If there were an early medical test for Alzheimer’s disease (AD), would you choose to take it? Most adults would, suggests a study in the open access journal Alzheimer’s Research & Therapy. The potential repercussions of this could be high, with medical, political and legal ramifications.

Alzheimer’s disease is the most common type of dementia, a chronic, neurodegenerative disease without a cure. Early detection, before symptoms have set in, could broaden the window for therapeutic intervention, and current attempts to devise reliable, predictive tests appear promising.

Elizabeth Wikler and colleagues have conducted the first large, international, randomized public survey of interest in the possibility of early medical testing for AD. More than 2,500 randomly-selected adults from the United States, France, Germany, Poland and Spain were surveyed for their opinions.

Two thirds of those asked said they were “somewhat” or “very likely” to take an early test. Interest was higher among those worried about developing the disease, those with a family history of AD, and those who had been caregivers for AD patients.  Interest also varied by country, with the highest levels of interest found in Poland and Spain, and the lowest in Germany.

Interestingly, knowing the disease was fatal did not significantly predict interest in testing; however, among those who have a blood relative with the disease and are therefore at higher risk of the disease, interest in testing was higher in groups who knew the disease was fatal.

Lastly, in the United States, controlling for levels of perceived risk and other demographic factors, levels of interest in AD testing among African-American (41.3%) and Hispanic (35.3%) respondents were significantly higher than those reported for whites (23.1%).

But if such a test becomes reality, and demand matches interest, millions of people will become members of a new population and political advocacy group: asymptomatic adults living with the diagnosis of AD.

In the clinical world, diagnosed asymptomatic individuals might be more likely to press for follow-up tests, continued evaluation, and medical management of Alzheimer’s related complications. The related costs could strain already-overburdened health systems, the authors say. Meanwhile, in the legal realm, early testing raises issues relating to confidentiality, employment, insurance, disclosure and discrimination, to name but a few. If not addressed properly, any of these issues could pose real barriers to test participation.

Currently, early medical testing for AD is available primarily in research settings, offering patients a probabilistic measure of their risk for the disease by analyzing their apolipoprotein E (ApoE) genotype. However, this test is neither necessary nor sufficient for the diagnosis of the disease, and therefore, has not been recommended for broad clinical use. Other tests focusing on genetic mutations associated with early-onset AD, a subtype of the disease, have had more success in predicting the presence of the disease. Therefore, alternative testing methods for AD, based on molecular, cellular and larger structural changes, are the focus of much current research.

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