SRF301 - A Simple Test to Screen for Hearing Difficulties and Cognitive Decline

Abstract:
A Digit in Noise Test (DINT) using 2-, 3-, 4- and 5-digit sequences was developed to screen for hearing difficulties and cognitive decline in Chinese older adults. While the 2-digit DINT primarily evaluates speech perception and can be administered quickly to screen hearing, 5-digit speech reception threshold (SRT) significantly related to cognitive function, and more so than other digit sequences. A preliminary study in 81 older hearing aid users showed that the difference in SRT obtained using 5- and 2-digits could potentially be used as an indicator for the need to refer for cognitive function screening.

Summary:
Rationale
Given the high prevalence of hearing loss and mild cognitive impairment (MCI) in older adults (WHO, 2021; Ward et al., 2012), audiologists should be mindful of the co-existence of cognitive decline and refer for evaluation when appropriate (Shen et al., 2016; 2020). Although both can affect speech understanding in challenging conditions in older adults (Moore et al., 2014; Wong et al., 2014), it is sometimes difficult to clinically distinguish them without conducting a cognitive function test. Although Shen et al (2016) recommended that audiologists should be trained to properly administer the cognitive test, not all audiologists would feel comfortable doing so and some may worry about the time burden in a busy clinical setting.

To tackle these issues, a Digit In Noise Test (DINT) was developed to incorporate test stimuli in four digit sequences (2-, 3-, 4- and 5-digits). 3-digit DINTs have been used successfully in hearing screening and have been found to have good test-retest reliability and criterion validity in different language versions (Akeroyd et al., 2015; Borre et al., 2021). As working memory is involved in remembering and repeating the digits heard, it is expected that as the number of digits increases, listeners will have more difficulties performing the DINT, resulting in poorer speech reception thresholds (SRT), regardless of hearing sensitivity and cognitive function. Therefore, the current study would examine the impact of the number of digits on the measurement of SRT and in particular, whether SRT measurement with 5 digits would significantly indicate the need for referral for cognitive testing.

Design
The study sample consisted of 32 normal hearing young adults and 81 older adult hearing aid (HA) users with moderate to severe hearing loss. 2-digit and 5-digit DINT were used to assess the SRTs. The Chinese version of the Montreal Cognitive Assessment Basic (MoCA-BC) was used to determine if older adults exhibited potential MCI. The Digit Span Test (DST) was used to measure working memory capacity. The relationship between SRTs obtained using 2- to 5-digit DINT, and the difference in SRT between 2- and 5-digits (5-2diff), and results from cognitive function tests was explored.

Results
While SRTs from all digit sequences related significantly to DST scores, higher correlations between these measures were noted with 5-digit sequence. 5-2diff also correlated significantly with DST scores (r = -.70). 5-2diff was statistically significantly lower in young adults (M = 0.98 ± 1.02) and older adults who passed the MoCA-BC (M = 1.38 ± 1.11) compared to older adults who failed the MoCA-BC (M = 4.59 ± 1.35), ps < .001. A receiver operating characteristic curve showed that with a cut-off point of 3.08, 5-2diff effectively distinguished whether the older adults passed MoCA-BC, with sensitivity of 1 and specificity of 0.95.

Conclusions
DINT using 2-digit, 5-digit and 5-2diff has the potential to indicate issues of cognitive function while achieving speech perception in noise assessment in older HA users. further research will be performed to evaluate the effects of more severe cognitive decline and hearing loss on SRTs and 5-2diff.