U of Arizona Researchers Investigate the Surprising Link Between Dog Size, Lifespan, and Cognitive Aging

Large dogs live shorter lives than smaller breeds, but a fascinating study at the University of Arizona College of Veterinary Medicine reveals their brains may age at the same rate. This surprising disconnect is prompting researchers to rethink our understanding of cognitive decline in canines – and potentially, in humans.

The Puzzle of Canine Cognitive Aging

Evan MacLean, associate professor of veterinary medicine, explains the conundrum: “Based on their different lifespans, you might expect large dogs like Great Danes to develop signs of dementia around 8 years old, but small dogs like Chihuahuas to have a later onset – somewhere in their teens. But that’s not what we find.” This observation suggests that larger dogs may simply succumb to other health issues before significant cognitive dysfunction sets in.

SIGNAL: A New Study on IGF-1 and Cognitive Health

To delve deeper into the biological mechanisms driving this phenomenon, MacLean is launching the Study of IGF‑1, Neurocognitive Aging and Longevity (SIGNAL). This project will investigate the role of the growth hormone IGF-1 in cognitive aging in dogs. The research aims to determine if dogs of similar size exhibit different aging patterns based on their IGF-1 levels.

Supported by the American Kennel Club Canine Health Foundation, SIGNAL will involve 75 medium-sized dogs from the local community. Researchers will track hormone concentrations through blood samples and conduct in-person cognitive assessments over two years.

Why Dogs? A Unique Model for Aging Research

MacLean, who also leads the Arizona Canine Cognition Center, believes dogs offer a valuable model for studying cognitive aging. Unlike laboratory mice, companion dogs are genetically diverse, share our environments, and receive consistent medical care throughout their lives. As the National Institute on Aging highlights, understanding aging in diverse species can provide crucial insights into human aging.

The Role of IGF-1: Growth, Aging, and Cognition

The investigation focuses on IGF-1 (insulin-like growth factor 1) because it’s known to influence body size variation in dogs, has been shown to affect aging in previous studies, and is linked to cognitive health in both humans and animals. Researchers are exploring whether IGF-1 prevents age-related decline rather than driving it.

MacLean hypothesizes, “Dogs with higher IGF-1 concentrations are going to perform better on our cognitive tasks.” IGF-1 may play a role in neuronal repair and even stimulate neural growth, potentially mitigating cognitive decline.

A Collaborative Effort

The SIGNAL study is a collaborative effort involving U of A colleagues Emily Bray, Gene Alexander, and researchers from Arizona State University, Colorado State University, and Tufts University.

How to Participate

The team is seeking owners of 10- to 13-year-old dogs weighing between 15 and 25 kilograms (33 to 55 pounds) to participate. Interested individuals can email the Arizona Canine Cognition Center or enroll online for more information.

The University of Arizona acknowledges the land and territories of Indigenous peoples.