Brain laterality, depression and anxiety disorders: New findings for emotional and verbal dichotic listening in individuals at risk for depression

ABSTRACT

Studies using dichotic listening tests and electroencephalographic (EEG) measures of hemispheric asymmetry have reported evidence of abnormal brain laterality in patients having depressive disorders. We present new findings from a multigenerational study of risk for depression, in which perceptual asymmetry was measured in dichotic listening tests of emotional and verbal processing. Biological offspring and grandchildren of probands with a major depressive disorder (MDD) who were at high risk and those of nondepressed controls who were at low risk were tested on dichotic emotional recognition and consonant–vowel syllable tests. In the emotion test, individuals with a lifetime diagnosis of MDD had a smaller right hemisphere advantage than those without a MDD, but there was no difference between high- and low-risk groups or between those with or without an anxiety disorder. In the syllable test, a smaller left hemisphere advantage was found in individuals with an anxiety disorder compared to those without an anxiety disorder, but there was no difference between high- and low-risk groups or between those with or without a MDD. This double dissociation indicates that lifetime diagnosis of MDD and anxiety disorders have a differential impact on lateralized hemispheric processing of emotional and verbal information.

KEYWORDS:

• Depression
• anxiety disorders
• risk for depression
• laterality
• dichotic listening

Acknowledgements

The authors thank Kenneth Hugdahl of the University of Bergen, Norway, for providing a CD and instructions for administering the dichotic syllable test and for his comments on this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

¹After excluding those with a hearing loss greater than 30 dB or ear difference greater than 10 dB at 500–2,000 Hz, the hearing levels for participants were well within the normal range (i.e. generally ≤ 20 dB loss). We cannot rule out the possibility that hearing loss at frequencies higher than 2,000 Hz could have influenced our findings. It is, however, unlikely that the differences in PA on the emotional recognition test between participants with vs. without a lifetime MDD or differences in PA on the syllable test between participants with vs. without a lifetime anxiety disorder were due to differences in the hearing level. An ANOVA of hearing levels at 500, 1,000 and 2,000 Hz in each ear indicated that there was no significant difference in the hearing level between these groups and no group by ear interaction (all p-values ≥.28). Moreover, neither overall hearing levels or ear difference in hearing levels correlated with PA scores for the emotional recognition test (r ≤ .01, p ≥ .67) or the syllable test (r ≤ 0.12, p ≥ .19).

Additional information

Funding

This research was funded by NIMH Grant MH036197 (MMW).