Alzheimer’s disease is often and easily misdiagnosed in the elderly, a new study shows — raising new doubts about existing detection methods for the traumatic, memory-loss illness.Early findings suggest that older people who had their brains examined after death during autopsies had often been incorrectly diagnosed with Alzheimer’s while they were alive.

“This is true of every population of Alzheimer’s patients,” Peter Davies, the director of the Litwin-Zucker Center for Research in Alzheimer’s Disease, told AOL Health. “The diagnosis of Alzheimer’s disease cannot be made with certainty in life. The definitive diagnosis can only be made with autopsy.”

The study looked at the brain autopsies of 426 Japanese-American men who’d lived in Hawaii and died at age 87 on average. Of that population, 211 had been told they had dementia when they were alive, and most of the diagnoses blamed the condition on Alzheimer’s disease.

The study is troubling because there are several other causes of dementia in the elderly, including depression, overmedication, thyroid problems, vitamin B-12 deficiency and vascular disease, which can cause mini strokes and block blood flow to the brain. Typically, those kinds of dementia are more easily treated than Alzheimer’s.

“There are a dozen common ways to get to a demented state,” Davies said. “A good diagnosis is essential because you don’t know what you’re dealing with without that. You may have something treatable.”

About half of those autopsied for the study were informed that they had the disease while alive, but didn’t have enough brain lesions at death to confirm the diagnosis, according to researchers at Kuakini Medical System in Honolulu.

In that vein, the authors of the paper believe that more trials are in order to minimize the misdiagnoses.

“Larger studies are needed to confirm these findings and provide insight as to how we may more accurately diagnose and prevent Alzheimer’s disease and other principal dementing disease processes in the elderly,” said White.

Most of those who’d been misdiagnosed did have one or a combination of other kinds of brain lesions that would explain the dementia. But their scans didn’t show sufficient evidence for the more serious condition of Alzheimer’s.

The problem, explained Davies, is that many other forms of dementia and memory impairment can appear to be Alzheimer’s to a less experienced practitioner.

“Now Alzheimer’s is such a popular topic, it’s really overdiagnosed,” Davies, a longtime specialist in the disease who practices at North Shore hospital, told AOL Health. “Probably 25 percent of the people in the community diagnosed with Alzheimer’s don’t have it.”

Furthermore, the likelihood of an incorrect diagnosis rose with age, the Hawaiian scientists found.

“Diagnosing specific dementias in people who are very old is complex,” study author Dr. Lon White said in a statement. “With the large increase in dementia cases expected within the next 10 years in the United States, it will be increasingly important to correctly recognize, diagnose, prevent and treat age-related cognitive decline.”

Davies said that Alzheimer’s comes with a very specific set of symptoms and behaviors, including severe memory loss, an inability to process thought fully and an impairment in intellectual functioning. The impact on memory and thinking goes way beyond everyday forgetfulness and haziness, he said.

“Alzheimer’s is not just a memory disorder. It affects the ability to think things through,” he said. “This is a serious inability to learn new information — serious enough to really impair your job or your social life.”

The research, funded by the National Institute on Aging and the Department of Veterans Affairs, will be presented at the American Academy of Neurology’s annual meeting in April.

Catherine Donaldson-Evans