Hearing loss (HL) in mid-life has been identified as a risk factor for cognitive decline.  It is unclear whether this relationship is due to the deprivation of auditory input, neurodegenerative processes, or a combination of both. Animal models are useful for investigating the underlying neural mechanisms of cognitive decline as they can control for confounding factors that may arise in human studies. However, most animal studies investigating HL and cognition use young animals and often exclude females.

Methods: We used middle-aged guinea pigs of both sexes to investigate whether 8 weeks of auditory deprivation due to conductive HL caused spatial learning and memory impairments. Forty guinea pigs (20 M, 20 F, ~12 months) were tested in the Morris Water Maze (MWM) to assess baseline spatial learning and memory. In 20 of these animals (10 M, 10 F) the ear canal was plugged and 8 weeks later, animals were again assessed in MWM. 

Key Findings: No deficits in spatial learning or memory were observed in either sex.  HL caused a small decline in body weight suggesting some stress associated with conductive HL, although adrenal/body weight did not change.

Conclusion: Our data suggest that auditory input deprivation alone does not affect spatial cognition in middle-age, in line with recent human data suggesting that additional risk factors need to be present.