Training the brain with positive thinking could help the immune system

The authors of the study, whose results have been published in Nature Medicine, trained participants to activate the ventral tegmental area (VTA) – a part of the brain related to reward – before receiving a vaccine against Hepatitis B.

Those who learned to maintain greater VTA activity had a greater increase in antibody levels after vaccination, a finding that, according to the authors, shows the possible relationship between the activity of some brain pathways and the immune system.

The authors believe that although larger trials and additional research are needed to confirm that positive thinking and VTA activity could impact immune health, the results could be useful to identify targets associated with the placebo effect in humans in future treatments.

Ventral Tegmental Area

The ventral tegmental area (VTA), which is part of the brain’s reward system, controls motivation and expectations.

Studies in animals have shown that this system can affect immunity but it is not clear if this same relationship occurs in humans.

To analyze it, a team of Israeli and American scientists, led by Nitzan Lubianiker, from Tel Aviv University (Israel), taught 85 healthy participants to train the activity of their mesolimbic reward pathway (which includes the VTA).

In this novel approach, the participant chooses mental strategies, such as remembering a trip, while the activity of the mesolimbic pathway is simultaneously visualized using fMRI.

The participant is then provided with real-time feedback on the effectiveness of the mental strategy, allowing them to adapt the strategies over multiple training sessions to achieve greater mesolimbic activity.

After four training sessions, participants received a hepatitis B vaccine. The authors did immunological evaluations of the blood before and up to four weeks after the injection.

When they analyzed it, they discovered that people who learned to maintain greater VTA activity had a greater increase in the levels of protective antibodies in the blood plasma against the vaccine.

They also observed that to maintain high VTA activity, people used mental strategies that involved positive expectations (a reflection of the placebo effect).

Findings suggest a possible relationship between the activity of specific brain pathways and the immune system which could be useful to identify targets associated with the placebo effect in humans and future treatments, according to the authors.

A little understood relationship

In statements to the SMC platform, the professor of Immunology at the University of Granada (southern Spain), Ignacio J. Molina Pineda, remember the connection between the immune and nervous systems is still “little understood.”

In this sense, Lubianiker’s study provides data aimed at explaining the ‘placebo effect’, that is, the beneficial effect based on expectations that we obtain when receiving an inactive substance.

The team has been able to demonstrate in humans that reward circuits positively modulate the strength of the response to the vaccine against hepatitis B and that increasing the activity of a certain brain area “leads to greater production of antibodies against hepatitis B, establishing a direct connection between the brain and the immune system.”

The professor, who has not participated in the study, remembers that just like the placebo effect, “the nocebo effect is recently gaining relevance, which is exactly the opposite,” as illustrated in the vaccination trials against covid, “in which many volunteers who received an inert substance reported side effects similar to those derived from the vaccine.”