Age-related hearing loss
Age-related hearing loss, or presbycusis, is a common, gradual decline in hearing ability that typically affects both ears as a person ages.
Overview
Age-related hearing loss (also known as presbycusis) is a decrease in hearing ability that happens with age. In most cases, the hearing loss affects both ears. It can begin as early as a person's thirties or forties and worsens gradually over time.
The condition first affects the ability to hear high-frequency sounds, such as speech. Affected people find it increasingly difficult to understand what others are saying, particularly when there is background noise. Because the hearing loss is gradual, many people do not realize they cannot hear as well as they used to, often turning up the television volume or speaking louder without being aware of it.
As the condition worsens, it affects more frequencies of sound. Determining where a sound is coming from (localization) and identifying its source become more challenging. Some individuals also experience a ringing sensation in the ears (tinnitus) or dizziness and problems with balance (presbystasis).
Age-related hearing loss can impact quality of life by affecting communication, which may contribute to social isolation, depression, and loss of self-esteem. It also creates safety issues if individuals become unable to hear smoke alarms, car horns, and other warning sounds.
Frequency
Age-related hearing loss is one of the most common health conditions affecting older adults, impacting tens of millions of people worldwide. In the United States, an estimated one-third of people over age 65, and half of those over 85, have some hearing loss.
Causes & Risk Factors
The causes of age-related hearing loss are complex, resulting from a combination of genetic, environmental, and lifestyle factors. It is most commonly associated with changes in the inner ear, where sound waves are converted to nerve impulses, though it can also involve nerve pathways in the brain or changes in the eardrum and middle ear bones.
- Genetic Factors: Inherited variations in multiple genes influence the onset and severity of the condition. Some genes are critical for the structure or function of the inner ear.
- Mitochondrial DNA (mtDNA): Changes in mtDNA are among the best-studied genetic factors. As people age, mtDNA accumulates damaging mutations due to reactive oxygen species. Cells with high energy demands, such as those in the inner ear, are particularly sensitive to this damage, which can lead to cell malfunction and death.
- Environmental and Lifestyle Factors: Long-term exposure to loud noise, smoking, and exposure to heavy metals like mercury or lead contribute to the condition.
- Medications and Health Conditions: Certain medications, such as specific antibiotics and chemotherapy drugs, can damage inner ear cells. Additionally, health conditions common in older adults, such as heart disease and diabetes, can influence hearing loss.
Associated Genes
- APOE, CDH23, KCNQ4, MTHFR, MYO7A, SLC26A4, and mitochondrial DNA.
- Additional genes: EDN1, ESRRG, GIPC3, GRHL2, GRM7, GRM8, MYO6, NAT2, and UCP2.
Inheritance
Age-related hearing loss typically does not have a clear pattern of inheritance. While many affected individuals report a family history, the condition is so common in the general population that it can be difficult to determine if it is inherited within a specific family. However, having close relatives with severe age-related hearing loss is associated with an increased risk of developing the condition.