A peer-reviewed paper in the American Journal of Psychiatry described Lyme disease as a "neuropsychiatric illness" and documented its association with a wide spectrum of psychiatric conditions — including depression, anxiety, panic disorder, obsessive-compulsive disorder, and bipolar-type presentations. The research is not new. The clinical awareness, however, remains far behind it.
The result is that thousands of patients with neuropsychiatric Lyme disease receive psychiatric diagnoses and psychiatric treatments without anyone investigating whether an underlying infection is driving the symptoms. Psychiatric medications may reduce symptom intensity, but they do not address the biological cause — and many patients remain unwell, or worsen, until the infection is identified and treated.
How Lyme disease affects the brain
Lyme disease does not simply stay in the joints or the bloodstream. Borrelia burgdorferi crosses the blood-brain barrier and directly invades central nervous system tissue. But even without direct invasion, the brain is profoundly affected by what happens in the rest of the body during chronic infection. There are three primary mechanisms:
Borrelia can cross the blood-brain barrier and infect the central nervous system directly — a condition called neuroborreliosis. In late-stage disease, the spirochetes can proliferate in brain tissue, causing encephalitis (brain inflammation), meningitis, and progressive neuropsychiatric symptoms. Advanced MRI brain imaging research at Johns Hopkins has demonstrated measurable structural and functional brain changes in Lyme disease patients — objective evidence that the brain disturbance is biological, not psychological.
Even when Borrelia has not directly invaded brain tissue, the systemic inflammatory response to infection circulates inflammatory cytokines throughout the body. These molecules cross the blood-brain barrier and alter neurotransmitter production and signalling — specifically reducing the availability of serotonin, dopamine, and GABA, the neurotransmitters most directly involved in mood, anxiety, and cognitive function. This produces a biochemical state in the brain that is functionally indistinguishable from depression or anxiety — because at the neurochemical level, it is the same state.
Approximately 90% of the body's serotonin is produced in the gut, not in the brain. When Lyme disease disrupts the gut microbiome — as it consistently does through both direct infection and antibiotic treatment — this serotonin production is impaired. Simultaneously, a leaky gut allows inflammatory molecules (particularly lipopolysaccharides from gut bacteria) into the bloodstream, where they trigger further brain inflammation. The cognitive and mood symptoms that result from this pathway are not "in the mind" — they originate in the gut, travel through the immune system, and arrive in the brain.
Tick-borne infections generate significant oxidative stress throughout the body. The mitochondria in brain cells — which are particularly energy-dependent and sensitive to oxidative damage — are impaired. The result is that the brain cannot generate adequate cellular energy for normal function. This manifests as cognitive fatigue, slowed processing, and difficulty sustaining mental effort — the defining features of Lyme-related brain fog.
Cognitive and psychiatric symptoms in tick-borne illness
Common symptoms in this cluster
- Anxiety that appears suddenly, worsens without clear trigger, or does not respond to usual coping
- Depression, emotional flatness, or persistent low mood that feels different from previous depressive episodes
- Panic attacks without prior history of panic disorder
- Mood instability — rapid cycling between emotional states, disproportionate emotional reactivity
- Irritability or anger that feels out of proportion to circumstances
- Intrusive or obsessive thoughts — particularly during symptom flares
- Brain fog — difficulty thinking clearly, finding words, following a conversation, or making decisions
- Short-term memory gaps — forgetting conversations, losing words mid-sentence, missing familiar information
- Slowed processing speed — thoughts feel "thick" or delayed
- Cognitive fatigue — mental effort becomes deeply and rapidly exhausting
- Depersonalisation or derealisation — feeling detached from the body or from surroundings
- Hypersensitivity to sensory input — sound, light, or crowds become overwhelming
- Sleep disruption — difficulty entering or maintaining deep sleep, unrefreshing rest
- Symptoms that fluctuate alongside physical symptoms — better and worse in parallel
Anxiety and panic in Lyme disease
Anxiety in Lyme disease typically has features that distinguish it from primary anxiety disorder — though the distinction is rarely made in clinical settings because few clinicians look for it. It tends to arrive or intensify during symptom flares, improve somewhat during periods of relative calm, and not respond fully to standard anxiety treatments or psychotherapy alone.
The biological basis is direct: elevated inflammatory cytokines reduce GABA (the brain's primary inhibitory neurotransmitter), increase glutamate activity (the brain's primary excitatory neurotransmitter), and activate the HPA axis — the stress-response system that generates cortisol and adrenaline. The nervous system is pushed into a state of chronic hyperactivation. This produces a physiological anxiety state that is driven by brain chemistry, not by psychological vulnerability.
Among the tick-borne co-infections, Bartonella is particularly associated with anxiety, agitation, and a specific pattern of emotional intensity. Clinicians experienced in Lyme disease have noted that Bartonella-infected patients often present with a level of neurological hyperreactivity — including rage responses, hypervigilance, and panic — that is disproportionate to their other symptoms. Treating Bartonella requires different antibiotics than Lyme itself; failing to identify and treat it means the anxiety component of the illness is left without its primary driver being addressed.
Anxiety is easily attributed to the psychological stress of being ill and undiagnosed — which is real and significant, and does compound the anxiety. But it is not the only cause. Telling a patient that their anxiety is a natural response to their situation, when it is partly or substantially caused by direct neurological inflammation, means that the biological component goes untreated. Both causes can be true simultaneously — but the biological cause requires different intervention.
Depression and mood instability
Depression in Lyme disease is documented extensively in the research literature. Studies across patient populations have found depressive symptom rates of 26–66% in late-stage Lyme disease — far above population baseline. A study referenced in Project Lyme research found that post-infection depression was found in 98% of cases compared to 0% pre-infection in the same patients — a striking signal of infectious causation.
Johns Hopkins Lyme Disease Research Center has clarified an important distinction: while depression and anxiety may develop after chronic Lyme has been established, their research indicates these symptoms are typically consequences of the chronic illness rather than its initial cause. This is clinically significant — it means that treating the depression without treating the infection addresses the symptom while leaving the cause untouched.
Patients with tick-borne illness sometimes present with rapid-cycling mood instability that resembles bipolar disorder. Research suggests that around 10–28% of Lyme patients exhibit bipolar-type presentations. A characteristic feature is the rapid cycling — fast transitions between states, rather than the extended episodes typical of primary bipolar disorder. When this pattern appears without a prior psychiatric history and in the context of physical symptoms spanning multiple systems, tick-borne illness should be considered.
One of the clearest signals that mood symptoms have a biological rather than purely psychological driver is when they fluctuate in parallel with physical symptoms. If depression deepens during a herxheimer reaction and lifts somewhat as a herx resolves, or if anxiety is consistently worst during the same periods as joint pain and fatigue, the shared driver is likely the underlying infection. Mood and body are on the same cycle — because they are driven by the same process.
Brain fog and cognitive difficulty
Brain fog is the term patients most commonly use to describe the cognitive experience of Lyme disease — and it is an accurate description of something quite specific. It is not simply feeling tired or stressed. It is a distinct state in which mental clarity is physically reduced: thoughts feel slow, thick, or inaccessible; words disappear mid-sentence; familiar information cannot be retrieved; reading the same paragraph repeatedly yields no comprehension.
Johns Hopkins research has used advanced MRI brain imaging to demonstrate objective, measurable structural and functional brain changes in Lyme patients experiencing brain fog. This is not a subjective complaint — it is a biologically verifiable alteration in how the brain is functioning. The research team states clearly that Lyme disease-associated brain fog is a real, biologically based condition.
Impairments in verbal fluency, attention, working memory, and processing speed are the most consistently documented cognitive deficits in Lyme disease. These affect daily functioning in ways that may be difficult to convey to others — because from the outside, a person with Lyme brain fog may not appear impaired. The invisibility of cognitive symptoms is part of what makes them so isolating.
It is important to distinguish between two things that are often conflated. Cognitive fatigue means that mental effort depletes very quickly and recovery takes much longer than expected — a task that should take 20 minutes becomes impossible after 10, and the person may need hours to recover. Cognitive impairment means that specific cognitive functions are reduced even at rest — word finding, memory retrieval, processing speed. Many Lyme patients experience both simultaneously. This matters for pacing: pushing through cognitive fatigue in the same way one might push through physical fatigue in a healthy person can cause a post-exertional crash.
The fluctuation signal — what makes this different
The single most important feature that distinguishes neuropsychiatric Lyme from primary psychiatric diagnosis is fluctuation that mirrors physical symptoms. Symptoms worsen together and improve together. This is not a coincidence — it is the same immune and inflammatory process expressing itself across multiple body systems simultaneously.
If anxiety spikes during the same days that joint pain is worst and fatigue is deepest — and then all three improve together — they are almost certainly sharing a common driver. A psychiatrist looking only at mood will not see this pattern. A clinician trained in tick-borne illness will ask about it specifically.
Other fluctuation patterns worth tracking:
Lyme disease — like syphilis, its closest clinical analogue — tends to produce a relapsing-remitting pattern. Periods of relative calm are followed by flares. These flares often affect all systems simultaneously: physical, cognitive, and emotional. When the pattern is consistent over months, it is itself a diagnostic signal.
When bacteria die during antibiotic treatment, they release endotoxins that can temporarily intensify all symptoms — including psychiatric ones. A patient who was managing their anxiety adequately may find it becoming overwhelming in the first weeks of treatment. If this coincides with other herx symptoms (increased pain, fatigue, sweating) and then gradually resolves, it is a herxheimer reaction, not a worsening of the underlying illness.
Primary psychiatric disorders typically have a psychological context for their onset — a period of significant stress, a history of trauma, a family pattern, or a gradual build over years. Neuropsychiatric Lyme often has no such context: anxiety, OCD-type symptoms, or depression can appear acutely, apparently from nowhere, with no psychological explanation. When this is the case and it coincides with a period of potential tick exposure or the onset of physical symptoms, the infectious differential should be explored.
What gets missed — and why
Psychiatric training does not typically include infectious disease as a differential for mood or cognitive symptoms. A psychiatrist who encounters a patient presenting with anxiety, depression, and brain fog will look for psychological causes, family history, and neurotransmitter-based explanations — not for Borrelia burgdorferi. This is not negligence; it is the consequence of a training structure that does not connect these disciplines.
When a patient presents with both physical and psychiatric symptoms and standard testing finds nothing structural, the common explanation is that the physical symptoms are caused by the psychiatric ones — that the body is expressing psychological distress somatically. This reverses the actual causation in many Lyme cases. The psychiatric symptoms are being caused by the biological process, not the other way around. Treating only the psychiatric layer leaves the infection entirely unaddressed.
Standard Lyme testing is insensitive — it misses a significant proportion of actual cases. A negative ELISA does not exclude Lyme disease. When a patient with a complex multi-system presentation (physical and psychiatric) receives a negative Lyme test and is told they do not have Lyme, this represents the test's limitation, not a definitive clinical conclusion. Negative does not mean ruled out.
A physician experienced in tick-borne illness will take a full system history — not just of psychiatric symptoms but of the entire body over time. They will look for the cluster pattern, the fluctuation pattern, the timeline of onset, and any exposure history. They may use more sensitive testing (western blot, specialty laboratory panels) rather than relying solely on a standard ELISA. The goal is a clinical picture, not just a test result.
The research — a brief overview
Neuropsychiatric Lyme disease is not a fringe concept. There are over 400 peer-reviewed articles documenting the association between Lyme disease, co-infections, and neuropsychiatric symptoms. Key findings across the literature include:
Published research has documented associations between Lyme disease and depression, anxiety, panic disorder, obsessive-compulsive disorder, bipolar-type presentations, psychosis, and in severe late-stage cases, dementia-like cognitive decline. A 1994 paper in the American Journal of Psychiatry — one of the earliest and most cited — described Lyme as a neuropsychiatric illness and recommended that psychiatrists in endemic areas include it in the differential for any atypical psychiatric presentation.
Johns Hopkins Lyme Disease Research Center has used advanced MRI techniques to demonstrate objective structural and functional brain changes in Lyme patients. These changes are measurable, reproducible, and not present in healthy controls. The research is ongoing and represents one of the clearest examples of Lyme disease affecting the central nervous system in ways that produce neuropsychiatric symptoms.
A 2024 systematic review (PMC) notes that while the association between Lyme and neuropsychiatric symptoms is documented, the strength and consistency of the evidence varies across conditions. Some associations are well-established (depression, anxiety, cognitive dysfunction in late-stage disease); others are supported primarily by case reports and clinical observation rather than large controlled studies. This uncertainty is an argument for more research — not for dismissing the documented associations that do exist.
Approaching this with a clinician
Raising neuropsychiatric Lyme with a doctor requires preparation. Most clinicians are not aware of the full scope of published research in this area, and many will have a default assumption that psychiatric symptoms are psychiatric in origin. The following approach is practical and evidence-based.
Write down when each symptom appeared, across all body systems. Include joint pain, fatigue, sleep disruption, digestive symptoms, and neurological features alongside the mood and cognitive symptoms. A pattern of multi-system involvement beginning around the same time is much more informative than a list of psychiatric symptoms alone.
Note days when psychiatric symptoms are better and worse. Note whether they correlate with physical symptoms. If you can show a clinician a clear pattern of joint pain, fatigue, and anxiety rising and falling together, you are showing them a systemic pattern — not a psychiatric one.
Do not wait to see if the clinician raises it. Ask directly: "I have read that Lyme disease can cause neuropsychiatric symptoms. Given my history, would you consider it worth testing for?" A clinician familiar with the evidence will engage with this seriously. One who dismisses it entirely may not be the right specialist for this particular question.
Having neuropsychiatric Lyme does not mean that psychological support, therapy, or psychiatric medication are irrelevant. Managing the biological component — the infection and inflammation — is primary. But psychological support, pacing, and appropriate medication can meaningfully reduce symptom burden while treatment addresses the underlying cause. One does not exclude the other.
These symptoms are not a character failing
Anxiety, depression, and cognitive difficulty in the context of chronic illness are extraordinarily isolating — partly because of the symptoms themselves, and partly because of how often they are attributed to weakness, hypochondria, or psychological fragility. They are none of these things. They are the brain responding, in predictable biological ways, to an inflammatory burden that has been placed upon it by infection.
Understanding the mechanism does not make the experience easier in the moment. But it does make it possible to approach it with a different relationship — not as something you are causing or prolonging, but as something that is happening to you, with identifiable causes and meaningful paths toward improvement.
Read about healing mindset →Sources & further reading
- Fallon BA, Nields JA — Lyme disease: a neuropsychiatric illness, American Journal of Psychiatry, 1994
- Jonczak E et al. — Neuropsychiatric Manifestations of Lyme Disease: A Literature Review, PMC, 2024
- Merchant S et al. — Neuropsychiatric Manifestations and Cognitive Decline in Long-Standing Lyme Disease, PMC, 2024
- Johns Hopkins Lyme Disease Research Center — Research Substantiates Lyme Disease is Not a Psychosomatic Illness
- Dr. Todd Maderis — Lyme Disease and Depression (drtoddmaderis.com)
- Project Lyme — The Impact of Lyme Disease on Mental Health (projectlyme.org)
- Daniel Cameron MD — What Does Lyme Disease Do to Your Brain? (danielcameronmd.com)
- Horowitz R. — Why Can't I Get Better? (2013)
Last updated: March 2026