Hearing Loss and Accelerated Brain Tissue Loss

Hearing Loss and Accelerated Brain Tissue Loss

by Nobuko Ito, Au.D.

Study at Johns Hopkins University School of Medicine

A recent study by Frank Lin, M.D., Ph.D., Otolaryngologist and Assistant Professor in the schools of medicine and public health at John Hopkins University suggests that hearing impairment is associated with accelerated rates of brain atrophy. In his study published in NeuroImage on April 15, 2014 and supported by the National Institutes on Aging and Johns Hopkins University, Dr. Lin used magnetic resonance imaging (MRI) to document brain changes over a period of up to ten years in 126 individuals. Each individual also underwent annual hearing tests and physical exams. Of the 126 subjects, 75 had normal hearing at the beginning of the study, while 51 had hearing loss defined by at least 25dB or worse thresholds.

Shrinkage of Gray Matter

Accelerated brain atrophy was found in the individuals with hearing loss compared to individuals with normal hearing during the course of the study. Those with hearing loss of 25dB or more lost more than an additional cubic centimeter of brain tissue each year compared  with normal hearing subjects. Notably, the shrinkage occurred in the superior, middle, and inferior temporal gyri, which are areas of the brain responsible for processing speech and sound, in addition to playing a role in memory and sensory integration. Shrinkage of these areas have also been found in early stages of mild cognitive impairment and Alzheimer’s disease. Dr. Lin noted that the effect on the brain tissue might be related to a lack of stimulation to the auditory cortex.

Treatment of Hearing Loss is Important

The study also gives some urgency to treating hearing loss rather than ignoring it. “If you want to address hearing loss well,” Lin says, “you want to do it sooner rather than later. If hearing loss is potentially contributing to these differences we’re seeing on MRI, you want to treat it before these brain structural changes take place.”

It is important to note that the study does not show a causative effect, but rather a correlation of hearing loss and atrophy of gray matter. In addition to brain tissue shrinkage, it is well known that hearing loss has been associated with increased falling, depression, and poorer health. 

It is recommended that adults see an Audiologist for a hearing test regularly as part of their health check up.

Dr. Lin’s study was part of the Baltimore Longitudinal Study of Aging, which was started in 1958 by the National Institute on Aging. The gathering of information of various health issues of more than 1,300 men and women continues today as a valuable resource for study.