Spending time with friends and family is experienced as enjoyable by most people. It is not only enjoyable: social connectedness plays an important role in overall health and wellbeing.

New discovery

A new discovery by researchers at an American university demonstrated that the immune system directly affects social behavior. They found in meningeal vessels a direct physical connection between the brain and the lymphatic system. This hitherto unknown fact returns us to fundamental questions about human behavior.

Influence of the immune system

For example: can a weak immune system contribute to the inability to have normal social interactions? The answer may have to be affirmative, with major implications for the way health professionals approach specific patient groups.

It was always thought that the brain and the adaptive immune system operated in near-isolation from each other. Now it appears not only that they work closely together but also that some of our traits may be directly related to our immune response to pathogens.

Outdated knowledge

Until a year ago medical students were taught that the blood-brain barrier protected the brain from the rest of the body. This barrier is composed of special cells that are selectively permeable to nutrients and protect the brain against microbes. This barrier concept requires major qualification after the publication of the new discoveries.

More new discoveries

This observation is already the second fundamental shift in recent thinking about the functioning of the immune system in a short time. Participants in the recent Dutch Wim "The Iceman" Hof study spectacularly showed that the autonomic immune system is susceptible to deliberate triggering by exposure to cold and by a special breathing technique.

The most recent evidence shows that the immune and nervous systems operate as one and the same system given the way they are using the same molecules and signaling pathways. The nervous system is heavily involved in all aspects of inflammation and sends information to immune cells on a constant basis.

Gut-brain axis

We are looking at entirely new ways of thinking about the brain and its interactions with the immune system. This will likely yield many interesting discoveries in the near future. Maybe these breakthroughs will prove to be on a par with that of the now famous gut-brain axis, along which the intestines, via for instance the vagal nerve, interact with the brain.


Evolutionary perspectives may readily provide support for the new discovery, as social interactions are important for survival. The immune system develops as a corollary of these interactions because it is being exposed to pathogens. This, on the other hand, also proves essential for the life cycle of pathogens as they can thus spread between hosts.

Historical perspective

In the early 20th century the behavior of children was thought to arise purely from socialization. Parents were told that an excess of motherly love was a serious threat to health. Children's hospitals, armed with these new insights, were furnished with sterile, covered cribs. Children were cared for with minimal direct contact with nurses. Parental visits were not allowed. In orphanages, close friendships between children were also discouraged. The effects were dramatic; in some cases, 90 percent of the children died within a year. They commonly died from mundane childhood diseases such as measles or scarlet fever. No one realized that the weak immune systems of children was the underlying problem ....