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Alzheimer Society in partnership with leading Canadian Alzheimer clinicians and researchers
Population Screening for Dementia – Position Statement
Date: August 2008
Position: At this time, based on direction from Canada's leading Alzheimer Clinicians and Researchers, as well as the conclusions of evidence-based task forces in Canada, the US and the UK, the Alzheimer Society does not support population-based screening for memory and cognitive problems, regardless of whether these screenings take place in a primary care setting, a pharmacy or other non-clinical public locations.
Diagnosing dementia is a complex and difficult process. There is no single test that can tell that someone has or does not have Alzheimer's or a related disease. Making a diagnosis of dementia takes the time and expertise of skilled practitioners because the diagnosis can only be made after a systematic assessment that takes into account other possible causes for the symptoms (including conditions such as depression, thyroid or heart disease, infections, drug interactions or alcohol abuse).
The diagnostic process therefore requires a careful history of the symptoms, physical, neurological and mental status examinations, psychiatric and psychological evaluations, laboratory tests, and where applicable imaging of the brain. Information from relatives or caregivers is also required.
As concern about Alzheimer's increases, some have argued that population-based screening (also referred to as broad screening) should be offered for dementia. Screening is a process by which individuals who have no symptoms or other indication of a specific disease are checked to determine whether they might have signs of that disease. Screening should be undertaken only when there is clear evidence that early treatment of the condition results in more good than harm. (Examples of effective screening programs include testing for high blood pressure and certain cancers.)
At this time, based on direction from Canada's leading Alzheimer Clinicians and Researchers, as well as the conclusions of evidence-based task forces in Canada, the US and the UK, the Alzheimer Society does not support population-based screening for memory or cognitive problems, regardless of whether these screenings take place in a primary care setting, a pharmacy or other non-clinical public location.
The Alzheimer Society continues to promote the early detection of dementia, thereby allowing people with the disease and their families to make key financial and care decisions while they are still functioning at the highest possible level. However, the Society will not advocate for population-based screening until there is evidence that there are effective and validated screening tools and that the benefits outweigh any potential harm.
The Alzheimer Society's position is based on the following concerns:
- Level of accuracy of current diagnostic tools: Used in isolation from clinical settings and in the absence of other critical examinations and tests, there is a disturbing lack of accuracy inherent to using mass screening diagnostic tools currently available. There is evidence that as many as 15 to 20 per cent of normal individuals will be falsely labeled as having a problem (i.e. false positive). An equivalent number of individuals with true cognitive problems may identified as normal (i.e. false negatives).
- False positives: Receiving a diagnosis of dementia can trigger a number of strong emotional responses including anger, anxiety, despair and depression. Delivering a diganosis of Alzheimer's therefore requires appropriate settings to ensure information and support. There is a great potential for harm in cases of ‘false positive', with possibly grave consequences from an emotional health and practical stand point (for e.g. in some jurisdictions, a diagnosis for Alzheimer's may cause denial of health insurance, may affect an individual's right to drive, etc.) Furthermore, population-based screening does not lend itself well to such patient care quality requirements.
- False negatives: Although being diagnosed with dementia can be an upsetting experience, it can also be a relief because knowing the causes of the problems can resolve the anxiety felt by both the person affected and their family. Receiving an early diagnosis allows a person to gain access to information, resources and support, to benefit from treatments, to maximise quality of life, to plan for the future, and to develop and engage support networks. There is therefore great potential for harm in cases of ‘false negatives' in that people may develop a false sense of relief, which may delay obtaining a correct diagnosis, time-sensitive access to treatments and opportunities for financial and care planning.
- Social and economic impact: The outcome of population-based screening can be an unplanned burden on the health care system without offsetting benefit. While earlier diagnosis is desirable, incorrect screening results (both false positive and false negative) can inappropriately influence the use of health care resources (e.g., family physicians and community services), as well as undermine legitimate early diagnosis programs.
Research to develop and validate reliable early screening tools continues, and eventually we may be able to screen appropriately for Alzheimer's disease in the general population. The validation of a screening program requires well designed randomized controlled trials and the comparison between current medical diagnoses with a formal screening program with a large enough number of people to be certain that the screening program is accurate. For the present, no screening tool has the accuracy of the current medical diagnosis. Pressures to institute screening programs with unproven accuracy and benefit could divert much-needed resources from the health and social care systems and have overall negative consequences for care of patients with dementia and other illnesses. 1
The Alzheimer Society continues to recommend that people who are concerned about their memory and cognitive health see their family physician. Those who do not have a family doctor should contact their local Alzheimer Society to learn more about the disease, and how to find resources for appropriate diagnosis, treatment and care within their community. For more information, please visit www.alzheimer.ca.
Endnote
1. Dementia Screening in Primary Care Is It Time? JAMA, November 28, 2007—Vol 298, No. 20
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