Research has begun to elucidate the relationship between immune system health and general feelings of well-being. Researchers in Israel examined the psychological well-being of teenage girls vaccinated for the rubella virus, a common cause of illness in kids. This process involves injecting portions of the virus into the body so that the immune system can learn to recognize it and protect the person against it if it is ever encountered out there in the world. Following such vaccinations, the immune system can become acutely active, making people feel ill. Those that became slightly ill also became slightly depressed! In the words of the authors, many of the vaccinated girls “showed a significant rise in several standard measures of depressed mood, as well as an increased incidence of social and attention problems and delinquent behavior… Thus, even a mild viral infection can produce a prolonged increase in depressive symptoms in vulnerable persons.”

The same group of researchers took their investigations into the relationship between immune system health and psychological functioning one step further. They injected small portions of the cell walls from bacteria into subjects, a technique commonly used to evoke an immune response in humans in order to assess immune system health. Even though the injected material caused no physical symptoms “The subjects showed a transient substantial increase in levels of anxiety and depressed mood. In addition, verbal and nonverbal memory functions were substantially impaired.”

Another study of mood in young females after rubella vaccination found similar results (Yirmaya et al., 2000). In the words of the study authors, “compared to control group subjects and to their own baseline, a subgroup of vulnerable individuals (girls from low socioeconomic status) showed a significant virus-induced increase in depressed mood up to 10 weeks after vaccination.”

Similar findings have been observed when subjects are injected with cytokines, molecules released as part of the body's immune response. Researchers at the University of Illinois Champagne-Urbana argue that cytokines cause many of the symptoms of illness by acting directly in the brain. Here's what they had to say in a recent paper (Dantzer and Kelley, 2006).

	Cytokines “act in the brain to induce common symptoms of sickness, such as loss of appetite, sleepiness, withdrawal from normal social activities, fever, aching joints and fatigue…The fact that cytokines act in the brain to induce physiological adaptations that promote survival has led to the hypothesis that inappropriate, prolonged activation of the innate immune system may be involved in a number of pathological disturbances in the brain, ranging from Alzheimer's disease to stroke…Indeed, the newest findings of cytokine actions in the brain offer some of the first clues about the pathophysiology of certain mental health disorders, including depression.”

Interestingly, antidepressants suppress production of some cytokines (Diamond et al., 2006) and have been found to reduce the symptoms of cytokine-induced depression (Yirmaya et al., 2000; Chiung-Wen Tsao et al., 2006).

And so, it appears that activity within the immune system can have a big impact on how otherwise healthy people think and feel. It therefore makes sense that a healthy immune system contributes to psychological health and well-being.

The immune system also seems to play a role in many major psychiatric disorders. Researchers have long speculated that there are links between immune system health and psychiatric conditions. Studies performed decades ago suggest that exposure to certain strains of the flu virus during the third trimester of pregnancy increases the likelihood that offspring will develop schizophrenia.

A new category of pediatric ailments called PANDAS includes sudden onset tick disorders and Obsessive Compulsive Disorder and appears to be caused by an autoimmune reaction. Specifically, immune cells seeking the strep bacteria attack brain cells in an area called the basal ganglia. It is possible that transfer factors could be engineered to help balance the immune system in these individuals, perhaps leading to a diminution of symptom intensity.

With regard to immune system health and psychiatric conditions, Sperner-Unterweger (2005) states the following:

	“Treatment strategies based on immune mechanisms have been investigated in patients with schizophrenia and affective disorders. Furthermore, some antipsychotics and most antidepressants are known to have direct or indirect effects on the immune system. Different immunotherapies have been used in autism, including transfer factor, pentoxifylline, intravenous immunoglobulins and corticosteroids. Immunosuppressive and/or immunomodulating agents are well established methods for treating the neuropsychiatric sequelae of immune or autoimmune disorders, for example AIDS and SLE. Therapeutic approaches in Alzheimer's disease also apply immunological methods such as strategies of active/passive immunisation and NSAIDs. Considering the comprehensive interactive network between mind and body, future research should focus on approaches linking targets of the different involved systems.”

And with regard to the etiology and treatment of autism, Kidd (2002) tells us:

	“Autism and allied autistic spectrum disorders (ASD) present myriad behavioral, clinical, and biochemical abnormalities… Immune therapies (pentoxifyllin, intravenous immunoglobulin, transfer factor, and colostrum) benefit selected cases… Current pharmaceuticals fail to benefit the primary symptoms and can have marked adverse effects. Individualized, in-depth clinical and laboratory assessments and integrative parent-physician-scientist cooperation are the keys to successful ASD management.”

An immune system link would certainly help explain the increasing rates of autism. According to the Autism Society of America (www.autism-society.org), rates of the disorder are growing at roughly 10-17% per year. According to an article in the Sacramento Bee, researchers at UC-Davis estimated in 2003 that California was:

“...adding an average of 11 names a day to its list of severely autistic children qualifying for state-financed services. The average lifetime cost of these educational services is $4 million per child. As a result, the increase in children eligible for services represents an increase in the state's long-term financial responsibility of $44 million a day.”

Who knows what the underlying culprit is, but the potential to make progress in the treatment of the disorder by putting funding into the immune system link seems worth considering.