Dogs and humans that have dementia show similar brain patterns, new research finds

Photo: Associate Professor Julie Moreno and a student researcher examine canine brain data in Moreno’s CSU lab. (Photo by Joe Mendoza)

Julie Moreno is a neurotoxicologist and an assistant professor in the Prion Research Center. Her research centers on brain aging and the cellular mechanisms driving neurodegeneration. Moreno also serves as the associate director of CSU’s Brain Research Center. She investigates how misfolding proteins disrupt brain function and contribute to neuronal toxicity in neurodegenerative diseases.She earned her B.S. is biomedical science from Texas A&M University and her Ph.D. in cell and molecular biology at Colorado State University.

Media Release from Colorado State University Veterinary Teaching Hospital:

Dogs with a form of dementia known as canine cognitive dysfunction, or CCD, have telltale patterns in their brain tissue that are strikingly similar to those in humans with Alzheimer’s disease, according to new research that deepens the scientific connections between humans and dogs with age-associated neurodegenerative disorders.

“The dogs we analyzed with CCD – key areas of their brains look a lot like those same areas in humans with dementia,” said Julie Moreno, a neurotoxicologist and associate professor at Colorado State University, who co-authored the study. “This emphasizes the vital role dogs can play in helping us better understand cognitive diseases such as Alzheimer’s and will hopefully help us find new treatments in the future.”

These research findings reinforce a conclusion Moreno and her CSU veterinary colleagues have publicly discussed: that dogs with dementia may be observed and treated – and that the outcomes of that care can help inform medical care for people with one of society’s most difficult conditions. Alzheimer’s disease and related dementias in humans could become the second-leading cause of death in the U.S. in the next decade, according to the World Health Organization.

Scientists have long known that dogs, typically more than 8 years old, can suffer from CCD. Previously, researchers and clinicians have diagnosed these dogs via a series of behavioral tests and by looking for signs such as disorientation, altered social interactions, and functional decline. Clinicians use similar signs to identify humans suffering from dementia. Examining a brain post-mortem, however, offers a more definitive picture of the disease.

At the same time, scientists have also determined that abnormal clumps of proteins, known as plaques or tangles, build up in certain brain regions of people with Alzheimer’s disease, the most common form of dementia. They’ve learned that more prevalent plaques and tangles correspond to more advanced stages of the disease. Researchers have now shown for the first time that dogs with CCD develop these same irregular protein clumps in similar regions of their brain.

“No one had mapped this neuropathology in dogs before – that’s what we set out to do,” said co-author Dr. Caitlin Latimer, associate professor at the University of Washington School of Medicine. “Yes, we know that we see similarities in how an aging dog behaves and how an aging human might behave, but until we actually looked at the brain and tried to identify and quantify what was there, we didn’t have a true picture of the disease.”

For this new study, pet owners gave researchers consent to analyze the brains of 24 companion dogs. The analyses were conducted at either CSU or UW Medicine, and the results were published this week in the journal npj Dementia.

“I was surprised by how extensive the plaques were in some of these dogs,” Latimer said. “It’s exciting because it suggests these dogs could represent a model of the earliest stages of Alzheimer’s disease.”

CSU researchers were featured on 60 minutes for their translational work related to canines with CCD and humans with dementia.

A growing problem

Alzheimer’s disease and related dementias are challenging to research in part because 95% of human cases develop sporadically and later in life, making it difficult to study patients and to get a picture of how the disease develops. Understanding how dementia develops naturally in companion dogs presents scientists with research opportunities that do not exist with people, in part because dogs have much shorter lifespans.

“This work continues to lend credibility to the companion dog as an important model for studying Alzheimer’s and other similar diseases,” Moreno said. “This also opens the door for us to work with treatments in dogs that could eventually benefit people – we’re not far from that.”

Moreno’s research is an example of an expanding field known as translational medicine, a type of science that aims to improve human outcomes by first better understanding diseases that naturally occur in animals. CSU’s College of Veterinary Medicine and Biomedical Sciences is a worldwide leader in the field. A team including Moreno, CSU’s Dr. Stephanie McGrath, and others was recently featured on 60 Minutes for their work in this area.

Another benefit of working with companion dogs to study neurodegenerative disorders is that dogs live in the same environments as their owners. They drink the same water and breathe the same air – important details for researchers because the role that environmental factors play in how these diseases develop is a major unanswered question. (In a separate project, Moreno has partnered with another CSU researcher to examine whether water sources shared by dog owners and dogs correspond to canine cognitive decline.)

Working with companion dogs also presents research opportunities that do not exist when working with mice. Traditionally, Alzheimer’s research has been conducted on mice that do not develop the disease naturally, and treatments that have shown promise in rodents have not historically been successful in humans. Companion dogs could serve as a critical in-between step for scientists looking to develop successful therapies for Alzheimer’s disease while also limiting research on mice.

“This really helps make the case that these companion dogs are a good model for doing the kind of work that will have some translatability into humans,” Latimer said. “Dogs can be a kind of bridge and could also help us validate things we’re seeing in people.”

In addition to the brain analysis, researchers collected blood samples from about half of the dogs. The team plans to look for clues in these samples that might correspond to the analysis they later conducted on each brain. The idea is that it might eventually give scientists a better way to understand a patient’s level of cognitive dysfunction in real time.

Portions of this research led by Moreno and Latimer were also supported by the Dog Aging Project, a collaborative, long-term project among multiple universities that follows dogs throughout their lives with the goal of understanding how genetics, lifestyle, and environment impact their health as they age.

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