Cat ownership and schizophrenia: we know pets can have a profound impact on our lives, but can they influence whether we develop a mental health disorder?
Researchers link pet ownership with a variety of physical and mental health benefits, including decreased levels of cortisol (a hormone associated with stress), lower blood pressure, and improved mood. Animal-assisted therapy is beneficial for people with a variety of physical and mental health issues, including stress, anxiety, and pain.
Unfortunately, the news about associating with furry or feathered friends isn’t all positive.
A December 2023 meta-analysis suggests that owning a cat may put some people at increased risk for schizophrenia and related conditions.
This analysis, conducted by a team of researchers from the Queensland (Australia) Centre for Medical Health Research, included 17 studies from 11 nations published between Jan. 1, 1980, and May 30, 2023.
Here’s what the team reported:
“After adjusting for covariates, we found that individuals exposed to cats had approximately twice the odds of developing schizophrenia.”
Is a Parasite to Blame?
While the study revealed a strong association between cats and schizophrenia, the researchers effort didn’t assess causality.
In other words, they didn’t pose this research question:
What is it about owning or associating with a cat or cats that might increase likelihood of experiencing symptoms of schizophrenia or other signs of psychosis?
Others, however, did.
In a December 2023 article about the analysis, author Rebecca Dyer reported that one of the earlier investigations in this area identified a parasite called Toxoplasma gondii (T. gondii) as a possible culprit:
- The T. gondii parasite causes of toxoplasmosis, a common but potentially serious infection that often results from eating undercooked or contaminated meat or shellfish.
- Cat owners may be at increased risk of toxoplasmosis, as infected felines may pass the parasite to humans, primarily through their feces.
- If a cat owner contacts infected feces while cleaning a litter box, or if they’re bitten or scratched by a cat with toxoplasmosis, they can develop toxoplasmosis.
According to the Centers for Disease Control and Prevention (CDC), most people infected with T. gondii experience few to no symptoms. A healthy human immune system can prevent the parasite from causing serious problems.
The risk of more sever toxoplasmosis effects, which can include damage to the brain and several other organs, is highest among pregnant women and individuals with compromised immunity.
Can T. Gondii Cause Mental Illnesses?
A November 2020 study in the journal Parasitology investigated the possible link between T. gondii infection and several mental health disorders, with mixed results. This research involved a nationwide population-based study of Taiwanese adults, as well as a review of prior research.
Highlights of this report include:
- Participants with toxoplasmosis had “significantly higher risk” of developing anxiety, bipolar disorder, and depression.
- The researchers found “no significant differences” in schizophrenia risk when comparing Taiwanese adults with/without T. gondii infection.
- Prior studies in Finland, New Zealand, and The Netherlands found no strong association between T. gondii and schizophrenia.
- A study from Finland found a link between T. gondii and “psychotic-like symptoms,” but it did not associate the parasite with schizophrenia.
- Studies in The Czech Republic, Russia, China, and Denmark amassed “overwhelming evidence” connecting T. gondii with schizophrenia.
The research team concluded:
“Clearly, there is still much to be learned about associations between T. gondii and specific mental disorders.”
Can Early Exposure to Cats Raise a Person’s Risk?
Among the many efforts to establish a statistically significant association between cat ownership and an elevated risk of schizophrenia, some research focused on the age people begin to interact with feline family members.
In December 2019, the open access journal PLOS One published a study from Johns Hopkins School of Medicine that evaluated the impact of childhood exposure to dogs and cats on risk of developing bipolar disorder or schizophrenia later in life.
This study involved 1,371 participants, including 396 with schizophrenia, 381 with bipolar disorder, and 594 with neither. All participants were between the ages of 18-65 at baseline.
Findings from this research effort included:
- Having a dog as a household pet between birth and age 12 had no effect on rates of bipolar disorder, but was associated with a 25% lower risk of schizophrenia.
- Among participants with a household pet dog between birth and age 2, risk of schizophrenia was 50% lower than among the control group.
- First exposure to a household pet cat between the ages of 9-12 was associated with increased risk of schizophrenia.
- First exposure to a pet cat between birth and age 3 or between ages 9-12 was associated with increased risk of bipolar disorder.
This research team did not attempt to identify causal factors behind these correlations.
The PLOS One team emphasized that a wide range of additional influences – including family socioeconomic status and geographical location, parental education level, exposure to other animals, and the birth order of the study participants – may account for the variations in schizophrenia and bipolar disorder they uncovered.
What Is Schizophrenia?
Regardless of its cause, schizophrenia is a complex mental illness that can have a dramatic negative impact on the ability to live a full, productive, and satisfying life. However, people with schizophrenia can experience improvements if they receive proper treatment. Identifying the signs and symptoms of this disorder can help determine if someone in your life needs a professional assessment for schizophrenia.
Schizophrenia is characterized by disruptions in the ability to accurately perceive the environment and communicate with others. As defined in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), schizophrenia is associated with five types of symptoms:
Delusions:
Rigidly held beliefs with no basis in reality that are easy to disprove. Examples of delusions include believing that you receive coded messages through mass media or that you have special talents or magical abilities.
Hallucinations:
Perceptions of stimuli that don’t exist. The most common hallucinations are visual (seeing light patterns, objects, or people that aren’t there) and auditory (hearing music, voices, or other sounds that aren’t real).
Disorganized speech:
This may manifest in many ways, such as by rapidly jumping from topic to topic with no logical progression, responding to questions with rambling, unrelated responses, using words because of their sound rather than their meaning, and speaking in an indecipherable manner.
Grossly disorganized or catatonic behavior:
This type of symptom can involve acting with child-like silliness, behaving or dressing in a bizarre manner, and having difficulty with activities of daily living (ADLs) and other goal-directed tasks.
Negative symptoms:
Examples of negative symptoms include lack of facial expressiveness, speaking with a flat, monotone voice, inability to experience joy, and a lack of interest in associating with other people.
To receive a diagnosis for schizophrenia, a person must show at least two of the symptoms listed above, and one must be delusions, hallucinations, or disorganized speech.
Find Schizophrenia Treatment in Southern California
If someone that you care about shows signs of schizophrenia, your best first step is to consult with a qualified healthcare provider or a reputable mental health treatment center.
Once your loved one has completed a thorough assessment and received an accurate diagnosis, you can explore treatment options to find the most appropriate care for them.
In southern California, Crownview Psychiatric Institute offers life-affirming care for adults who have schizophrenia, schizoaffective disorder, and other complex mental health concerns. Our programming includes medication management, integrated therapies, educational opportunities, adjunct services, and full wraparound support, all provided in a welcoming and inclusive community-like environment.
To learn more or to schedule an assessment, please visit our Contact page or call us today.
Gianna Melendez
Jodie Dahl, CpHT