Can animals have schizophrenia
What Can Animals Tell Us About Mental Illnesses?
How can you tell if a mouse has schizophrenia?
I get this question a lot. You see, in my research lab, I study the brains of mice engineered to carry a genetic mutation that increases the risk for schizophrenia in humans. So, when I meet new people, the first question I get is the usual, so, what do you do? And the second question... well, now you know.
I used to respond with a smart retort, like, ask a mouse psychiatrist. But it turns out it is a great question, for two reasons. First, it is an opportunity to talk about my science, which I love to do (almost as much as I love doing the science in the first place!); second, the answer is simultaneously obvious and nuanced, and important for our field to get right.
The obvious answer
Mice do not have schizophrenia.
Or any other mental illness. The human brain is a complex organ, dizzyingly complex, and quite different from the mouse brain in many ways. These differences definitively preclude us from re-creating a mental illness in its totality in mice. One small fact: people with schizophrenia have changes in the function of the dorsolateral prefrontal cortex, a piece of the brain that sits roughly above the temples. Mice dont have a well-defined dorsolateral prefrontal cortex, above their temples or anywhere else!
Of course, there are a lot of other differences between mice and people besides just the presence of a dorsolateral prefrontal cortex different genes, molecules, cells, circuits, and behaviors. Indeed, the differences in behaviors are particularly challenging and not just because mice cant tell us if they hear voices! Variations in how human patients express emotion, perform cognitive tasks, seek out rewards, avoid punishments, and interact with other people (including their doctors and therapists) are how we recognize and categorize mental illnesses. The profound difference in these behaviors between mice and people prevents the straightforward mapping of psychiatric syndromes across species.
Take emotional expression, for example. In people, facial expressions reflect their inner emotional experience smiles for happiness, frowns for sadness, furrowed brows for anger, etc. Not so in mice. But we can recognize various states that seem to mirror these human emotions by observing other behaviors in mice their movement patterns, the tone of their vocalizations, the repetitiveness of their grooming, and their bowel movements and eating habits. Accordingly, scientists have used these behaviors to try to model human disorders in mice. For example, scientists have studied overgrooming as a potential model of obsessive-compulsive disorder and avoidance of food in a brightly lit open arena as a model of anxiety, etc.
None of these models can accurately reflect the human condition. For example, anxiety in humans is much more than avoidance of food in a brightly lit area anxiety can be accompanied by changes in energy, sleep, and other behaviors. Similarly, individuals with mental illnesses such as schizophrenia typically suffer from a range of symptoms, including episodic hallucinations and delusions, but also more enduring social and cognitive dysfunction. No mouse model of schizophrenia can accurately reproduce all these features, nor should we expect one to do so. Mice are not people. Mice do not have schizophrenia or anxiety.
The nuance
Nonetheless, mice (and other species) can help us understand and develop treatments for schizophrenia, anxiety, and other mental illnesses. How? By teaching us about molecules, cells, circuits, and systems of the brain; how they work; and how they produce behavior. We can then use that information to identify better targets for treating impairments or symptoms associated with mental illnesses.
One example: in my research, I dont study a mouse model of schizophrenia (remember, there is no such thing). Instead, I study how certain genetic mutations increase the risk of schizophrenia and how we might use that understanding to develop new treatments. So, when I was starting my career, I teamed up with colleagues at Columbia University (Drs. Joseph Gogos, M.D., Ph.D., and Maria Karayiorgou, M.D., among others) to try to study the effect of one of these mutations, the 22q11.2 microdeletiona deletion of more than 20 genes that results in a neurodevelopmental syndrome. About 30% of people with this microdeletion will develop schizophrenia, making it one of the strongest genetic risk factors for the disease.
Several groups, including those led by Drs. Gogos and Karayiorgou, engineered the genome of mice to create a similar deletion. But they didnt create mice with schizophrenia. They created mice that could be used to study the effects of this microdeletion on brain development and function. Before I came along, they had already demonstrated significant effects of the microdeletion on molecular function, neural development, and working memory. My lab worked with theirs to demonstrate that these effects could all be linked together by changes in the function of a particular circuit involving the hippocampus and prefrontal cortex, two brain regions often implicated in schizophrenia. We also showed that targeting one particular molecular mechanism a protein called a kinase that is important for neurons as they develop reversed the effects on neurodevelopment, thereby rescuing the circuit and behavioral changes. We continue to work together to try to figure out whether this molecular mechanism might be a good therapeutic target to help people with the microdeletion and/or others with schizophrenia.
This is the approach we use not only in my lab but throughout the NIMH portfolio: carefully choosing animal models to explore the mechanisms underlying biological processes relevant for mental illnesses and then using this mechanistic knowledge to begin the challenging process of developing novel interventions. As Ive written about recently, this approach can work. But it requires careful experimental design to ensure that the questions being asked can be properly answered in an animal.
This last point is really important to consider. We have an obligation to carefully consider the need for animal studies, for both ethical and scientific reasons. Ethically, we must remember that animals are deserving of being treated with respect and care for their well-being. Scientifically, given the difficulty of translating across species, if there is knowledge that can be gained safely and ethically from healthy humans and individuals with mental illnesses, we should study them instead of animals. But to understand the full complexity of the brain--particularly how the circuits of the brain drive behavior, and the role of molecular and cellular processes in the development and function of those circuits animals will continue to play a crucial role. We must, therefore, ensure that they are used appropriately to answer those questions that would be impossible or unsafe to answer using human subjects.
Can Animals Get Schizophrenia, or Is It Unique to Humans?
Animals can suffer from many of the same mental illnesses that humans do, such as anxiety, depression, obsessive compulsive disorder (OCD) and post-traumatic stress disorder (PTSD). But theres one mental illness that, at least as far as we can tell, that animals dont get: schizophrenia.
Schizophrenia and Animals
Admittedly, it would be difficult to know if an animal were suffering from schizophrenia. The National Library of Medicine describes the symptoms of schizophrenia as including hallucinations, most commonly auditory but often involving hallucinatory visions, smells or even tastes, as well. In addition, schizophrenia can cause delusions, such as thinking that youre George Washington or Napoleon, that youre the focus of an evil plot or even that youre being controlled by beings from other planets or dimensions.
If something like that were going on in the mind of, say, your dog, how would you even know? Meanwhile, cats certainly appear to hear voices that we cant, but unfortunately, they cant tell us about them.
But despite having limited access to the inner lives of other animals, theres good reason to think that schizophrenia is unique to humans, and the evidence is in the human genome.
Read More: Were Not Alone: Animals Suffer From Mental Health Issues Too
Why Do Humans Get Schizophrenia?
Schizophrenia tends to run in families and has long been understood to be substantially influenced by genetics. But no single gene seems to be responsible for the malady. A Nature study published in 2022 fingered 10 particular genes in which alterations can lead to schizophrenia. A subsequent study on a larger, more diverse population reinforced these findings, adding three more genes to the mix.
Schizophrenia-linked genes appear in an area of the genome that changed rapidly during human evolution. This period of rapid change began after humans branched off from chimpanzees, making the results of the changes unique to humans.
These gene regions are called HARs, short for human accelerated regions. HARs are involved in modulating the expression of other genes and, among other things, seem to play a role in the cognitive and behavioral diversity among humans.
Read More: Thought Broadcasting: When Your Thoughts Are No Longer Your Own
The Evolution of Schizophrenia
A review study on the research to date on HARs, and their role in mental illness, was published last year in the International Journal of Molecular Sciences. In that study, researchers Maria Guardiola-Ripoll and Mar Fatj-Vilas explain that the expansion of the cortex in human evolution is thought to have contributed to the development in our species of more complex neuronal structures.
This uniquely human brain organization is what makes our higher cognitive abilities possible; capacities such as memory and attention, our knack for abstract thinking, our ability to use language and social cognition. Guardiola-Ripoll and Fatj-Vilas describe these as core traits of humankind and point out that they are often the very things that are compromised in schizophrenia.
Read More: Why Schizophrenia is Different for Women
So Why Don't Animals Get Schizophrenia?
Theres a lot more work to be done before we fully understand the evolutionary background of the genetics behind schizophrenia, and how specific genes influence the onset and nature of the disease. Such work aims to better our understanding of the influence genes and gene expression have over mental illnesses, and ultimately lead to more effective treatments.
Meanwhile, for those of us simply wondering why animals dont get schizophrenia, researchers can offer a possible answer: Other animals just dont have the right genes for it.
Still, for the human population as a species, schizophrenia (and other forms of mental illness) may be the price we pay for that complex cortical architecture and the uniquely human cognitive abilities that come with it.
Read More: What To Do If Your Pet Is Struggling With Anxiety
Can Cats Have Schizophrenia?
If you've ever experienced a cat's abrupt behavioral change from cuddling and sweet to hissing and clawing, you likely have wondered about the root cause. What is driving these behavioral changes? This sudden shift can be surprising and confusing for some cat parents. You might even have asked yourself, can cats have schizophrenia?
In people, schizophrenia is a mental disorder that causes problems in a person's relationship between thought, emotion and behavior, leading to apparent shifts in personalities, violent behavior when threatened and hallucinations. But, can cats be schizophrenic? Read on to learn whether cats can have schizophrenia or if their behavior is indicative of something else.
Can Cats Have Schizophrenia?
If you've spent any time around furry feline friends, you know that sometimes their cat behavior may warrant a visit to Google and in some cases, you may be tempted to search, "Can cats be schizophrenic?" Cats can sometimes appear to have rapid shifts in their personalities, from friendly and purring to aggressive and biting. They can also freeze and stare blankly at walls or ceilings. However, there are no studies or research that proves cats have schizophrenia; we simply cannot get inside their minds enough to know.
But, there is an unexplained disorder in cats called feline hyperesthesia syndrome (FHS) that can mimic a lot of the signs of schizophrenia. For example:
- FHS can affect both male and female cats equally, and it usually starts early in life.
- FHS can cause cats to abruptly shift from happy to upset without apparent provocation.
- Cats with FHS can display freezing behavior.
- Genetics seem to be at play in both human schizophrenics and cats with FHS. While FHS can be seen in all cat breeds, the Siamese, Abyssinian, Burmese and Himalayan breeds appear to be predisposed to FHS.
- FHS may also be a seizure disorder in cats.
No one knows what causes FHS in cats. FHS could be a behavioral problem, seizure disorder or sensory neuropathy that causes the cat pain, or it could be a combination of all three. What is known is that cats who are nervous or irritable seem to be at higher risk for FHS.
Clinical Signs of Feline Hyperesthesia Syndrome
In addition to the behaviors listed above, a cat may be suffering from FHS if the following clinical signs are displayed, especially after petting a cat with FHS:
- Episodes of skin twitching down the back
- Skin twitching accompanied by violent tail swishing
- Unexpected growling or aggressive vocalization
- Dilated pupils
- Sudden unprovoked attacks
In between episodes, a cat with FHS appears completely fine, and physical examination of the cat by a veterinarian is usually normal. FHS is treated by minimizing the cat's stress in the household as stress tends to trigger episodes. Environmental enrichment is often enough by itself to successfully reduce episodes, according to the Drake Center for Veterinary Care. In severe cases, several medications have been used successfully by vets to treat FHS, including gabapentin, SSRIs like fluoxetine, tricyclic antidepressants, benzodiazepines and anti-seizure medications. Your vet will be your best resource to determine the best treatment for your cat.
Behaviors Mistaken for FHS in Cats
Other medical conditions can be confused for FHS, and if you don't know what's going on, you might find yourself asking, "Can cats have schizophrenia in some way?" Here is a short list of medical conditions that can mimic the signs of FHS or seeming schizophrenia in cats:
- Redirected aggression: Cats can seem to explode with aggression or become more irritable for no clear reason, but it could be redirected aggression. Common in cats, redirected aggression is when a cat sees, smells or hears something scary or over-stimulating, and as a result, the cat redirects their frustration, aggression or fear onto whoever is closest, as noted by the International Association of Animal Behavior Consultants.
- Skin disease: Anything that causes a cat to be itchy, like fleas, mites, ringworm or allergies, can cause skin rippling and irritability that can mimic the signs of FHS.
- Back pain: Anything that causes back pain, including arthritis, bulging discs or other spinal disease, can appear to be FHS.
- Hyperthyroidism: Hyperthyroidism is a hormonal condition in cats that causes abnormally high levels of thyroid hormone. This causes behavioral changes in cats, including yowling, pacing, increased aggression, rippling skin along the back and changes in sleep and appetite that are similar to the signs of FHS in cats.
If you notice any changes in your cat that could potentially be feline hyperesthesia syndrome, or if your cat's behavior has you wondering can cats have schizophrenia, then it's time to call your local vet. They will be able to help you assess the situation, get your pet the treatment and relief they need, and hopefully spare your fingers and hands from grumpy claws and teeth!
Contributor Bio
Dr. Sarah Wooten
A 2002 graduate of UC Davis School of Veterinary Medicine, Dr. Sarah Wooten is a well known international speaker in the veterinary and animal health care spaces. She has 10 years experience in public speaking and media work, and writes for a large number of online and print animal health publications. Dr. Wooten has spoken in the veterinary education space for 5 years, and speaks on leadership, client communication, and personal development. Dr. Wooten is also a certified veterinary journalist, a member of the AVMA, and has 16 years experience in small animal veterinary practice. In addition to being a speaker, author, veterinarian, and co-creator of the wildly popular card game 'Vets Against Insanity', she co-owns Elevated Eateries Restaurant group in Greeley with her husband of 22 years, and together they are raising 3 slightly feral mini-humans. When it is time to play, she can be found skiing in Colorado or diving with sharks in the Caribbean.
Go big...or go home. To learn more, visit drsarahwooten.com.
