Parasites & mental health

When we think about what causes anxiety, depression, or emotional dysregulation, we usually look at life circumstances, trauma, and brain chemistry. But there's a growing body of research pointing to something most people — and most therapists — overlook: parasitic infections.

How parasites affect the brain

Parasites are organisms that live in or on a host and survive by taking nutrients from that host. They're far more common than most people realize — and they don't just affect the gut. Parasitic infections can trigger systemic inflammation, disrupt neurotransmitter production, and alter the gut-brain axis in ways that directly impact mood, cognition, and emotional regulation.

Toxoplasma gondii — one of the most studied parasites in relation to mental health. Research has linked T. gondii infection to increased risk of depression, anxiety, schizophrenia, and impulsive behavior. This parasite, commonly contracted through undercooked meat or contact with cat feces, can form cysts in the brain and alter dopamine production.

Intestinal parasites — organisms like Giardia, Blastocystis, and various helminths (worms) can cause chronic gut inflammation, which disrupts serotonin production. Since roughly 90% of your body's serotonin is produced in the gut, an intestinal parasite can directly affect your mood, sleep, and sense of well-being.

Symptoms that may have a parasitic component

• Persistent anxiety or panic that doesn't respond well to traditional therapy alone
• Depression that feels physical — heavy, foggy, and hard to explain
• Brain fog, difficulty concentrating, or memory issues
• Chronic fatigue that sleep doesn't resolve
• Digestive issues alongside mood changes
• Irritability, emotional reactivity, or feeling 'not yourself'
• Sleep disturbances, especially waking between 2–4 AM

Why this matters for your healing

If you've been doing the emotional work — therapy, journaling, self-reflection — and still feel stuck, it's worth considering whether something physical is contributing. This isn't about replacing therapy with a medical diagnosis. It's about honoring the reality that your body and mind are one system, and sometimes healing requires addressing both.

In our work together, I hold space for the whole picture. If something feels "off" in a way that therapy alone hasn't resolved, I'll encourage you to explore medical possibilities alongside our therapeutic work. Somatic and nature-based approaches are especially helpful here because they reconnect you with your body's signals — the very signals that chronic infection can muffle or distort.

What you can do

• Talk to a functional medicine doctor or integrative practitioner about comprehensive stool testing
• Consider testing for Toxoplasma gondii if you have unexplained mood or cognitive symptoms
• Support your gut health with whole foods, fiber, and reducing processed sugar
• Combine medical treatment with body-based therapy for a whole-person approach
• Don't dismiss persistent symptoms as 'just stress' — your body may be telling you something important