1. Nationwide Danish Cohort Study (2021)
The strongest population-based evidence comes from a nationwide Danish study involving nearly 7 million people.
Researchers found that individuals diagnosed with hospital-treated Lyme borreliosis had:
- 28% higher rate of any mental disorder (IRR 1.28)
- 42% higher rate of affective disorders (including depression) (IRR 1.42)
- About twice the rate of suicide attempts (IRR 2.01)
- 75% higher rate of death by suicide (IRR 1.75)
The risk appeared greatest during the first six months after diagnosis for psychiatric illness and during the first three years for suicide. Despite these relative increases, the absolute risk remained low, meaning most people with Lyme disease do not attempt or die by suicide.
2. Post-Treatment Lyme Symptoms
Among patients with persistent symptoms after Lyme disease (often called Post-Treatment Lyme Disease Syndrome, PTLDS), one study found:
- Approximately 20% reported suicidal ideation
- Suicidal thoughts were strongly associated with moderate to severe depression
- The authors recommended routine screening for depression and suicidality in these patients.
3. Possible Mechanisms
Researchers have proposed several explanations for increased suicide risk:
- Neuroinflammation
- Central nervous system involvement (Lyme neuroborreliosis)
- Depression and anxiety
- Cognitive impairment ("brain fog")
- Severe chronic pain
- Fatigue and sleep disturbance
- Functional disability and reduced quality of life
- Social isolation