Speech in Noise Perception as a Marker of Cognitive Impairment in HIV Infection.

OBJECTIVES: Human immunodeficiency virus positive (HIV+) individuals report hearing difficulties, but standard audiological tests show no, or small, changes in peripheral hearing ability. The hearing complaints may reflect central nervous system (CNS) auditory processing deficits, rather than middle or inner ear problems, and may result from CNS damage due to HIV infection or treatment. If central auditory task performance and cognitive deficits in HIV+ individuals are shown to be related, then central auditory tests might serve as a "window" into CNS function in these patients.
DESIGN: We measured cognitive performance (Mandarin Montreal Cognitive Assessment [MoCA]) and speech in noise perception (Mandarin hearing-in-noise test [HINT]) in 166 normal-hearing HIV+ individuals (158 men, 8 women, average age 36 years) at the Shanghai Public Health Clinical Center in Shanghai, China. Data collection included audiometry, tympanometry, and the Amsterdam Inventory of Auditory Handicap (AIAH), which assesses the subjective ability to understand speech and localize sound.
RESULTS: Subjects had no middle ear disease and met criteria for normal-hearing sensitivity (all thresholds 20 dB HL or less). A significant negative relationship between speech reception thresholds (SRT) and MoCA scores (r = 0.15, F = 28.2, p < 0.001) existed. Stepwise linear regression showed that when the factors of age, MoCA scores, hearing thresholds, and education level were considered, only age and MoCA scores contributed independently to the SRT results (overall model r = 0.30, F = 38.8, p < 0.001). Subjective hearing complaints from the AIAH supported the HINT results. AIAH and MoCA scores were also related (r = 0.05, F = 8.5, p = 0.004), with those with worse MoCA scores having more problems on the AIAH. When the cohort was divided into those with normal and abnormal performance on the MoCA, those with abnormal performance on the MoCA had significantly higher average SRTs (p < 0.001).
CONCLUSIONS: Understanding speech in noise measured both objectively with the HINT and subjectively with the AIAH was inversely related to cognitive abilities despite a normal ability to hear soft sounds determined by audiometry. Although age was also an important independent factor affecting speech perception, the age relationship within the speech findings in this study may represent more than just age-related declines in speech in noise understanding. Although reliable data on disease duration are not available, the older members of this cohort likely had HIV longer and probably had more severe symptoms at presentation than the younger members because early detection and treatment of HIV in Shanghai has improved over time. Therefore, the age relationship may also include elements of disease duration and severity. Speech perception, especially in challenging listening conditions, involves cortical and subcortical centers and is a demanding neurological task. The problems interpreting speech in noise HIV+ individuals have may reflect HIV-related or HIV treatment-related, central nervous damage, suggesting that CNS complications in HIV+ individuals could potentially be diagnosed and monitored using central auditory tests.