( Health.com ) -- Gradual hearing loss is a common symptom of aging , but in some people it may also be an early sign of Alzheimer 's disease or other types of dementia , a new study suggests . The risk of dementia appears to rise as hearing declines . Older people with mild hearing impairment -- those who have difficulty following a conversation in a crowded restaurant , say -- were nearly twice as likely as those with normal hearing to develop dementia , the study found . Severe hearing loss nearly quintupled the risk of dementia . Health.com : 25 signs and symptoms of Alzheimer 's Disease . It 's unclear why the loss of hearing and mental function might go hand in hand . Brain abnormalities may contribute independently to both conditions , but it 's also possible that hearing problems can help bring on dementia , the researchers say . Hearing loss may lead to social isolation ( which itself has been linked to dementia ) , for instance , or it may interfere with the brain 's division of labor . `` The brain might have to reallocate resources to help with hearing at the expense of cognition , '' says the lead researcher , Frank R. Lin , M.D. , an ear surgeon at Johns Hopkins Hospital in Baltimore . That may explain in part why straining to hear conversations over background noise in a loud restaurant can be mentally exhausting for anyone , hard of hearing or not , he adds . The findings suggest that poor hearing is a `` harbinger of impending dementia , '' says George Gates , M.D. , a hearing expert at the University of Washington in Seattle , who was not involved in the new study but whose own research has demonstrated a link between the two conditions . `` We listen with our ears but hear with our brains , '' Gates says . `` It is simply not possible to separate audition and cognition . '' Health.com : 9 foods that may help save your memory . In the study , which appears in the Archives of Neurology , Lin and his colleagues followed more than 600 dementia-free adults between the ages of 36 and 90 for an average of 12 years . A little less than 30 percent of the study participants had some hearing loss at the start of the study . Overall , 9 percent of the participants went on to develop Alzheimer 's disease or another form of dementia . Mild , moderate , and severe hearing loss were associated with a two-fold , three-fold , and five-fold higher risk of later dementia , respectively , in comparison to normal hearing . People with moderate hearing loss generally struggle to communicate even in quiet settings , and those with severe hearing loss are near deaf . Lin says that hearing loss has an enormous impact on the lives of his patients and their family members . `` Yet because it is such a slow and insidious process , it is often left ignored and untreated . '' Whether hearing aids or other treatments ( such as cochlear implants ) can help stave off dementia is the `` 50 billion dollar question , '' Lin adds . Thirty million Americans currently have impaired hearing and 1 in 30 are predicted to suffer from dementia by 2050 , so if those treatments prove to be helpful , their impact would be felt widely . Health.com : Aging workforce means dementia on the job could rise . There is no cure for dementia , and there are no surefire ways of preventing it . Gates is n't optimistic that restoring hearing can affect the course of dementia . However , if treatments and prevention strategies for dementia do become available in the future , he says , hearing loss could play an important role in early detection . Lin and his colleagues have begun researching the effect of hearing aids on the risk of dementia . `` Whether or not it can help dementia , we do n't know yet , '' he says . `` But in the meantime , there 's no reason not to take your hearing loss seriously and pursue some type of treatment . '' Copyright Health Magazine 2011 .
In some people , gradual hearing loss may also be an early sign of types of dementia . Comment: 30 million Americans have impaired hearing ; dementia predicted for 1 in 30 by 2050 .