MedicalResearch.com: What are the main findings of the study?
Dr. Chuan-Ming Li: We used data on adults 18 years or older from the National Health and Nutrition Examination Survey for the study and found that prevalence of moderate to severe depression was 4.9 percent for individuals who reported excellent hearing, 7.1 percent for those with good hearing and 11.4 percent for participants who reported having a little hearing trouble or greater hearing impairment (HI). Depression rates were higher in women than in men. The prevalence of depression increased as hearing impairment became worse, except among participants who were deaf. There was no association between self-reported HI and depression among people ages 70 years and older; however, an association between moderate HI measured by pure-tone threshold hearing exams and depression was found in women aged 70 years and older but not in men.
MedicalResearch.com: Were any of the findings unexpected?
Dr. Chuan-Ming Li: We did not find a significant relationship between depression and self-reported hearing impairment among male or female adults aged 70 years and older. Rather, we found a significant association between depression and a threshold-based measure of “moderate” HI, defined as better ear pure tone average between 35 and 50 dB hearing level, among females. These apparently inconsistent results may reflect the tendency of people in different age groups to assess their HI differently. For example, older people may be less likely to self-report HI activity limitations compared with younger people.
In the present study, the prevalence of depression increased as hearing difficulty became greater, i.e., from “excellent” hearing to “a lot of trouble” but decreased among those who self-reported as “deaf”. The strongest association was for those with moderate trouble hearing. One reason for this result may be that people with severe to profound hearing impairment have had a different experience in their exposure and access to hearing health care. They are much more likely to have been ‘discovered’ and encouraged to try rehabilitation (hearing aids, alternative listening devices, cochlear implants, etc.). Thus, their lower prevalence of depression may be because a higher proportion of them have had access to hearing health care services and thereby have obtained more help and earlier interventions than those with mild to moderate hearing impairment.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Chuan-Ming Li: People with any hearing impairment should access health care professional services and be willing to try rehabilitation (e.g. hearing aids, alternative listening devices, etc) if recommended. Health care professionals should be aware of increased risk of depression among adults with hearing loss and may be better able to improve the quality of life among people with hearing impairment by recognizing signs and symptoms of depression and referring patients for mental health services.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Chuan-Ming Li: Because of the cross-sectional nature of the survey, we cannot determine whether hearing impairment predates depression or to what extent self-reported depression may impact self-perceived hearing impairment.
According to WHO reports, depression ranks as the number 1 highest burden among chronic diseases and adult-onset hearing loss is likely number 2 (next highest burden) in ‘developed’ countries such as the US, Canada, Australia, Western Europe, etc. The “cause and effect” relationship between HI and depression is unknown. A longitudinal/prospective study may be needed. Further study is needed to find reasons why women suffer more depression than men.