Neuro

We are living longer!

(United Nations Population Fund, 2012)

Otogerontology

The study of anatomical, physiological, audiological, and other changes in aging auditory system

Age-Related Hearing Loss (ARHL)

Presbycusis

From Greek

Presbys = elder

Akousis = hearing

First coined by Zwaardemaker in 1899.

Presbycusis is more common in men than women.

One of the most common conditions affecting older adults. (NIDCD, 2018)

• Gradual
• Progressive
• Bilateral
• Symmetrical
• High frequency sensorineural hearing loss
• Can be associated with tinnitus

• Difficulty understanding speech in noisy and reverberant environments—the key symptom of central presbycusis.

• Interference with the perception of rapid changes in speech (temporal processing).

• Impairment sound source localization.

Aging affects both the peripheral and central auditory systems

Physiological Changes in Aging Auditory System

• Schuknecht estimated that 2100/35000 neurons are lost every decade.

• The loss of 50% of afferent nerve results in decreased speech discrimination.

• 90% of loss elicits a change in hearing threshold.

• Decrease brain volume and thinning of cortex.

• Accumulation of lipofuscin.

• Decline in cochlear endolymphatic potentials (EP).

• Elevation of compound action potential (CAP) thresholds of the auditory nerve.

• Asynchronous firing of the auditory nerve fibers

Synaptic loss at the level of the inner hair cells precedes actual hair cell loss.

Synaptopathy likely causes problems hearing in noise.

Age-related hearing loss begins much earlier especially at the higher frequencies although they are only clinically detected once the speech frequencies are involved. (Arvin, 2013)

Hidden Hearing Loss Cochlear synaptopathy

• “The cochlea uses more oxygen per proportion to size in the body than any other organ” (Nakashima et. al, 2003).

• “The auditory system depends quite heavily on the vascular system for nutrients and oxygen to maintain healthy neural function.” (Atcherson & Stoody, 2012).

• Moderate decreases in cochlear blood supply may have minimal consequences on tissue but produce hearing loss by disturbing cochlear physiology.

Blood supply and blood-labyrinth barrier (cat cochlea)

SCANNING ELECTRON MICROGRAPH

OF THE COCHLEAR VASCULATURE (rat)

Labyrinthine artery

(end artery)

Magnetic resonance imaging (MRI)

Reduction in both gray and white matter volumes

Functional Magnetic resonance imaging (fMRI)

Less activity in cortical auditory regions in older than younger adults (Cardin, 2016)

Magnetic resonance spectroscopy

Decrease in glutamate and N-acetyl aspartate levels. (Profant et al., 2013).

Decreased concentrations of gamma-aminobutyric acid (GABA). (Gao et al., 2015) & (Ren et al., 2018).

Increase in lactate levels. (Profant et al., 2013).

Neuroimaging Evidence

Cognitive Decline & Dementia

• ARHL is associated with age related cognitive decline. (Balkany, 2018).

• Memory and concentration both decline 30 – 40% faster in older adults who have hearing loss (Balkany, 2018).

• Older adults with hearing loss were more likely to develop dementia than older adults with normal hearing (Lin et al., 2011).

• National Institute on Aging suggested that sensory changes, hearing and vision impairments, are modifiable risk factors for dementia.

• Up to 9% of dementia cases in the world could potentially be prevented with hearing treatment and rehabilitation (Livingston et al., 2017).

• “Treatment of ARHL with hearing aids may attenuate cognitive decline” (Amieva et al., 2015).

The Chicken or The Egg!

Untreated hearing loss actually causes dementia (by depriving the brain of stimuli).

OR

Hearing loss is just one of the first signs of early-stage dementia.

(Balkany, 2018) & (Lin et al., 2011)

The risk of dementia increases proportionately with the degree of hearing loss

Theories

Auditory Deprivation: Use it or Lose it

“The sensory deprivation may cause de-afferentation and atrophy in the auditory system as well as subsequent reorganization, owing to long-term sensory deprivation.” (Panza et al., 2018).

The reduction of brain activity from processing sounds and comprehending speech may play a big factor in the development of dementia in many cases.

Speech recognition ability in unaided ears of

monaural hearing aid wearers decreases

significantly over time.

• The brain ability to change, remodel and reorganize for purpose of better ability to adapt to new situations (maturation, sensory deprivation, injury, and learning).

• Deprivation in one sensory modality (auditory) results in the recruitment of cortical resources of the deprived modality by intact sensory modalities (Visual).

• Training with cochlear implants and/or hearing aids prevent state of deprivation. (Niparko, 2009).

Neuroplasticity

HHIE-S

“HHIE-S questionnaire, is suitable in the screening for hearing loss in the elderly, given its high accuracy and user-friendly quality.” (Servidoni & Conterno, 2018).

“Screening for hearing impairment is a feasible and important task that can be routinely applied at the primary health care level for early detection of hearing loss among Saudi elderly subjects.” (Al-Musa, 2013).

Arabic HHIE-S is a valid and reliable questionnaire for the assessment of handicapping hearing impairment in Egyptian elderly patients (Weinstein et al., 2015).

Pure-tone sensitivity in the better ear was most highly correlated with the HHIE. (Ventry & Weinstein, 1983).

The sensitivity and specificity rates of this tool are approximately 70 to 80% for identifying hearing losses of moderate or greater degree. (audiology.org)

• Target group patients aged 60 years or over

• A total of 60 patients have been interviewed

• Age range 60-76

• Average age 65.5

A Cross Sectional Study

Preliminary Results

Goals:

Maintain physical and mental health

Reduce undesired effects of aging

Remain active and independent

“Many age-associated chronic diseases can be prevented, and even reversed, with the implementation of healthy lifestyle interventions.” (Fontana, 2009)

Modifiable risk factors:

smoking, unhealthy diet, noise exposure, physical inactivity,.....

Healthy Aging

• Oral administration of combination of antioxidant vitamins A, C, and E along with Mg++ (ACEMg), likely acting on free radicals and the stria vascularis delays the progression of hearing impairment associated with age in rats.

• ACEMg a known powerful cochlear vasodilator.

(Alvarado et al., 2018)

Healthy Diet

Hear Better, Live Better

• Better social connectivity related to reduced risk of subsequently developing dementia (Weinstein, 2018)

• Both the US and UK National Institute of Health (NIH) identified ARHL and social isolation as potential modifiable risk factors for dementia.