User:DiefeiC/Hearing loss

Cognitive decline, cognitive impairment and dementia
Hearing loss is an increasing concern especially in aging populations, the prevalence of hearing loss increase about two-fold for each decade increase in age after age 40. While the secular trend might decrease individual level risk of developing hearing loss, the prevalence of hearing loss is expected to rise due to the aging population in the US. Another concern about aging process is cognitive decline, which may progress to mild cognitive impairment and eventually dementia. The association between hearing loss and cognitive decline has been studied in various research settings. Despite the variability in study design and protocols, the majority of these studies have found consistent association between age-related hearing loss and cognitive decline, cognitive impairment, and dementia. The association between age-related hearing loss and Alzheimer's disease was found to be nonsignificant, and this finding supports the hypothesis that hearing loss is associated with dementia independent of Alzheimer pathology. There are several hypothesis about the underlying causal mechanism for age-related hearing loss and cognitive decline. One hypothesis is that this association can be explained by common etiology or shared neurobiological pathology with decline in other physiological system. Another possible cognitive mechanism emphasize on individual's cognitive load. As people developing hearing loss in the process of aging, the cognitive load demanded by auditory perception increases, which may lead to change in brain structure and eventually to dementia. One other hypothesis suggests that the association between hearing loss and cognitive decline is mediated through various psychosocial factors, such as decrease in social contact and increase in social isolation. Findings on the association between hearing loss and dementia have significant public health implication, since about 9% of dementia cases can be attributed to hearing loss. Further studies are needed on distinguish whether hearing loss can be used as a biomarker for dementia diagnosis, or it is in fact a modifiable risk factor in dementia prevention.

Falls
Falls have important health implications, especially for an aging population where falls can lead to significant morbidity and mortality. Elderlies are particularly vulnerable to consequences of injuries caused by falls, because older individuals typically have greater bone fragility and poorer protective reflexes. Fall-related injury can also lead to burdens on financial system, as well as health care system. In literature, age-related hearing loss is found to be significantly associated with incident falls. There is also a potential dose-response relationship between hearing loss and falls---greater severity of hearing loss is associated with increased difficulties in postural control and increased prevalence of falls. The underlying causal mechanism between the association of hearing loss and falls is yet to be elucidated. There are several hypothesis which indicate that there might be a common process between decline in auditory system and increase in incident falls through some physiological, cognitive, and behavioral factors. These evidence suggest that treating hearing loss have a potential to increase health-related quality of life in older adults.

Depression
Depression is one of the leading causes of morbidity and mortality worldwide. In older adults, the suicide rate is higher than it is for younger adults, and more suicide cases are attributable to depression. Different studies have been done to investigate potential risk factors that can give rise to depression in later life. Some chronic diseases are found to be significantly associated with risk of developing depression, such as coronary heart disease, pulmonary disease, vision loss and hearing loss. Hearing loss can attribute to decrease in health-related quality of life, increase in social isolation and decline in social engagement, which are all risk factors for increased risk of developing depression symptoms. The association between hearing loss and depression suggests that there is an important public health implication for early diagnosis and treatment of hearing loss.