Recognizing Central Auditory Processing Disorder

Hearing Loss in the Elderly Often Coincides with CAPD, Making Diagnosis More of a Challenge

Shechar Dworski, MSc

Hearing is an important part of our sensory system; it enables us to interact with our environment and to communicate verbally with others. Twenty percent of those over the age of 65, and 40% of those over the age of 75, have significant hearing loss, and at least 80% of nursing home residents have some degree of hearing loss.1 There are two types of hearing impairment: peripheral and central. Peripheral damage to the ears can be caused by anything from the build up of cerumen to a perforated eardrum (for a description of peripheral hearing loss, see the articles on Hearing Loss and on Biology of the Aging Ear). Central processing impairment involves the dysfunction of certain areas of the brain's higher auditory centres that are responsible for hearing, language and comprehension. Causes of hearing loss include tumours, ototoxi-city from certain drugs, noise exposure and injury to the cochlear nerve and brain, as well as age-related degeneration of the ear and the associated neural pathways.

Impairments to the hearing process which occur in the brain are called central auditory processing disorders (CAPDs). With CAPDs, hearing impairment seems apparent even in the absence of any peripheral causes of hearing loss. CAPD can be defined as an impaired ability to recognize, discriminate, and/or comprehend auditory information.