HHTM Staff: For several years, we’ve been reporting on correlations linking hearing loss and Alzheimers, depression, cognitive decline, social isolation, general health, and Quality of Life (QoL) measures. Correlation does not imply causality, but the data keep coming, forging stronger links between healthy hearing and healthy living. November is also National Alzheimer’s Awareness month and we want to highlight this challenging disease and connections to hearing loss whether they are linked to cause or just connected in some way.
In 2012, Jane E. Brody published a thoughtful piece in the New York Times entitled Lifelines for Hearing Loss which draws many of those threads together. It’s worth clicking on the link to read the full article, but we’ll give you its first sentence to whet your interest:
Hearing loss, a disability currently untreated in about 85 percent of those affected, may be the nation’s most damaging and costly sensory handicap.
We hope you’ll read her excellent review, which is written for the general public.
Another report published in the September 6, 2011 issue of the Annals of Internal Medicine is written for an audience of scientists. You may not want to slosh through it, so we’ll hit some highlights here and try to make it clear how the study was done. You can also go to the “summary for patients” version prepared by the authors to get a more complete encapsulation.
The researchers collected reports of cognitive screening during routine medical exams performed from 1991 to 1993 on about 4000 older adults from diverse backgrounds. The study followed those 4000 for 13 years and found that:
mild and moderate to severe cognitive impairment at baseline was associated with an increased risk for death over roughly the next decade after controlling for other mortality risk factors.
The study was compelling because it characterized the effects of even mild cognitive impairment on life expectancy as on the same order as diabetes and other chronic diseases. If you’re wondering how commonly cognitive impairment showed up, it was present at baseline in about 20.2% of the adults, but that doesn’t tell us much because of the large range of subject’s ages: 60-102 years when they were first screened.
What does make the data interesting is the manner in which the researchers tracked those who were screened. They looked only at the 60.3% who died in the 13 year period and measured the number of months each subject lived. The median number of months for all of those subjects was 129 months (10.75 years). Then, they measured the number of months subjects lived according to their cognitive status. The results, shown in Table 1, make it clear that those with cognitive impairment had shorter life spans compared to those with normal cognitive function. The median length of life for subjects with moderate cognitive impairment was 6.25 year less than that of those with normal cognition.
The authors draw conclusions related to treatment options for older people, depending on their cognitive state. For our purposes, we look at this study and consider the implications of Jane Brody’s article (above):
Correlation is not causality, but the links between hearing loss-dementia-Alzheimer’s disease, together with the links between cognitive impairment and longevity, make us want to hedge our bets and those of our patients by encouraging them to optimize their hearing abilities, in hopes of allaying cognitive problems, in hopes of prolonging meaningful life. To the extent that these hopes are realized, the cost of hearing aids becomes small compared to the savings of good cognitive function and longer, fuller lives.
To clinicians: consider incorporating two short screening tools for cognitive assessment into your practice: the Short Portable Mental Status Questionnaire used in the study described above; also the Mini Mental State Exam (MMSE).
photo courtesy of Darroch Hearing