Should I be Screened for Alzheimer's?

Should older adults should be screened for Alzheimer's and if they were, what would the benefits be?

Screening is a common approach to the identification of diseases and disorders. Screening takes many forms and routinely includes measures of blood pressure, x-rays, tests for diabetes, cervical cancer and so on. A screening test is a health service provided to identify those individuals who are more likely to be helped than harmed by further tests or treatment to reduce the risk of a disease or its complications.

At face value screening seems a pretty good idea. After all, screening can reduce the risk of developing a condition or its complications and effective screening has the potential to save lives or improve quality of life. But screening tests are not without their problems. In some circumstances, screening can reduce the risk of developing a condition or its complications but it cannot offer a guarantee of protection. In any screening program there is the chance of an incorrect result in which the person is wrongly informed they have a problem (a false positive) or wrongly informed they are fine (a false negative). The emotional upheaval and the possible implications for treatment that a false result may cause are just two of the many ethical dilemmas that result from screening programs. It is therefore important to have a realistic expectation of what any screening program can offer. A screening test is not a diagnostic test, although it may later lead to diagnosis. The purpose of a screening test is simply to identify whether a disease or disorder exists or is likely to occur.

Writing in Alzheimer's & Dementia, Dr.J.Wesson Ashford and colleagues, points out that the current position between different health organizations tends to stop short of recommending screening for dementia; the trend being towards reacting to existing problems rather than predicting their occurrence. So while policy statements encourage physicians to be sensitive to the evidence of cognitive impairment no method is proposed as to how physicians are meant to develop this sensitivity before dementia becomes fairly obvious. As Ashford argues, “waiting to initiate dementia assessment until after dementia is suspected [delays] diagnosis and symptomatic treatment”.

As the biggest risk factor for Alzheimer's disease is age, followed by family history, genotype and certain medical conditions, Dr Ashford suggests yearly screening should be undertaken from the age of 75 but that a few patients may be considered from about the age of 50 on a case-by-case basis. Yet, as Ashford concedes, the sensitivity of screening tests is still under some debate, particularly in the area where transitions from normal function, through mild cognitive impairment, to dementia are occurring.

So, should older adults be routinely screened for Alzheimer’s? It seems the jury is out. Advocates for routine screening, such as Dr Ashford and colleagues, compete against the more consistent view of health organisations. One such example is the U.S. Preventive Services Task Force who say that the evidence is insufficient to recommend for or against routine screening for dementia in older adults. In its review of screening for dementia the Task Force found:

Good evidence that some screening tests can successfully detect dementia. However, age and education of the patient affect the accuracy and interpretation of some tests, producing misleading results.

Medications such as cholinesterase inhibitors can slow the rate of decline in cognitive function, but the evidence of their ability to improve key activities of daily life is less clear.

The evidence is insufficient to determine whether the benefits observed in drug trials conducted in specialized neurological clinics can be generalized to patients in primary care settings.

No data are available to assess the potential harms of dementia screening, such as social stigma, depression, and anxiety.

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Source:
Ashford, J.Wesson. Borson, Soo. O'Hara, Ruth. Dash, Paul. "Should older adults be screened for dementia?." Alzheimer's & Dementia 2(2006): 76-85.

"Task Force Report Neutral on Routine Screening for Alzheimer's." SNM advancing molecular imaging & therapy. 04 June 2003. 11 Dec 2006 <http://interactive.snm.org/index.cfm?PageID=541&RPID=535&gt;.

"What is Screening?." UK National Screening Committee. Dept of Health. 10 Dec 2006 <http://www.nsc.nhs.uk/whatscreening/whatscreen_ind.htm>.