Response to Wallhagen and Strawbridge.

Abstract

We agree with Drs. Wallhagena and Strawbridge1 that our study2 has several limitations, in particular that the question on whether the individuals had hearing aids was asked only at baseline and that the study relied on information regarding possession of hearing aids, whereas reporting having a hearing aid does not necessarily mean that one uses it regularly. Such limitations were not undervalued; to the contrary, they were clearly stated in the Discussion section. It is not clear why using the Mini-Mental State Examination (MMSE) in a study on cognitive decline in elderly adults is a concern. Even though the MMSE has limits—as do all cognitive measures—it is the most widely used measure of cognition in elderly adults. There is a vast literature that would be difficult to synthetize showing that decline in MMSE score is a relevant marker of cognitive decline in aging. Yes, it is related to education, and yes, it is related to age. Nearly all the authors of the study are neurologists or neuropsychologists and do not ignore the effect of education on cognitive performances. As mentioned in the tables and the Methods section, all statistical analyses were corrected for age and education, which means that changes in MMSE score in the groups were compared independent of age and education (and sex). Finally, the third statistical model of the study was conducted to help understand the association between hearing aids and cognitive decline and to avoid overinterpretation regarding the effect of hearing aids because it is highly unlikely that hearing aids have a direct effect on cognition. After statistically controlling for psychosocial variables, showing that cognitive decline in older adults with hearing impairment was no longer different from that of controls, it was hypothesized that depression and social isolation could mediate the association. This rationale is presented as a hypothesis, not as a conclusion. We fully agree it should be tested by other research. Far from considering that our study provides definitive and unquestionable evidence of the effect of hearing aid use on cognition, we clearly state in the article—in the Discussion and Conclusion sections—that the question of whether hearing aids affect cognitive decline could be addressed only in a randomized controlled trial. We hope that our study will lead to further research assessing the real effect of the treatment of hearing impairment in elderly adults. With some two-thirds of elderly adults experiencing hearing impairment, this question deserves to be studied. Conflict of Interest: The author has no financial or other personal conflict with this letter. Author Contributions: The author was the sole author of this letter. Sponsor's Role: None.