Positive Thoughts Enhance Immune Response

Summary: Positive Thinking boosts Vaccine Immune Response

A study published on January 19, 2026 revealed that positive expectations, that boost optimism, anticipation and the brain’s reward system enhance immunity. (1)

Positive Expectations increase immune response to vaccines

Thoughts and Feelings Affect our Physical Well-Being

There is evindence that mental attitude and positive expectations have a beneficial impact on medical treatmens (for instance, the Placebo Effect), but the exact mechanism is not yet fully understood.

The ventral tegmental area or VTA is the heart of the reward system, and it is located in the midbrain, and it houses the mesolimbic network. It controls reward processing, dislikes, addiction, learning, and memory. Nerves in the VTA reward expectation by releasing dopamine (a neurotransmitter that that helps us feel pleasure and improves mood) which act upon the limbic system, where the nucleus accumbens (or Nac) is one of the targets of dopamine.

The mesolimbic system gets its name from the Greek word "meso" (middle), after the midbrain, and the Latin particle "limbic" (border or edge).

The study aimed at upregulating the mesolimbic reward systme (VTA and the Nac) and see if it could improve the subjects' immunity after receiving the hepatitis B vaccine.

This Study

This study explored the link between brain and body, in particular, positive emotions and their physiological outcome. Previous studies involving rodents had shown that acting upon the brain's reward system (known as ventral tegmental area, or VAT), improved immunity.

This double-blind randomized trial involved 85 healthy volunteers. A subset of them received training on neurofeedback (NF) and used different mental strategies (cognitive, perceptual, affective, and meta-cognitive) to increase ("upregulate") the targeted brain regions, for instance, by thinking about something nice, like recalling a trip, visualizing a future reward, or imagining sensory activities. They received feedback on the upregulating effect via a screen and learned how to induce the desired effect on a specific part of the brain.

Those who used the "neurofeedback" or NF training, were split into two groups, one of them learned how to increase the activity of their brains' reward system —the domapinergic mesolimbic pathway—. Another grop used NF to control another part of their brain that was not linked to the reward system, and a third set (the control group) didn't practice any kind of mental control.

All subjects received a hepatitis B vaccine, two and four weeks later, their blood was sampled and their antibodies against hepatitis were measured.

Positive Outcomes

Those who had practiced neurofeedback to upregulate their brains "showed significant increases in reward mesolimbic activation." This makes sense, because learning neural feedback creates positive feelings of accomplishment and activates the VAT reward system (even in the second NF group that wasn't specifically targeting the mesolimbic pathway).

But those who had targeted the VAT system and manged to generate a greater VTA upregulation, showed "larger post-vaccination increases in [immunity]"

The second NF group who had "learned to upregulate their non-mesolimbic network regions [but not the TVA reward system]... did not reveal correlation between non-mesolimbic regulation and [immunity] change."

Since VTA upregulation was linked to mental strategies that involved positive thoughts, and positive expectation, this shows how these positive emotions have an immunity enhancing effect.

Together, these findings suggest that consciously generated positive expectations can engage reward circuitry to influence immune function, a process that may be leveraged for non-invasive immune modulation. Lubianiker, N., Koren, T., Djerasi, M. et al. (2026). (1)

Comments

The authors note that mesolimbic activity centered in the VTA not only generates dopamine, but also other brain chemicals like oxytocine, endorphins, and the body's opioid system to manage pain, mood and reward. These have been previously associated with the placebo effect. These neurochemicals could explain the mechanism behind the effects noted in this study.

The trial suggest that the VTA enhances reward seeking behavior and positive expectations, and at the same time it enhances the body's resilience (in this case, immunity) to be able to cope with the challenges that will appear during the pursuit of these expected rewards.

Future studies employing neuralfeedback could help learn how to boost our immunity to fight cancer and chronic inflammation.

References and Further Reading

(1) Lubianiker, N., Koren, T., Djerasi, M. et al. (2026). Upregulation of reward mesolimbic activity and immune response to vaccination: a randomized controlled trial. Nat Med (2026). https://doi.org/10.1038/s41591-025-04140-5