Hearing Loss May Predict Cognitive Decline

In that it is projected that by the year 2050, an estimated 100 million people worldwide will be affected by dementia, interventions that could delay the onset of dementia by even one year could lead to a more than 10% decrease in disease prevalence. Frank R. Lin, from Johns Hopkins Medical Institutions (Maryland, USA), and colleagues studied 639 individuals, ages 36 to 90 years, without dementia. Participants initially underwent cognitive and hearing testing and were subsequently followed for the development of dementia and Alzheimer's disease. Of the participants, 125 had mild hearing loss (25 to 40 decibels), 53 had moderate hearing loss (41 to 70 decibels) and six had severe hearing loss (more than 70 decibels). During a median (midpoint) follow-up of 11.9 years, 58 individuals were diagnosed with dementia, including 37 who had Alzheimer's disease.   The team observed that the risk of dementia was increased among those with hearing loss of greater than 25 decibels, with further increases in risk observed among those with moderate or severe hearing loss as compared with mild hearing loss. For participants age 60 and older, more than one-third (36.4%) of the risk of dementia was associated with hearing loss. As well, the risk of developing Alzheimer's disease specifically increased with the extent of hearing loss, such that for every 10 decibels of hearing loss, the extra risk increased by 20%.  Writing that: “Hearing loss is independently associated with incident all-cause dementia,” the researchers submit that: “Whether hearing loss is a marker for early-stage dementia or is actually a modifiable risk factor for dementia deserves further study.”

Frank R. Lin; E. Jeffrey Metter; Richard J. O’Brien; Susan M. Resnick; Alan B. Zonderman; Luigi Ferrucci.  “Hearing Loss and Incident Dementia.”  Arch Neurol, Feb 2011; 68: 214 - 220.