Depression is one of the leading causes due to death by suicide. The mental illness is still a controversial topic due to the fact it is still being researched in hopes of finding why it occurs and how it can be cured. Many scientists are now devoting millions of dollars into the effort in order to reduce the amount of lives lost to suicide. Among this research, scientists have now found that abuse during childhood could later on lead to adult depression. Scientist now know that abuse at a early age can alter the chemicals and make up of the brain and later cause depression. The abuse sensitizes the stress response in the brain so that those who are abused become overly responsive to environmental pressures. Eventually, even small degrees of stress cause an huge output of stress hormones, and these hormones in turn act directly on multiple sites to produce the behavioral symptoms of depression (the vegetative state, the sleep disturbances, the cognitive dullness, the loss of pleasure).  In the United States alone depression affects 18 million adults ( 1 in 10) in any given year and causes 490 million disability days from work each year in the U.S. With the number of child abuse cases on the rise, it is almost inevitable that depression will be much more common in the future.