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.

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