Aging and hearing loss: results of the PAQUID longitudinal study

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Published on 08 December 2015

Aging is associated with gradual decline in neurosensory performance, particularly hearing abilities. 30% of people over 65 years of age have some degree of hearing loss, and up to 70% to 90% of those 85 years and older (Chien & Lin, 2012).

“Use of hearing aids attenuates cognitive decline in elderly people with hearing loss”. This is the conclusion reached by a team of researchers at Unit 897 Epidemiology and Biostatistics of the French National Institute for Health and Medical Research (Inserm) in Bordeaux. The findings were published in late October in the Journal of the American Geriatrics Society, as you read a preview here. Exclusively for Audio Infos/Audiology Worldnews, Hélène Amieva from the INSERM team tells us about the important findings from the study.

High prevalence of hearing loss in elderly population often makes hearing loss seem normal since only one in three people in this population with a hearing impairment is thought to use hearing aids (Fisher et al., 2011). However, precisely because of this high prevalence and the probable repercussions on mood and functioning, rehabilitation of hearing impairment in elderly people is a major public health challenge. Several studies have pointed to the role of hearing loss in levels of cognitive performance (Lin et al., 2011; Valentijn et al., 2005), depression, social activities, day-to-day tasks, or even dementia (Kiely et al., 2013; Li et al., 2014; Thomas et al., 1983; Strawbridge et al., 2000; Weinstein et al., 1982). In a recent US epidemiological study, a relationship was found between the severity of hearing loss and cognitive decline in 1,984 patients aged 70 to 79 years, with follow-up over six years (Lin et al., 2013).

Nonetheless, there is little data on long-term decline in elderly people with hearing loss or on the possible effect of rehabilitation of these impairments through use of hearing aids. Thanks to the very long-term data now available from the PAQUID epidemiological study, and since data on hearing disorders were collected at the enrollment visit, we were able to analyze the effect of hearing impairment, with or without hearing assistance, on changes in cognitive functions in a study cohort with follow-up over 25 years. This article sums up the results of this recently published study (Amieva et al., 2015).

PAQUID study carried out in Bordeaux

PAQUID (in French, "personnes âgées QUID" or "elderly people as subject matter" is a longitudinal population cohort study (Dartigues et al., 1992). It is well known in the area of geriatrics and has given rise to many publications, specifically on the epidemiology of Alzheimer’s disease and dependence. Initiated in the early 1990s, the PAQUID cohort included 3,777 participants aged 65 years and over, living at home, in the Gironde and Dordogne departments of Southwest France, on the basis of random selection from lists of voters. Each of the study visits, including the inclusion visit, was carried out at the participant’s home. About every two years, study participants had an appointment with a psychologist who assessed their state of health on the basis of various questionnaires, scales, and tests concerning their physical, functional, psychological and cognitive health. A neurologist or geriatric physician also visited the subjects if dementia was suspected. Participants were thus followed-up for 25 years, making the PAQUID cohort one of the epidemiological studies in geriatrics with the longest follow-up periods worldwide.

Analytical method

For this study, the sample included 3,772 subjects, after exclusion of people with existing dementia, i.e. detected at the inclusion visit. At this initial visit, two questions specifically concerned hearing impairment and use of hearing aids. Of the 3,772 participants answering this question, 2,443 reported no problematic hearing loss, 1,178 reported moderate impairment, particularly when following a conversation with several speakers or in a noisy environment, and 151 reported major impairment. Among those reporting moderate to major impairment (1,329 subjects in all), 150 used a hearing aid and 1,179 did not.

In addition, at each follow-up visit, participants were asked to carry out a MMSE -Mini-Mental State Examination- test (Folstein et al., 1975), a test commonly used in the area of geriatrics to assess overall cognitive function in elderly people. The test has 30 points that evaluate memory, attention, calculation abilities, language, and visuoconstruction abilities.

Changes in this test score over the 25 years of cohort follow-up were modelled using mixed linear regression. Three regression models were used in succession:

• The first model involved comparing changes in the MMSE test score in subjects with and without hearing impairment, independently of gender, age, and level of education.
• The second model looked at the use of hearing aids. Its aim was to compare changes in MMSE test scores in three groups of subjects: the group without hearing impairment, considered the control group, the group with hearing loss and no hearing aids, and the group with hearing loss and use of hearing aids. Adjustment variables were restricted to the three main confounding variables for cognitive performance: gender, age, and level of education.
• In the third model, the same three groups were compared. However, in addition to gender, age, and education level, other psychosocial variables were also considered, for instance intake of psychotropics, depressive symptoms, or measures indicating social networks (number of visits received, satisfaction with social network, etc.).

Main results

In the first statistical model, results showed that over the 25 years of follow-up, people with hearing loss had a statistically significant greater decline in MMSE test scores than people with no hearing impairment.

However, the second model showed that only the group of subjects without hearing aids had this statistical greater decline than the control group, in other words people with no hearing impairment. Changes in MMSE scores for people with hearing impairment and who used hearing aids were not different from those of the control group.

In the third statistical model, in which psychosocial variables were considered, the increased decline related to hearing loss was no longer statistically significant, including in people who did not wear hearing aids.

Discussion

This study supports the findings reported by Lin et al. (2013) but in a sample twice the size and with far longer follow-up. In this way, it confirms that there is accelerated cognitive decline in elderly people with hearing impairment.

There does however not appear to be a direct relationship between hearing loss and cognitive decline. Many studies have demonstrated the relationship between hearing loss and depressive symptoms, and decreased leisure activities and social interactions. These results are in line with the results of our study because when psychosocial variables are considered, the greater decline related to hearing loss was no longer statistically significant, including in people who do not use hearing aids. This result clearly shows that the relationship between hearing loss and cognitive decline can be explained by social isolation and depressed mood, which develop gradually in elderly people with hearing loss. Accelerated cognitive decline in the elderly with hearing impairment therefore appears to be preventable.

Our study has shown that cognitive decline in people with hearing loss using hearing aids is not different from that of subjects with no hearing loss. This result has not been found until now. We can therefore hypothesize that use of hearing aids positively affects cognition by restoring communication abilities, at least partially, which in turn promotes continued social and leisure activities, and a certain degree of quality of life.

Conclusion

Although hearing loss is common in the elderly, it should not be considered a normal part of aging since there is now a large body of evidence indicating that it contributes to accelerated cognitive decline associated with age. For the first time, our study shows that people with hearing aids do not have this accelerated decline. Our findings therefore support the need for screening and rehabilitation of hearing loss in elderly people. Along with other prevention strategies such as physical exercise and a Mediterranean-type diet, maintaining good hearing should be one of the strategies used to promote “successful aging” in elderly people.

Watch the interview to Prof Hélène Amieva in English here!