"The increased mortality of older patients with dementia hospitalized for flu may be indicative of inadequacies in health-care quality and accessibility," the study's senior author, Elena Naumova, a professor of public health and community medicine at Tufts University School of Medicine, said in a university news release. "It could be beneficial to refine guidelines for the immunization, testing and treatment of flu in older patients with dementia when planning for the possibility of a flu pandemic."

She and her colleagues analyzed five years of data, from 1998 to 2002, from the U.S. Centers for Medicaid & Medicare Services, including 36 million hospitalization records for people 65 and older. More than 6 million people had a pneumonia and influenza diagnosis, including more than 800,000 (13 percent) with dementia.

Early diagnosis and treatment of flu in people with dementia can be difficult because they often have trouble communicating as a result of poor oral hygiene or impaired swallowing, the researchers said. This can make it difficult to talk to doctors about symptoms or complications.

The researchers also believe that limited access to health-care services and inadequate testing practices could contribute to lower rates of flu diagnosis and higher rates of death among older people with dementia. Their analysis of the data showed that pneumonia and flu rates were highest among older adults in poor and rural areas, where there are fewer health-care centers.

"Limited access to specialized health-care services can delay diagnosis and treatment of the flu, causing it to progress to pneumonia, the fifth leading cause of death among the elderly," Naumova said. "This study has helped us identify this vulnerable population, and now further study is needed to confirm the findings and assess the testing and vaccination policies for older patients with dementia.

The study was published online Oct. 26 in the Journal of the American Geriatric Society.

More information

The U.S. Centers for Disease Control and Prevention has more about seasonal flu.