Hearing Loss, Memory And Dementia.

Nov. 4, 2011 - PRLog -- Hearing loss is considered the planet’s  most prevalent personal injury with an estimated 10 per cent, or almost 600 million people worldwide, possessing some form of hearing impairment. It is also estimated that 35 million people worldwide have Alzheimer's disease, the most common form of dementia.

New research being conducted into the relationship between undiagnosed hearing loss, memory and dementia suggests the true extent of the effects of sustaining hearing damage, most often the result of years of exposure to excessive noise levels in the workplace.

According to results from recent studies, many men and women may be presented with false “positive” results from cognitive tests, which identify signs of dementia but are misdiagnosed because of undetected noise induced hearing loss. With around 12 per cent or one in eight people aged over 65 suffering from dementia, and more than 50 per cent aged over 70 possessing hearing loss, it's not uncommon for the two conditions to coexist.

A brief test of cognitive skills, including attention span and memory, in a recent study of 1,600 elderly patients, suggested 900 showed signs of dementia. However, following a hearing test and subsequent treatment, one third of those who originally were indicated as having possible dementia, were found instead to actually have a relevant hearing loss. Consequently, a significant improvement was shown in further cognitive testing results, after hearing treatment.

The problems of even a mild hearing loss, which means simply missing out words, can be overlooked and affect cognitive test performance, if not conducted by an experienced doctor.

Research has also found that sounds create after-vibrations in the inner ear, which are likely to function like a form of short-term memory. According to recent animal studies, ears can still hear sounds after the sound has ceased. This is because the hair cells in the inner ear not only move when they are directly affected by sounds but seem to continue to respond after the sound stops, depending on the strength of the sound and its’ frequency.

It is believed that the after-vibrations can have an effect on the ability to perceive sounds and language by detecting brief gaps in an ongoing stimulus critical for speech recognition. As the gaps need to be longer than a minimal interval to be perceived, the after-vibrations stimulate the auditory nerve fibres, and may be a partial explanation for the difficulty in detecting the gaps.

Consequently, even a minor hearing loss could lead to a substantial reduction in after-vibrations, making it difficult to detect the small gaps in an ongoing stimulus, which in turn affect speech recognition. Some hair cells respond to vibrations by producing forces that increase hearing sensitivity and frequency selectivity through mechanisms, which are at present, not completely understood by medical research.

Visit http://www.hearinglossadvice.co.uk   for more information and advice.

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