Have you ever heard a person in poor health being told “Well, you’ve got to stay positive, that will help”? This seemingly common idea is currently under significant scientific investigation. Indeed, the debate about the degree to which psychological processes can directly influence physical health has received special attention recently. A special supplement of the Annals of Behavioural Medicine directly addressed this topic in February this year and a recent article in the Lancet explored this issue, cautioning us that the relationship between a positive psychological orientation and cancer survival remains unclear .
How you think about your health can have powerful impacts on how you experience your health. In a recent study with a group of cardiac patients, how people thought about their illness (termed “illness cognitions”) was found to have a direct impact on how people experience health and emotional wellbeing . These illness cognitions also affected health indirectly by influencing the types of behaviours people were engaged in to cope with cardiac problems. This study brings to our attention the relevance of psychology in relation to medical illnesses.
In a recent paper in Nature Neuroscience, two researchers at the Scripps Research Institute in Florida report that obese rats with extended access to what they deemed “palatable food” — bacon, sausage, cheesecake, pound cake, frosting and chocolate — exhibited compulsive like eating behavior, much like rats with extended access to cocaine or heroin . This compulsive eating meant that they continued eating despite negative ramifications, in this case a flash of light signaling an oncoming electric shock administered to their foot. This lack of control over behavior with known negative consequences is a hallmark of both drug addiction and obesity. The investigators found that just like drug addicted rats, these obese rats had fewer striatal (a region of the forebrain) dopamine D2 receptors; this is responsible for the observed dampening of their neural reward responses to the food, which caused them to continue to eat, seeking that elusive high.
Although the root cause(s) of stuttering remain unknown, evidence has accumulated from twin and adoption studies that genetics plays a role. Dennis Drayna, a geneticist at the National Institute on Deafness and other Communication Disorders (NIDCD), undertook a study to identify the genes involved in the disorder with the ultimate goal to elucidate poorly defined neural structures and functions regulating human speech. Results from the study were reported recently in the New England Journal of Medicine .
The study focused on a Pakistani family in whom previous work had determined that stuttering was linked to the long arm of chromosome 12 (chromosome 12q). In addition to the affected and unaffected members of these families, the study also included 123 Pakistani stutterers who were unrelated and 270 stutterers from the United States and England. Children under the age of eight were excluded, as they often recover from stuttering, as were people with neurologic or psychiatric symptoms. The control group (non-stutterers) consisted of 96 Pakistanis and 276 North American whites.
The gene Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) encodes a cytokine, a signaling molecule secreted by immune cells that has an effect on other cells and is involved in inflammation. A recent report in Cell Host and Microbe reveals that in the gut, GM-CSF helps protect against infection by a bacterial pathogen .
GM-CSF has long been known to promote the survival and differentiation of dendritic cells, immune cells that are present in small quantities in tissues that are in contact with the external environment, including the skin and the inner lining of the nose, lungs, stomach and intestines. Dendritic cells are immune modulators that originate in the bone marrow and travel through the blood and lymph to the peripheral tissues in an immature state. Once they arrive, they differentiate and function as professional “antigen presenting cells”: they alert T cells and B cells to the presence of any foreign invaders. The T and B cells then mount an immune response.