Infections, Mental Health, & How To Stay Healthy


Infections from viruses or bacteria can be a root cause of depression, schizophrenia and other mental health issues. Do you know about this trigger for mental health? Do you know how to stay healthy and avoid this common root cause of depression and other mental health issues?

In this blog you will learn:

  • Which types of infectious pathogens can cause an infection and potentially a mental health issue
  • Which types of mental health problems are possibly due to infection as a root cause
  • How do infections cause mental health issues
  • What can you do to avoid infection or reduce the severity of an infection

In June, we wrote a few blogs about how infections can be a trigger or a root cause of mental health issues. There is plenty of research out there on this topic. We refer you to read our blogs:

  • Read here for how infections can cause mental health problems. 
  • Read here  for info on how this can be treated. 
  • See here how important a trigger brain inflammation can be. 
  • Read here about how to test for these infections that can cause mental health problems. 

We’ll give you a quick re-cap then we want to focus on some ways to prevent or reduce the severity of infections.

Quick Re-Cap

  • Infections are caused by harmful agents that we call pathogens. Pathogens get into the body from the outside. Infections are passed on from other people, insect bites, contaminated food, water or soil.
  • The most common pathogens that cause infection are viruses, bacteria, fungi and parasites. 
  • Common viruses are the common cold or flu, Covid-19, hepatitis or respiratory viruses.
  • Common bacterial diseases are strep throat, salmonella, STIs such as chlamydia or gonorrhea or urinary tract infections.
  • Common diseases caused by fungi are ringworm or athlete’s foot, fungal nail infections or vaginal yeast infection / vaginal candidiasis / thrush.
  • Common parasites that can cause disease are giardia, pinworms or hookworm.
  • Mental health problems can be caused by these infections. Read here to learn more.

Infections can cause a range of psychiatric symptoms such as delirium, psychotic disorder or mood disorder (Müller, 2014). Chronic infections and chronic inflammation can affect mental health and potentially trigger different types of mental health issues (Pape K, 2019). 

Examples of specific infections that can lead to mental health issues:

  • Bacterial infections (for example Lyme disease, Lyme co-infections, strep throat, H pylori, syphilis): If left untreated, these bacterial infections can lead to serious psychiatric problems. 
  • Strep throat can cause PANDAS
  • Psychiatric illnesses caused by Lyme disease include autism spectrum disorders, schizoaffective disorders, bipolar disorder, depression, anxiety disorders (panic, social anxiety, generalized anxiety, PTSD) and eating disorders (Bransfield RC, 2019).
  • Neuroborreliosis is caused by a systemic Borrelia infection, which is the bacteria that causes Lyme disease. Neuroborreliosis is a neurological manifestation of Lyme disease. People diagnosed with neuroborreliosis have poor mental health, compared to that of healthy people (Staszewska, 2021). People diagnosed with neuroborreliosis can have difficulties functioning in social, professional and educational areas of life (Staszewska, 2021). 
  • Helicobacter pylori is a bacterial infection in the gut. It can ultimately lead to ulcer or stomach cancer if not treated. It can be present in a person and not be pathogenic or harmful. In cases of pathogenic H. pylori infection, there is an increased incidence of depression (Mohamed DM, 2023). And in fact, the severity of the H pylori infection is related to the severity of the depression (Mohamed DM, 2023). 
  • Viruses have been associated with schizophrenia, bipolar disorder, depression and other chronic mental illnesses (Hobbs, 2016). This can be from the flu virus, human endogenous retroviruses and the herpes viruses (which are Epstein-Barr virus, herpes simplex 1 / 2 viruses and cytomegalovirus) (Hobbs, 2016).
  • The herpes simplex virus can hide in brain tissue. The virus lays dormant and can get reactivated when the immune system is weak or suppressed. A herpes virus reactivation can cause encephalitis, or inflammation in the brain that is caused by infection (University of Illinois Chicago, 2021). This brain, or neuro, inflammation can lead to brain damage, memory loss or depression (Troubat R, 2021).
  • Epstein-Barr virus (EBV) is a herpes virus that causes mononucleosis, otherwise called mono. As far back as 1989, it was seen that psychiatric patients with depression and manic-depressive illness also had a chronic active infection with the Epstein-Barr virus (Cooke RG, 1989). EBV is associated with increased risk of schizophrenia (Johns Hopkins Medicine, 2019). EBV can induce neuroinflammation, and stimulate the development of encephalitis (Zhang N, 2021), which can cause depression and other mental health problems.
  • With the Covid-19 virus, people may have symptoms related to brain / mental health. These include cognitive and attention deficits (brain fog), anxiety, depression, psychosis, seizures or even suicidal behavior (NIH, 2023). Covid sufferers are more likely to develop mental illnesses in the months following infection, including PTSD (NIH, 2023). 
  • Many people with Candida, a fungal yeast infection, experience mood disorders like depression and anxiety, panic attacks, unusual mood swings and / or irritability. A Candida infection plays a role in affecting the memory. A Candida yeast infection in the digestive tract can affect the gut-brain axis. This can disturb brain processes that are important for memory (Johns Hopkins Medicine, 2016).
  • Parasite infections can be a cause of mental health issues. The infections cause inflammation that affects the brain. Parasite infections are known to cause increased activation of the immune system which in some people can increase the risk of mental illness (Cambridge Univ. Press, 2022). 
  • Infectious diseases can be the onset of anxiety disorders in adults and children (Witthauer C, 2014). In one study, the bacterial infections whooping cough, scarlet fever and diphtheria increased the prevalence of anxiety disorders (Witthauer C, 2014). People with both infectious diseases and anxiety disorders had lower levels of mental quality of life (Witthauer C, 2014). 
  • Chronic anxiety that will not go away can be due to an autoimmune response, triggered by common infections. The infections create autoantibodies that create inflammation in the brain. This could lead to infection-induced autoimmune encephalopathy. If left undiagnosed, or improperly diagnosed, the patient will be left with a lifetime of anxiety and other mental health issues.

Which Mental Health Issues can be Caused by Infection?

For any mental health issues, we should be looking at infection as a potential root cause. The following mental health conditions can frequently be brought on by an infection: 

  • Depression or MDD (major depressive disorder)
  • Anxiety
  • Schizophrenia 
  • Bipolar disorder
  • Autism 
  • Encephalopathy: this is an altered mental state often caused by infection, in one type of encephalopathy.

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Why & How Do Infections Cause Mental Health Issues?

At this point, we can narrow in on three major factors causing mental health issues. Infection can influence all three.

  • Inflammation: It is increasingly clear that inflammation, especially brain or neuro inflammation, is a key component of mental health problems. Infections of all types increase inflammation. The gut brain axis is involved in the link between infection and mental health. Other factors involved are brain or neuroinflammation and the permeability of the Blood Brain Barrier. Viruses, and other infections, can trigger particular immune and signaling pathways. Higher levels of inflammatory cytokines may be the key mechanism between viral infections and schizophrenia, for example. These issues ultimately lead to inflammation and brain disease processes that can result in a mental disorder. 
  • Genes: Genes may play a small role. No particular gene is responsible for mental health issues but it is thought that genes contribute small effects to overall mental health. Changes in how certain genes express themselves can occur due to an infection.
  • Epigenetic factors: Epigenetic factors are diet, lifestyle, environmental and external factors that affect health. Health, in fact, is heavily influenced by epigenetic factors. These factors have a 70-80% influence on your health, meaning that genetic factors are only have maximum 20-30% influence on your health. The many other epigenetic factors involved in mental health include social and environmental influences. These might be childhood abuse, trauma, neglect, social isolation or loneliness, experiencing discrimination such as racism, social inequality, adverse childhood experiences, stigma and deprivation.  Day to day epigenetic environmental factors that we can control (diet, stress, exercise, toxins, sleep) can also heavily contribute to mental health issues.

What Can You Do to Avoid Infections & to Reduce the Severity of an Infection?

The key to avoiding infection is to have a strong immune system. This will mean you don’t catch every little bug going around. And if you are infected by something, a strong immune system will reduce the severity of the infection. You can boost your immune system through epigenetic diet and lifestyle habits.

  • Poor nutrition plays an important role in the development of mental illness. Eat a nutritious diet and avoid processed foods to improve well-being and mood. 
  • Manage stress through meditation, deep breathing, yoga, tai chi, a bubble bath or getting out into nature.
  • Be active, exercise and avoid excessive sitting. Physical activity is good for both mind and body.
  • Avoid excessive intake of toxins like cleaning chemicals, alcohol or toxic mold in the home/ office. 
  • Don’t smoke. 
  • Keep your weight at a healthy level and lose weight if necessary. 
  • Get a good night’s sleep every night. Poor sleep affects mental well-being.
  • Take reasonable steps to avoid infection, such as washing hands, avoiding people with an active infection and cooking meats thoroughly.

Boost immunity by incorporating natural antibiotic, anti-microbial, anti-viral and anti-fungal substances into your diet and life:

  • Oregano/ Oil of Oregano: Oregano is antibacterial (meaning it fights bacteria that can lead to infection), antimicrobial (fights microbes), antiviral (fights viruses), antifungal (fights fungi), anti-inflammatory (fights inflammation) and cancer suppressant. It helps with chronic digestive issues and yeast infections. Oregano is very potent, so you should talk to your Functional Medicine doctor before taking it. Oil of oregano should only be taken for a short period of time. Do not use it for more than 1 month at a time. Start low with dosing. It can be toxic and even lethal if you take too much so just use the recommended amount of oregano to get the benefits. 
  • Raw Apple Cider Vinegar (ACV): Apple cider vinegar is antibiotic and antiseptic. It can help with weight loss, low stomach acid and other digestive issues. ACV can also be used topically to naturally disinfect a wound.
  • Raw Honey: Raw honey is a super food. It is antibiotic, full of antioxidants, antimicrobial, anti-inflammatory and antiseptic. Honey can be used to treat wounds and avoid infections. Honey can soothe digestive problems, reduce hay fever (if local) and strengthen immunity.
  • Turmeric: Turmeric is anti-inflammatory and can protect against infection. When mixed with honey, it can be topically applied to a wound. 
  • Grapefruit Seed Extract (GSE): GSE is effective in killing viruses, bacteria, fungi and parasites. It is a natural insect repellent. It can boost immunity and help with chronic digestion issues.
  • Garlic: Garlic fights germs. The allicin in garlic can protect against yeast, parasites and bacteria.
  • Echinacea: Echinacea is an herb that fights bacteria. Take echinacea when you feel a cold coming on, as it has preventative properties against the common cold.
  • Cruciferous vegetables: Cruciferous vegetables include broccoli, cauliflower, Brussel sprouts, cabbage and others. This group of vegetables contains sulfur, which activates detoxification pathways. They help the body to detoxify whatever it is fighting, such as bacterium, viruses, fungi or parasites. As cancer often involves an excessive toxin load, cruciferous vegetables can help in fighting off cancer. They can also help with weight management, improve digestion issues and prevent chronic disease through improved detoxification. 
  • Extra Virgin Coconut Oil (EVCO): Coconut oil is antifungal and antimicrobial. It can boost the immune system and help to balance blood sugar. As a healthy fat, EVCO also helps with brain function. 
  • Fermented Foods: Unpasteurized sauerkraut, homemade pickles and probiotic yogurts are all fermented and contain live bacteria. They have amazing benefits for the gut microbiome. They also fight bacteria and cancer prone cells.

In addition to epigenetic factors already mentioned (diet, sleep, stress, exercise), there are other important ways to optimize mental health:

  • Talk about your feelings. Sharing and being listened to can help to feel less alone with any problems you might be dealing with.
  • Practice mindfulness. This helps to stay in the present moment, which can reduce stress.
  • Keep in touch with your social circle. Supportive friends or family help us cope with the stresses of life. This support gives you a different perspective from whatever is going on in your head.
  • Likewise, take care of others. Work on your relationships with family and friends, let go of old grudges or get out and volunteer.


  • Infections, such as bacteria, viruses, fungi or parasites, can be the trigger for mental health issues. Or they may just simply be part of the root cause picture of a mental health problem. 
  • These infections can cause various mental health problems including depression, anxiety, schizophrenia, bipolar disorder, autism, encephalopathy, PANS / PANDAS or other mental health conditions
  • It is increasingly clear that inflammation, especially brain or neuroinflammation, is a key component of mental health problems. Infections of all types increase inflammation. 
  • Epigenetic factors can also significantly influence mental health status. Epigenetic factors are environmental and external factors that affect health, such as diet, stress, exercise, toxins, sleep, trauma, social inequality, childhood experiences, stigma and deprivation.  
  • To avoid infection, do your best to optimize your health through these epigenetic factors. Eat a nutritious diet. Sleep well. Exercise. Maintain a healthy weight. Manage stress.
  • There are certain natural antimicrobial foods and supplements you can use such as raw honey, garlic, turmeric and others to boost your immune system strength.
  • You can also look after your mental health by having a strong social support circle, talking things through and practicing mindfulness. 
  • Check in with a Functional Medicine doctor, or our clinic, to address a case of poor mental health in yourself or a loved one.

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Dr. Miles has spoken for the following organizations:

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