Online tests aren't reliable sources for diagnosing the memory-robbing ailment, the Alzheimer's disease, a new study found. Researchers said that these easily accessible online tests failed on various factors including scientific validity, reliability and ethics.

"As many as 80 percent of Internet users, including a growing proportion of older adults, seek health information and diagnoses online," said Julie Robillard, Ph.D., a postdoctoral fellow at the National Core for Neuroethics at the University of British Columbia in Vancouver, British Columbia, Canada.

Alzheimer's disease is an irreversible and progressive brain disease that slowly destroys memory and thinking skills which in turn leads the affected person to be unable to carry out simple tasks essential for daily living. Symptoms of the disease first appear after age 60 in most cases.

According to latest data from the Alzheimer's Association, over 5 million people in the U.S. have AD, a number that is expected to increase to 13. 8 to 16 million people by 2050.

The study was based on 16 popular websites that test AD. Monthly user clicks on these sites ranged from 800 to 8.8 million.

"Self-diagnosis behavior in particular is increasingly popular online, and freely accessible quizzes that call themselves 'tests' for Alzheimer's are available on the Internet. However, little is known about the scientific validity and reliability of these offerings and ethics-related factors including research and commercial conflict of interest, confidentiality and consent. Frankly, what we found online was distressing and potentially harmful," Robillard added in a news release.

The tests were evaluated by a team of geriatricians, human-computer interaction specialists, neuropsychologists and neuroethicists. Specifically, they looked at the scientific validity and reliability of these tests along with other ethical factors. The tests were then given scores from 1 (very poor) to 10 (excellent).

Researchers found that all the sites scored poor or very poor on ethical factors. These sites didn't have good privacy policies, hadn't disclosed commercial interest and failed to word the test outcome in an ethical manner. Also, about 10 of the 16 tests got a "fair" score for human-computer interface appropriate for older audience.

The study findings were announced at the Alzheimer's Association International Conference® 2013 (AAIC® 2013) in Boston.