Distinguishing difficulties in speech understanding due to hearing loss and cognitive decline

Authors: Shangqiguo Wang *1; Lena Wong 1

1 University of Hong Kong

Background: Early screening for both hearing loss (HL) and cognitive decline are crucial in order to facilitate prompt intervention and treatment. However, there is currently a dearth of screening tools that are rapid, simple, and effective, and which can be applied on a global scale in clinical practice. In addition, HL could affect the accuracy of cognitive test results and make cognitive screening especially challenging. To tackle these issues, the first integrated test that can be used to simultaneously screen both hearing and cognitive function will be evaluated in the current study. The integrated Digit-in-Noise (iDIN) Test evaluates the reception of test stimuli that consist of 2, 3, 4 or 5 digit sequences.

Method: The study sample consisted of 32 normal hearing young adults and 81 older adult hearing aid users with moderate to severe HL. 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 relationships between SRTs obtained using 2- to 5-digit SRT, and the difference in SRT between 2- and 5-digits (SRT 5-2), and results from cognitive function tests were explored.

Results: While SRTs from all digit sequences related significantly to DST scores, higher correlations between these measures were noted with 5-digit SRT. SRT 5-2 also correlated significantly with DST scores (r = -.70). A receiver operating characteristic curve showed that with a cut-off point of 3.15, SRT 5-2 effectively distinguished whether the older adults passed MoCA-BC, with sensitivity of 0.905 and specificity of 0.933.

Conclusions: The iDIN test using 2-digit, 5-digit and SRT 5-2 has the potential to indicate issues of cognitive function in listeners who have hearing loss. Further research will be conducted to evaluate the effects of more severe cognitive decline and hearing loss on SRTs and SRT 5-2.

Fig 1. SRTs among older adults with HL are significantly worse than young adults with normal hearing. 5-digit SRT is significantly worse among older adults, in the presence of a cognitive decline.

Fig 2.  SRT5-2 is significantly worse among older adults with cognitive decline than those with normal cognitive function (young normal hearing listeners and older adults with HL).