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How current screening methods miss mild cognitive impairment

Researchers at the University of California San Diego School of Medicine and Veterans Affairs San Diego Healthcare System have found that the screening tools currently used to identify mild cognitive impairment (MCI) often give a false-negative. This means that people who are likely to go on to develop Alzheimer’s may not be getting the timely care that they need.

MCI is classed as a slight but noticeable decline in cognitive abilities. This may be something as simple as forgetting names or being unable to remember a list of items or address. While these changes may not disrupt the patient’s daily life, an MCI diagnosis does indicate that they have an increased risk of going on to develop Alzheimer’s, or some other form of dementia.

The team from San Diego suggest that there is an error rate of over 7% in the existing MCI screening methods. The people who have had a false-negative result from standard screening tools, do receive an MCI diagnosis when subjected to more extensive testing. This means that those people who have been incorrectly diagnosed as cognitively normal are unlikely to receive the medical advice or treatment that they need, including advice to change diet and lifestyle, or to be given referrals to providers of health care.

MCI is currently diagnosed using a range of diagnostic criteria which mainly rely on the person being screened reporting problems with their memory, together with a single test score and clinical judgement. The authors of the study believe that significant errors in diagnosis have occurred by using this approach. Not only have they seen false-negative results, but their previous research also noted a high rate of ‘false-positives’, in that people who were diagnosed with MCI were found not to have it when they underwent further testing. These false-positives accounted for as many as one-third of MCI cases which, when coupled with the 7% of false-negatives, suggest that the current diagnostic criteria is in need of improvement.

The team also believe that these false-negative diagnoses can have a negative impact on research studies of MCI and early Alzheimer’s disease, which has consequences for finding and developing effective treatments and therapies.

This study was published online in a recent edition of the Journal of Alzheimer’s Disease

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