Many of you are probably aware of the placebo effect. The placebo effect is when a doctor administers a "fake" medication, such as a sugar pill, to a portion of the test subjects, while giving others the actual medicine being studied. While the sugar pill is meant to stand as a baseline for no change, many patients report improvements in their health after taking it. This is caused by the psychological effect of believing that they are receiving medicine, which may actually make their symptoms seem to disappear or improve.  

The nocebo effect works in exactly the opposite way. The nocebo effect occurs when a patient is given something which is completely benign, such as a sugar pill but believes that it causes them ailments. An example of this is a study conducted in Germany on a group of patients with chronic back pain. Before conducting a stretching exercise, half of the patients were told that the stretches may lead to an increase in pain, while the other half of the patients were told that the stretches would not affect their pain levels. The group which was told that the activity could cause increased pain reported significantly higher levels of pain than those who were told that there would be no effect on pain levels. 

A somewhat comical test is one in which researchers warned a group of patients about "WiFi Syndrome." They strapped headbands on the patients, which they claimed would magnify the WiFi signal and send high-powered signals through their brain. Without saying anything more, they put the patients into a room with these headbands on for 15 minutes. About half of the participants reported feeling an upset stomach, dizziness, inability to concentrate, or other ailments. Two of the test subjects couldn't even make it through the 15 minute experiment as they fell too ill. The headbands placed on the patients did absolutely nothing, they were simply plain headbands. All of the side effects that afflicted the patients were made up in their heads.

The nocebo effect is not just something that goes on in medical tests, it occurs in the general public all of the time. One example would be the alleged "Wind Turbine Syndrome."  Wind farms have been around in the United States and Europe since the 1980s, however claims of health effects did not surface until 2002. A very small percentage of people who live close to wind farms report ill health effects, and the ones who do normally stem from areas where anti-wind farm groups have combed through and warned residents of these "health side-effects."  Just as in the stretches for the patients with chronic back pain, being told that there are negative side effects to living near wind farms has caused a proportionally high claim to symptoms. Like in the imaginary "WiFi Syndrome," residents claim common and generic health effects such as trouble sleeping, headaches, irritation, or increased stress. While none of these health effects have been proven to be caused by wind farms, they are likely caused by the mere thought of having them.  

All of these examples go to show the strong connection between the brain and the physical system. Although not all ailments are caused by mental perception or can be cured by changing your mindset, you may be surprised just what the human mind is capable of devising.