BOSTON -- In Thursday's medical news, NewsCenter 5's Liz Brunner reported on whether scientists say junk food is addictive, how chocolate can boost your brainpower and a connection between post-traumatic stress disorder and physical illnesses in soldiers.

Post-Traumatic Stress

Post-traumatic stress disorder is leading to more physical health problems for U.S. soldiers, according to the American Psychiatric Association.

Researchers studied nearly 3,000 active duty troops who rotated back into the U.S. after serving in Iraq.

They found 46 percent of those diagnosed with post-traumatic stress disorder reported their health as fair or poor and had missed more days of work than those without the stress disorder.

Doctors said the study suggested that veterans with health problems may be suffering from undiagnosed post-traumatic stress disorder.

Chocolate And Brainpower

It's already been proven to help lower your blood pressure, and now research shows chocolate may also be good for your brain.

Researchers at Wheeling Jesuit University found that volunteers scored better on verbal and visual memory tests after eating 85 grams, or about two bars, of milk chocolate.

Reaction times also improved after subjects ate both dark and milk chocolate.

Researchers said they believe stimulants in the chocolate, including caffeine, improve blood flow to the brain.

Addictive Junk Food?

Chocolate and other sugary sweets could be addictive, according to new research.

Scientists said it's not the sugar, but the high it produces.

Researchers at Princeton University found when they fed rats a sugary meal, the rats experienced a flood of dopamine -- the "feel-good" chemical in the body.

Within a few days, the rats wanted more sweets with each meal. And when the sugar was removed, they showed anxiety.

Researchers said the addiction is milder than a drug addiction and it's too early to know how the study may apply to humans.