Decrease in cerebral volume accelerated in hearing impaired


A team of researchers from Johns Hopkins University and the National Institute on Aging, Baltimore, Maryland (USA), have used magnetic resonance neuroimaging studies to evaluate the effects of hearing deficits on cerebral atrophy.

Previous studies have shown that hearing impairment in older adults is associated with accelerated cognitive decline and incident dementia, and with reduced volumes in the auditory cortex. But it is not known whether it is related to accelerated rates of brain atrophy.

The researchers analyzed brain volume measurements on the basis of brain scans for 51 individuals with hearing impairment (speech-frequency pure tone average > 25 dB) and compared results with scans for people with normal hearing included in the Baltimore Longitudinal Study of Aging. The study patients were followed-up for a mean of 6.4 years after a baseline scan and were between 56 and 86 years of age.

Results showed that the hearing impairment group had accelerated volume decreases in whole brain and regional volumes in the right temporal lobe. Interestingly, the atrophy over time was mainly found in temporal lobe structures that are important for spoken language processing. After adjustment for confounding factors, the results appear to be robust, according to the team. One explanation could be a common cellular aging process leading to both cochlear and brain aging. Reduced neural stimulation of the auditory cortex may however also be involved as a result of altered auditory signal processing.

The findings provide more data on the discussion of whether peripheral hearing impairment has broader implications for brain structure and function.

Source: Lin FR, et al. Association of hearing impairment with brain volume changes in older adults. Neuroimage. 2014 Jan 9; 90C:84-92