Age‐related cognitive impairments in domestic cats naturally infected with feline immunodeficiency virus

Abstract

Background Age‐related dementia has been documented in domestic cats; however, its interaction with naturally occurring feline immunodeficiency virus (FIV) infection has been investigated 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 remember the location of 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 of age as a cut‐off to determine age‐related differences. The 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 older cats with the same FIV status. There was no difference between younger FIV‐positive and negative cats in either part of the task. 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.

Understanding the impact of feline immunodeficiency virus on cats' cognitive performance

“…cats had significantly worse VSWM than older FIV-negative cats, no differences were found in PS ability. 15 These findings suggest that FIV affects cats' memory more than their motor ability, although it is important to note the authors' caveat that the PS test used in this study may not have been sensitive enough to capture variation in PS due to ageing or FIV. However, unlike other species, cats do not appear to prefer working for food versus accessing freely available food, 17 so it may be difficult to motivate them in more extensive PS tests.…”

“…In a study summarised on p 31 of this issue of Vet Record, Azadian and Gunn-Moore 15 sought to address this knowledge gap by comparing the visuospatial working memory (VSWM) and problem-solving (PS) ability (Fig 1 ) of FIV-infected and uninfected cats from two age groups: those under seven years old and those aged seven years or older. This comparison allowed them to examine how age and FIV infection interact to predict cognitive performance.…”

“…Furthermore, the oldest infected and uninfected cats were only 10.2 and 12.8 years old, respectively. 15 Thus, the Azadian and Gunn-Moore's 'older' group represented mature but not senior or geriatric cats. Although deficits in spatial memory have been identified in cats as young as six to eight years, 14 further work is needed to determine whether the differences in cognitive decline become more pronounced as cats continue to age.…”

Clinicopathological and Epidemiological Findings in Pet Cats Naturally Infected with Feline Immunodeficiency Virus (FIV) in Australia

“…Health status (i.e., ‘healthy’ vs. ‘sick’) was retrospectively assigned by the primary author (C.C.) based on both the cat’s clinical condition at the time of testing, and the reason for testing, as previously described [ 21 , 25 ]. Cats were classified as ‘apparently healthy’ if FIV testing was performed as part of a routine health check, including admission to the hospital shelter, pre-anesthetic testing prior to sedation or general anesthesia for routine preventative procedures (e.g., neutering, treatment of cat fight wounds or dental disease).…”

“…Experimentally and naturally FIV-infected cats may show an increased susceptibility to opportunistic infections and immune dysregulation [ 15 , 18 , 19 ]. This can manifest clinically as oral cavity disease [ 4 , 20 ], renal disease [ 21 , 22 ], neurological disease and neurocognitive dysfunction [ 23 , 24 , 25 ], hematological abnormalities [ 1 , 19 , 26 ] and certain neoplasms [ 27 , 28 ]. In Australia, an association with FIV status has been found in cats with clinical signs of illness [ 5 , 29 ], and in cats presenting with periodontal disease, chronic kidney disease and lymphoma [ 21 , 30 , 31 , 32 ].…”