Age-related cognitive impairments in domestic cats naturally infected with Feline Immunodeficiency Virus (FIV)

Background: Age-related dementia has been documented in domestic cats; however, its interaction with naturally occurring feline immunodeficiency virus (FIV) infection has been investigated only minimally. Methods: Visuospatial working memory (VSWM) and problem-solving (PS) ability were evaluated in FIV-infected (n=37) and control cats (n=39) using two cognitive tasks tested serially, which assessed the ability of cats to locate a baited container after a set delay, then evaluated the capability of the cats to manipulate the container to obtain the food within a time limit. Cats were categorized using 7-years-old as a cut-off to determine age-related differences. Relationship between cognitive performance and FIV viral load was investigated using real-time PCR Cycle Threshold (Ct) values. Results: Age significantly affected VSWM and PS ability. Younger cats had better VSWM performance and PS ability compared to the older cats with the same FIV status. There was no difference between younger FIV-positive and negative cats in either part of the task. Moreover, while older FIV-positive cats had significantly worse VSWM than older FIV-negative cats, no differences were found in PS ability. Additionally, Ct values predicted VSWM but not PS ability. Conclusion: Age-related cognitive impairments and FIV-infection appear synergetic, causing greater cognitive deficits in older FIV-infected cats.