Distinct changes in brain metabolism in patients with dementia and hearing loss

Area of Science:

• Neuroscience
• Gerontology
• Medical Imaging

Background:

• Hearing loss (HL) is increasingly associated with dementia, but the underlying brain mechanisms are not fully understood.
• Understanding these links is crucial for diagnosing and managing cognitive decline.

Purpose of the Study:

• To investigate brain metabolism changes in patients with hearing loss and different types of dementia.
• To identify specific metabolic patterns associated with Alzheimer's disease-related cognitive impairment (ADCI), Lewy body disease-related cognitive impairment (LBDCI), and vascular cognitive impairment.

Main Methods:

• 108 patients with cognitive impairment (CI) and HL underwent audiometry, neuropsychological testing, MRI, and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET).
• A control group of 27 individuals without CI or HL was included.
• Multivariable regression analysis was used to correlate brain metabolism with specific dementia types.

Main Results:

• ADCI was linked to hypometabolism in the right superior temporal gyrus (STG), right middle temporal gyrus (MTG), and bilateral medial temporal lobe.
• LBDCI showed hypermetabolism, while vascular CI exhibited hypometabolism in the ascending auditory pathway.
• In ADCI, HL severity correlated positively with right MTG metabolism; in LBDCI, HL correlated negatively with right STG metabolism.

Conclusions:

• Different dementia types manifest unique brain metabolic alterations in individuals with hearing loss.
• These findings highlight the complex interplay between sensory deficits and neurodegenerative processes.