It reduces the negative symptoms of ADD for some people, but not for others.

NPR: Excerpt: 'Delivered from Distraction'

As the brain matures, it changes in ways that may cause the negative symptoms to abate.

NPR: Excerpt: 'Delivered from Distraction'

But the MoD says it is too early to say that the combination of vaccines and anti-nerve tablets necessarily caused negative symptoms, or was responsible for the so-called Gulf War syndrome.

BBC: The Gulf War syndrome: fact or fantasy?

The experts also propose a third category for "gluten sensitivity, " in which patients report the same symptoms as celiac disease but test negative for telltale antibodies.

WSJ: New Guide to Who Really Shouldn't Eat Gluten

Some women may be wary of taking an antidepressant for menopausal symptoms, and cost also may be a negative factor, the physician noted.

CNN: Health - Anti-depressant counters hot flashes from menopause, chemotherapy

Symptoms may also be more severe, with repeated negative thoughts about the baby, about oneself as a mother, or of causing harm to the infant.

FORBES: Postpartum Psychology: Depression, Anxiety, OCD, and Psychosis

So when the family of an elderly woman insisted that she be admitted to the hospital after stroke-like symptoms, he agreed to do so, even though her test results were negative and he wanted to send her home.

FORBES: Why Rating Your Doctor Is Bad For Your Health

In London, a hospital spokesman said a British Airways crew member developed flu-like symptoms during a flight from Mexico City and was tested for swine flu, but the results came back negative.

CNN: U.S. prepares for possible swine flu epidemic as global cases rise