The domestication of modern-day animals has led to the common practice of keeping household animal companions around the world. In the United States, it was reported that about 75% of U.S. households owned some kind of pet.¹ The estimated number of dogs and cats kept as pets worldwide is in the hundreds of millions.² There are many reasons why someone might want to have an animal companion, and it is not uncommon for animals to be trained to respond to specific health disorders. While the ability of pets to accommodate human health issues is not debated, the non-pharmacological and preventative treatment capability of pets is an underrepresented field of study with varying potential in the success of treating neurological disorders.

Conventional medicine relies on multiple different pharmacological treatment options targeted towards different neurological mechanisms in an effort to reduce the severity and maintain healthy neurological function. For example, one treatment for Alzheimer’s disease is an inhibitor targeting the breakdown of acetylcholinesterase.³ This category of drug called cholinesterase inhibitors prevent the breakdown of acetylcholine by this enzyme in the brain, possibly improving the symptoms of Alzheimer’s disease. This approach is very direct, altering levels of neurotransmitters available in order to improve communication between nerve cells, an observed complication in Alzheimer’s patients. While new forms of pharmacological treatments are constantly being developed, it is practical to investigate other avenues of research that might alleviate symptoms of neurological disorders. Such non-pharmacological treatments operate on different aspects of the mind, acting as placebos that reduce pain from ailments or even used in conjunction with medication to improve pharmacotherapy outcomes.⁴

The mechanisms by which neurological disorders operate are diverse, and developing treatments to heal or alleviate symptoms is difficult when the targets of these treatments are on the cellular level. Treatments such as antidepressants target systems within the brain that are involved in regulating levels and distribution of neurotransmitters. Serotonin, for example, aims to treat depression and anxiety. Stress is another behavior that when exaggerated can have lasting effects on health as well as being an indicator of existing neurological issues. These issues are often targeted with drugs but are affected by other factors which include diet, lifestyle, and of recent suggestion, animal accompaniment, which could serve as an alternative to existing neurological therapies.

The method of utilizing animals as therapeutic medicine is not unheard of. Animal-assisted therapy (AAT) is a common practice used to rehabilitate patients with acute or chronic diseases. Common animals utilized for this therapy are cats, dogs, and horses, but other non-conventional animals like lizards and birds can also provide the same quality of therapy.⁵ This is becoming increasingly common among facilities caring for geriatric individuals, with studies suggesting that emersion with dogs among elderly individuals results in patients with dementia having plateaued levels of agitation/aggression.⁶ Results from another study also suggest that AAT may influence the progression of neuropsychiatric symptoms.⁷ The routine of AAT and similar therapeutic treatments consists of visitation by the animal over varying frequencies and requires different temperament and obedience training before an animal can participate. This introduces hurdles of accessibility which are necessary for the strict control required by the animal to perform in varying situations. In a household setting, these specifications vary according to the owner’s and environment’s requirements, making it easier to have human-animal interactions on a more frequent basis.

Health Benefits

Epinephrine and norepinephrine act as neurotransmitters and hormones involved in maintaining homeostasis in the autonomic nervous system, influencing the body’s response to stress and metabolism.⁸ An imbalance of these neurotransmitters can cause a variety of issues from anxiety and depression to post-traumatic stress and attention deficit hyperactivity disorder (ADHD). Studies done on adults hospitalized with heart failure show less anxiety, lower blood pressure, and lower epinephrine and norepinephrine levels after a visitation from dogs.⁹ Additional options for controlling levels of these chemicals are promising for those who are impacted by neurological issues lasting throughout their life, rather than within short-term hospital visits. On the other hand, it is important to state that some neurological disorders result from low levels of norepinephrine activity, and individuals might not benefit from human-animal interactions as a result.

So, what are the health outcomes of consistent exposure and interaction with companion animals? In short, it depends on who you ask. While being a relatively shallow research pool, preliminary results suggest that there are many general health factors that can benefit from daily interactions with animals.¹⁰ Some studies report human-animal interactions to have effects on multiple mechanisms related to physiological responses to stress, anxiety, and depression.¹¹ In children between ages 7 and 12, it was reported that groups interacting with a dog reflected lower cortisol levels, showing a significant connection to having physical contact with the animal.¹² This research could provide translational non-pharmacological therapies for neurological deficits caused by diseases like Cushing’s syndrome, also called hypercortisolism, resulting from chronic exposure of the body to high cortisol levels.¹³ While not a viable “cure,” an individual with Cushing’s syndrome might benefit from daily interaction with a pet in conjunction with pharmacological treatments, reducing neurological effects leading to muscle weakness and memory problems.¹⁴ Chronic stress is also related to unstable cortisol levels, and while short-lived periods of stress are normal, chronic exposure can lead to neurological damage. Specifically, this imbalance can contribute to interruptions in physiological processes within the autonomic nervous system, affecting cognitive abilities.¹⁵

Oxytocin acts as a neuropeptide hormone involved in socialization, and stress relief, and is implicated in many psychiatric disorders like schizophrenia and anxiety disorders.¹⁶ While research is limited on the effect human-animal interactions have on oxytocin levels, it is suggested to be responsible for the calming effect produced by these interactions. In a study of 18 adults, decreased cortisol levels and an increase in oxytocin and dopamine levels were reported after petting a dog.¹⁷ In another study, female dog owners were seen to have increased serum oxytocin levels when interacting with their dog, however, male dog owners were not significantly impacted.¹⁸ In clinical interviews with the presence of a dog, adult patients with acute schizophrenia showed decreased state anxiety after the interview.¹⁹ Additionally, a study that compared AAT with a control group in adult psychiatric inpatients from ages 20-66, reported patients who received AAT were more sociable and interactive with other patients.²⁰ Not only were human-animal interaction observed to reduce behaviors associated with neurological disorders, but these studies also suggest that these interactions can further rehabilitate productive social behaviors that are commonly hindered by these disorders. While not evaluated in this study, it is possible that these improvements in social behaviors and responses to social stimuli could be caused by the human-animal interaction’s influence on oxytocin levels.

Besides direct involvement in the improvement of hormone levels and neural mechanisms, the quality of life of individuals with neurological disorders can be improved through the indirect effect of having a pet. In a study observing adults with memory-impairment, physical exercise over a period of six months reflected an improvement in cognitive ability over an 18-month follow-up period.²¹ Owning an animal requiring consistent exercise to maintain its health, like medium to large-sized dogs, requires participation and maintenance to be aware of the animal’s physical health. It is also shown that dog owners have an increased likelihood of being physically active, compared to cat owners showing a decreased likelihood of being active.²² While research in animal ownership contributing to health benefits is non-extensive, findings like this point to future directions of study, in this case discriminating between different animal companion types and suggesting that characteristics of the animal might influence their therapeutic success.

In a study monitoring patients with Alzheimer’s disease, improvement of their condition by increased food intake, weight, and a decreased need for nutritional supplements resulted after an introduction of an aquarium.²³ Non-conventional companion animals like fish have been less studied compared to cats and dogs which are commonly used as trained support animals. Still, it is suggested that non-conventional animals can substitute traditional pets, with one study reporting a significant increase in relaxation and a decrease in loneliness, factors that could contribute to the progression of neurological disease and disorders.²⁴

Risks and Obstacles

Although initial findings on the beneficial effects of animal companionship on neurological health seem significant, the practicality of initiating and maintaining this method of therapy is worth explaining. Issues with having a pet involve a multitude of financial, logistic, and health concerns. Of the more immediate and impactful of these is the concern of owning a pet leading to negative health outcomes. Rather than the simplicity of drug administration usually requiring short-term interactions with environmental exposure, owning a pet is a commitment that involves constant interaction with a living organism that can be a host to many zoonotic diseases. With the right access to medical care and knowledge, this can be avoided, however, it’s important to acknowledge those who might be at risk of close interactions with living organisms. People who have compromised immune systems, including children, pregnant individuals, and those with autoimmune disorders might take additional steps toward reducing the risk of exposure to illness. This might seem straightforward, but those with neurological or psychiatric disorders could be unaware of underlying issues that have developed and affected their immune resilience to diseases like toxoplasmosis, originating in the feces of an infected animal that could be spread through routine cleaning and animal care.²⁵

Not all research on the therapeutic effects of human-animal interaction shows promise. While neurological disorders like Alzheimer’s disease and dementia saw positive influence after exposure to an animal, children between the ages of 4-12 with cerebral palsy had no significant effect on functioning, health, or quality of life after a 10-week horse riding program.²⁶ This not only brings to light the limitations animal therapy might have but also the importance of specificity when treating neurological conditions. In this particular case, it might be of interest to explore and compare therapeutic effects on multiple neurological disorders using the same therapeutic animal method. Research findings that contradict previous conclusions like this one can lead to a more detailed explanation of the mechanisms behind them, hopefully improving our understanding of this field further.

Financial factors limit access to medical care, and those unable to afford extended medical care may also not be able to afford the financial commitment of an animal. And while everyone deserves the right to receive healthcare personalized to their condition, this informal version of animal-assisted therapy still might not be an option for those having difficulty affording basic medical care.

Neurological diseases and disorders affect many individuals, limiting their ability to communicate, interact with their environment, and have a high quality of life. To expand on society’s ability to treat and manage neurological conditions, it is important to recognize non-typical methods of therapy. Owning a pet can be a multifaceted relationship, providing direct and indirect therapeutic effects to neurological disorders/diseases and overall health. While there is a lack of critical evidence proving the direct benefits of pet ownership in improving neurological disorders, there is much to gain from studies demonstrating the influence human-animal interactions have on levels of neurotransmitters like epinephrine and neuropeptides like oxytocin, possibly playing a role in remedying dysfunction in social-behavior capacities and the phycological responses of increased stress, anxiety, and depression. While described as a viable non-pharmacological treatment option, pet ownership is not possible to the same extent for everyone, and financial, biological, and logistical limitations contribute to preventing ease of access to animal companions. Although the risks of owning an animal companion might be inconvenient and hazardous in extreme cases to individuals with compromised immune systems, they can be significantly reduced through proper veterinary care, hygiene practices, and general caution. The indirect influence of human-animal interactions including improvement of social behaviors and encouraging physical activity are also suggestions of the diversity in which animals might provide relief through maintaining healthy lifestyle practices in individuals with neurological disorders.