DOMINO DISEASES

Health conditions that are linked

This week: hearing loss and dementia STUDIES have consistently suggested that hearing loss is one of the major risk factors for dementia.

One study quantified this, finding that severe hearing problems led to a five times greater risk of developing dementia; moderate hearing loss tripled it, and mild hearing loss doubled it, reported the journal JAMA Neurology in 2011.

One theory is that coping with hearing loss requires greater mental effort, using up reserves that would otherwise be used for other functions, such as memory or attention. The lack of reserves for these other functions leads to symptoms of cognitive decline and dementia — this is known as ‘cognitive reserve theory’. Hearing loss may also alter brain structure, with some research suggesting it reduces brain volume, while others suggest hearing loss increases social isolation, a known risk factor for dementia.