If the rate of obesity and overweight continues
to rise, 75 percent of adults and nearly 24 percent of US children and
adolescents will be overweight or obese, recent studies suggest. Obesity is an
increasingly alarming problem worldwide that rivals smoking as a cause of illness
and premature birth, but efforts are done in order to better understand the factors
that contribute to this health condition.
Following this line, a new study examines
the pathways that contribute to obesity. The National Institutes of Health
Study, that appears in the August 28 New England Journal of Medicine, shows
that a brain chemical, known as BDNF (brain derived neurotrophic factor), plays
a role in regulating the quantity of food that people eat and their chances of
becoming obese.
The NIH study involved 33 children and
adults with WAGR syndrome, which is a rare genetic condition in which individuals
lack some groups of genes. The symptoms of WAGR syndrome include Wilms tumor, a
tumor of the kidney, aniridia, genitourinary anomalies, and mental retardation.
Obesity was observed in a subgroup of WAGR syndrome patients. The genetic aberration
occurs in one out of every 500,000 to 1 million persons. Half of the group
studied lacked one or two genes for the brain chemical called BDNF.
The scientists studied the relationship
between genotype and body-mass index (BMI) and found that every person of the
first group was obese by age 10 and reported high levels of overeating compared
to the general population. The 14 other patients who had two working copies of
the BDNF gene were no more likely to develop childhood onset obesity than the
general population. They were less tempted to overeat.
“We suspect that BDNF has important issues
in many parts of the brain, including memory and ability to sense pain,” said the
study’s first author, Jack Yanovski, head of the Unit on Growth and Obesity at
NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human
Development. He said that a larger segment of the population may have the same
problem. The fact that some people can’t control their eating habits or lose
weight may be attributed to gene deletions.
To conclude, the findings add another factor
on the list of factors that predispose children and adults to obesity. The
senior author of the study, Jack A. Yanovski, M.D., Ph.D., of NICHD’s Unit on
Growth and Obesity, said that the brain chemical is believed to work in a combination
with other substances, including the hormone leptin, that regulate appetite and body weight. It
appears that leptine indirectly triggers the release of BDNF in the hypothalamus,
the part of the brain which plays a role in controlling eating.
Researchers said that BDNF is “just a small
part of the puzzle” and more research needs to be done in order to develop new
drugs to treat obesity in people who don’t make enough BDNF.
Obesity is one of the main health problems
is the world, with 400 million obese people classified by the World Health Organisation
around the world. Obesity is also a significant risk factor for a number of chronic
diseases such as heart disease and type 2 dyabetes.
