Do you often curl up alone in your room with a bag of potato chips or a gallon of ice cream? After reading this, you may want to think again. According to researchers at Georgetown’s Lombardi Comprehensive Cancer Center, stress from social isolation and a high-fat diet increase levels of a brain neurotransmitter that promotes obesity, insulin resistance and breast cancer risk. The findings of the study, were reported at the 2011 American Association for Cancer Research(AACR) Annual Meeting. The study compared 4 groups of mice:
- a group that lived together (not socially isolated) and ate a normal diet;
- a group that was isolated (each alone in a cage) and ate normally;
- an isolated group that ate a high-fat diet;
- a group that lived together and ate a high-fat diet.
Results showed that the mice that were isolated and given a high-fat diet developed a major increase in the level of the neurotransmitter NPY. At the end of 17 weeks 92% of the mice in this group had developed cancers. Mice that were isolated for two weeks but fed a control diet also had elevated neurotransmitter levels but, the tumors that developed in the high-fat, socially isolated mice appeared earlier and were larger than in the other groups. The researchers say their findings appear to link to a number of findings in humans, such as the fact that social isolation is associated with an increased risk of cancer development and mortality, and that obesity is a risk factor for breast cancer. Although they suspect that NPY may play a role in development of human breast cancer, there is currently no evidence for such a connection because human studies have not yet been done. “We have yet to translate these findings to humans, but it does suggest that social isolation is a potent stressor and initiates a robust central nervous system response,” says Allison Sumis, a Ph.D. student in GUMC’s tumor biology program.