Project 467230

Age-related hearing loss, or presbycusis, is the most common health condition in the elderly after hypertension and arthritis. Presbycusis is thought to be associated with cognitive decline and may be a risk factor for dementia. Thus, long-term hearing deprivation could have an impact on cognitive performance by decreasing the quality of communication, which could lead to social isolation and depression, thus increasing the risk of dementia. An alternative explanation for the presbycusis-cognitive decline link could be the presence of a common mechanism. For example, reduced concentrations of gamma;-aminobutyric acid (GABA) have been observed in the auditory areas of individuals with presbycusis, which are correlated with the level of hearing loss. In cognitive terms, GABAergic concentrations in frontal areas are related to cognitive functioning in older adults. Thus, the overall age-related decrease in GABAergic concentrations may contribute to both cognitive decline and hearing loss in the aging individual, particularly in the frontal and auditory cortices. The primary objective of the proposed study is to determine whether the hearing loss observed in the presbycusis individual is associated with decreased GABAergic levels in the auditory cortex and whether it is accompanied by cognitive deficits related to GABAergic concentrations in the frontal cortex. Assessments of auditory and frontal functions in elderly people, in conjunction with data from magnetic resonance spectroscopy, will test the research hypotheses. The data from this research may have implications for the prevention, diagnosis, treatment, and care of dementia.