as correlating with bio-markers for Alzheimer's, AD8 scores also correlated with performance on a lab test of episodic memory.

The advantage of the AD8 is that it allows the friend or relative to take into account a patient's historical abilities and behaviour, whereas the MMSE only provides a snapshot in time. The AD8 also doesn't depend on patients having insight into their own problems. The AD8 questionnaire comprises eight items including 'Has the person forgotten which month or year it is?' and 'Does he/she forget appointments more frequently than before?'. A score of two or above is a positive result, justifying more in-depth investigation.

Writing in the journal Brain, Galvin and his colleagues said: 'Expert centres have little difficulty in diagnosing Alzheimer's disease, but in the community, diagnoses may be delayed because of an inability to effectively detect cognitive impairment in the setting of a busy office practice. The use of a brief test such as the AD8 may improve strategies for detecting dementia in the community and in developing countries where biomarkers may not be readily available, and may enhance and enrich clinical trial recruitment by increasing the likelihood that participants have underlying biomarker abnormalities that are increasingly becoming required for inclusion.'

--Christian Jarrett