19 Auditory and Cognitive Function in Adults Living With and Without HIV

Abstract

Objective:

Hearing consists of peripheral components (outer and middle ear, cochlea) and the central auditory system (cochlear nuclei to the auditory cortex). Speech perception relies on peripheral hearing abilities (i.e., pure-tone thresholds) and central auditory processing (CAP) and cognitive functioning. Specifically, working memory, executive function, attention, and verbal functioning allow for speech understanding. As a result, CAP deficits are also influenced by peripheral hearing sensitivity and cognitive functioning. Assessing CAP deficits can be difficult because of these complex interactions. Prior work has shown persons living with HIV (PWH) are at higher risk for sensorineural hearing loss compared to persons living without HIV (PWOH) after adjusting for age, sex, and noise exposure. Further, HIV is a risk factor for cognitive impairment, one example being Alzheimer's disease (AD) and its precursor, Mild Cognitive Impairment (MCI), with auditory dysfunction occurring in earlier stages of AD. Therefore, the purpose of this study was to evaluate: 1) the peripheral hearing sensitivity and CAP in PWH and PWOH; and 2) the association between cognitive function measures and CAP in PWH and PWOH.

Participants and Methods:

Participants included 59 PWH (39 men and 20 women, mean age=66.7 years [SD=4.4 years]) and 27 PWOH (13 men and 14 women, mean age=71.9 years [SD=7.1 years]). Participants completed a standard neuropsychological battery assessing the domains of learning, recall, executive function, working memory, verbal fluency, processing speed and motor. Raw scores were transformed to demographically corrected, domain T-scores. Cognitive function was normal for 39 (66.1%) PWH and 16 (59.3%) PWOH while 43 (72.9%) PWH and 17 (63.0%) PWOH were determined to have MCI. Participants with dementia were excluded. Participants also completed a hearing assessment, a portion of which consisted of pure-tone thresholds, peripheral hearing measure, and dichotic digits testing (DDT), a CAP measure. Pure-tone air-conduction thresholds were obtained at octave frequencies from 0.25 through 8 kHz, including 3 and 6 kHz. A pure-tone average (PTA) was calculated from 0.5, 1, 2, and 4 kHz thresholds for each ear. The DDT involves the presentation of numbers from 1 to 10, excluding 7, in which two different digits are presented to one ear while two other digits are simultaneously presented to the opposite ear. The outcome of DDT is percent correct.

Results:

PWH had slightly lower (i.e., better) mean PTAs in both ears compared to PWOH, but this was not statistically significant. Conversely, PWH had lower percent correct DDT results compared to PWOH, but this difference was also not statistically significant. Participants with impairment in verbal fluency, executive functioning, and working memory had significantly worse DDT results by approximately 10%, but only for right ear data.

Conclusions:

PWH in our sample had better hearing than PWOH, which can be explained by PWH having a lower mean age. PWH had poorer DDT results, however, indicative of CAP deficits rather than peripheral hearing problems. Poor right ear DDT was associated with impairments specifically in frontal-based cognitive processes with an executive component.