University of Arizona Study to Examine Growth Hormones and Cognitive Aging in Dogs

Researchers at the University of Arizona's College of Veterinary Medicine are investigating how growth hormones affect cognitive aging in dogs, particularly examining the role of insulin-like growth factor 1 (IGF-1). The study arises from the observation that larger dog breeds, like Great Danes, while having shorter lifespans, do not show expected earlier signs of cognitive decline compared to smaller breeds, such as Chihuahuas.

Evan MacLean, an associate professor of veterinary medicine, noted that although one might expect larger dogs to exhibit dementia at an earlier age, this pattern does not hold true. "The implication is kind of interesting: It means that big dogs may just die before they acquire any kind of cognitive dysfunction," MacLean stated.

The research project, named the Study of IGF-1, Neurocognitive Aging and Longevity (SIGNAL), will explore the influence of the growth hormone on cognitive aging in dogs. The study’s aim is to determine if dogs of similar sizes age differently based on varying levels of IGF-1. Funded by the American Kennel Club Canine Health Foundation, the study will include 75 medium-sized dogs from the local community. Researchers will measure hormone concentrations through blood samples and conduct cognitive assessments over two years.

MacLean, who also leads the Arizona Canine Cognition Center, emphasizes that dogs provide valuable insights into medical research due to their genetic diversity and the companionship they share with humans. He pointed out that while many studies are conducted on mice in controlled environments, dogs live in real-world conditions and receive quality medical care.

The exploration of IGF-1 was sparked by observations of aging disparities in dogs. Despite larger breeds typically being diagnosed with age-related diseases earlier, cognitive decline appears consistent across dog sizes. MacLean noted he identified this pattern through surveys filled out by dog owners for a 2022 paper.

The research will examine whether higher IGF-1 concentrations correlate with better cognitive performance in dogs. MacLean explained that while IGF-1 can lead to negative consequences like cancer, it also plays a role in brain health, potentially aiding neuron repair and growth. The study aims to clarify the relationship between IGF-1 levels and cognitive function, an area already recognized in human research regarding dementia risk.

Collaborating with MacLean on the project are U of A colleagues Emily Bray and Gene Alexander, as well as researchers from Arizona State University, Colorado State University, and Tufts University. The team is seeking participation from owners of dogs aged 10 to 13 years that weigh between 15 and 25 kilograms (33 to 55 pounds). Interested participants can contact the Arizona Canine Cognition Center for more details or to enroll.