| Message: Dichotic Dysaudia occurs when both ears are weak at transferring auditory information to the correct brain hemisphere. A child with either of these deficits will struggle to hear in a noisy classroom and will generally have poorer attention than their peers.
Auditory processing is a term used to describe what happens when your brain recognizes and interprets the sounds around you. Humans hear when energy that we recognize as sound travels through the ear and is changed into electrical information that can be interpreted by the brain.
Dichotic listening is the auditory process that involves listening with both ears. ... Binaural separation is the ability to perceive an acoustic message in one ear while ignoring a different acoustic message in the other ear.
Dichotic listening (DL) tests are among the most frequently included in batteries for the diagnosis of auditory processing disorders (APD) in children. A finding of atypical left ear advantage (LEA) for speech-related stimuli is often taken by clinical audiologists as an indicator for APD.
Dichotic listening is a psychological test commonly used to investigate selective attention and the lateralization of brain function within the auditory system. It is used within the fields of cognitive psychology and neuroscience.
Key Points
Question Is the association between poor hearing and dementia associated with signal sensitivity, central auditory processing, or both?
Findings In this prospective cohort study of 280 adults without dementia, measures of dichotic auditory processing were associated with increased dementia and Alzheimer dementia risk independently of signal sensitivity. Measures of signal audibility had a weak and insignificant association with dementia risk, and that association disappeared when controlling for dichotic auditory processing.
Meaning The associations between poor hearing and dementia risk may be more specific to dichotic processing than signal audibility or monaural speech tests.
Abstract
Importance Age-related hearing difficulties can include problems with signal audibility and central auditory processing. Studies have demonstrated associations between audibility and dementia risk. To our knowledge, limited data exist to determine whether audibility, central processing, or both drive these associations.
Objective To determine the associations between signal sensitivity, central auditory processing, and dementia and Alzheimer dementia (AD) risk.
Design, Setting, and Participants This follow-up observational study of a sample from the prospective Adult Changes in Thought study of dementia risk was conducted at Kaiser Permanente Washington, a western Washington health care delivery system, and included 280 volunteer participants without dementia who were evaluated from October 2003 to February 2006 with follow-up through September 2018. Analyses began in 2019 and continued through 2021.
Exposures Hearing tests included pure tone signal audibility, a monaural word recognition test, and 2 dichotic tests: the Dichotic Sentence Identification (DSI) test and the Dichotic Digits test (DDT).
Main Outcomes and Measures Cognition was assessed biennially with the Cognitive Abilities Screening Instrument (range, 1-100; higher scores are better), and scores of less than 86 prompted clinical and neuropsychological evaluations. All data were reviewed at multidisciplinary consensus conferences, and standardized criteria were used to define incident cases of dementia and probable or possible AD. Cox proportional hazard models were used to determine associations with hearing test performance.
Results A total of 280 participants (177 women [63%]; mean [SD] age, 79.5 [5.2] years). As of September 2018, there were 2196 person-years of follow-up (mean, 7.8 years) and 89 incident cases of dementia (66 not previously analyzed), of which 84 (94.4%) were AD (63 not previously analyzed). Compared with people with DSI scores of more than 80, the dementia adjusted hazard ratio (aHR) for DSI scores of less than 50 was 4.18 (95% CI, 2.37-7.38; P < .001); for a DSI score of 50 to 80, it was 1.82 (95% CI, 1.10-3.04; P = .02). Compared with people with DDT scores of more than 80, the dementia aHR for DDT scores of less than 50 was 2.66 (95% CI, 1.31-5.42; P = .01); for a DDT score of 50 to 80, it was 2.40 (95% CI, 1.45-3.98; P = .001). The AD results were similar. Pure tone averages were weakly and insignificantly associated with dementia and AD, and associations were null when controlling for DSI scores.
Conclusions and Relevance In this cohort study, abnormal central auditory processing as measured by dichotic tests was independently associated with dementia and AD risk. |
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