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MONDAY, July 23, 2018 (HealthDay News) -- Many older Americans with dementia don't know they have the disease, a new study indicates.

A review of data from 585 Medicare recipients with probable dementia found nearly 6 out of 10 were either undiagnosed or unaware of their diagnosis.

Those who had less than a high school education, who went to medical visits alone and who had fewer problems with daily tasks were more likely to be among the unaware ones. Hispanics were also more likely to have undiagnosed dementia, according to the study.

"There is a huge population out there living with dementia who don't know about it," said study lead author Dr. Halima Amjad. "The implications are potentially profound for health care planning and delivery, patient-physician communication and much more."

Amjad is an assistant professor of medicine at Johns Hopkins University School of Medicine in Baltimore.

"If dementia is less severe and people are better able to perform day-to-day tasks independently, symptoms of cognitive loss are more likely masked, especially for patients who visit the doctor without a family member or friend who may be more aware of the patient's symptoms," she said in a university news release.

About 5.7 million people in the United States have dementia, but only half of them have a formal doctor's diagnosis, according to the Alzheimer's Association.

Early diagnosis is important for maintaining or improving health and for planning care, Amjad said. These findings could help doctors identify which patients may need more careful screening, she added.

"There are subsets of people doctors can focus on when implementing cognitive screening, such as minorities, those with lower levels of education and those who come in by themselves," Amjad said.

The study was published in the July issue of the Journal of General Internal Medicine.

More information

The U.S. National Institute of Neurological Disorders and Stroke has more on dementia.