A twin study of auditory processing indicates that dichotic listening ability is a strongly heritable trait

Abstract

We administered tests commonly used in the diagnosis of auditory processing disorders (APDs) to twins recruited from the general population. We observed significant correlations in test scores between co-twins. Our analyses of test score correlations among 106 MZ and 33 DZ twin pairs indicate that dichotic listening ability is a highly heritable trait. Dichotic listening is the ability to identify and distinguish different stimuli presented simultaneously to each ear. Deficits in dichotic listening skills indicate a lesion or defect in interhemispheric information processing. Such defects or lesions can be prominent in elderly listeners, language-impaired children, stroke victims, and individuals with PAX6 mutations. Our data indicates that other auditory processing abilities are influenced by shared environment. These findings should help illuminate the etiology of APDs, and help to clarify the relationships between auditory processing abilities and learning/language disorders associated with APDs.

The Derived Allele of ASPM Is Associated with Lexical Tone Perception

“…An obvious limitation to the current study is the small sample size (n  =  32 for the main behavioral finding), although it is consistent with a number of previous studies connecting higher-order functions and genetics [46]–[47] Nevertheless, our current findings provide a starting point for examining a number of questions related to ASPM. For example, future research can examine whether ASPM and spoken language processing is restricted to lexical tones, to all speech sounds, to all speech sounds requiring simultaneous processing within a short temporal window, or whether they are also linked to other specific linguistic functions such as syntactic processing in a larger population of participants.…”

“…All of our subjects scored within normal limits on all cognitive measures we assessed and had no reports of communication deficits. Furthermore, our study contributes to the understanding of the molecular genetics of pitch-related behaviors (e.g., music) and deficits (congenital amusia), which thus far have been found to have a genetic origin in twins [46], [47] and family-aggregation [48] studies.…”

Heritability of non-speech auditory processing skills

“…Our estimates of heritability for AP skills are comparable in magnitude to those of other hearing-related phenotypes including dichotic listening (~0.73) (23) and tune deafness (~0.71-0.80) (35), as well as related cognitive disabilities such as dyslexia (0.44-0.75) (36), phonological processing (~0.72)(37) and late language emergence (0.42-0.44) (38). These AP measures (BM, BM50, SMN and FD) also appear to be reliable and reproducible as evidenced by the similarity between our current data and those obtained through a different subject recruitment paradigm in the United Kingdom (20)(Supplemental Fig.…”

“…The DNA was PCR-amplified for STR markers and analyzed until genotypes at a minimum of 14 genetically unlinked marker loci could be scored for each twin pair. Twins were considered monozygous if they had concordant genotypes for all marker loci or dizygous if they had discordant genotypes for at least five STR markers (23). …”

“…We previously examined heritability of speech-based AP skills and estimated that approximately 73% of the variance in dichotic listening and 46% of the variance in time-compressed speech understanding were attributable to genetic variation in adults (23). Given the considerable cognitive and linguistic demands of these tests, concern arises as to whether the heritability estimates for dichotic and time-compressed speech reflect those demands rather than the auditory aspects of the tests.…”