Brain enemies +

(the most deadly five "enemies" of the brain: depression, Parkinson's, Alzheimer's, stroke, and autism)

1. depression
Depression seems to be a function of stunted cell growth.

It happens when brain cells fail to forge new connections with one another. The wide range of symptoms suggests that many areas play a role.

Some studies have shown that shrunken neurons in the hippocampus, an area that consolidates memories, could explain the cognitive deficits of depression.

Depression is the leading cause of disability worldwide. Exact numbers are impossible to determine, but it is said that there 30,000 suicides each year in the United States; one every 17 minutes.

One therapy called "deep-brain stimulation", uses electrodes that jump-start chemical communication between brain cells.

2. Parkinson's
For reasons scientists still don't understand, cells that produce a brain chemical called dopamine begin to die in a region of tissue that facilitates muscle movements.

When dopamine levels drop, neurons start to fire abnormally, causing the classic Parkinson's tremors.

One percent of the U.S. population over 60 has Parkinson's disease. Only stroke and Alzheimer's cause more deaths as a result of brain dysfunction. The disease is still incurable.

3. Alzheimer's
Bungled genetic instructions can cause proteins to tangle and to build up inside or in between nerve cells.

The result is that neurons die, leading to memory loss, dementia, and eventually death.

Certain genes increase the odds of Alzheimer's, but the most critical known risk factor is simply old age.

About 4.5 million Americans have the disease. That number is expected to triple to more than 13.2 million by 2050, when 20 percent of the U.S. population will be over 65.

Alzheimer's is the seventh leading cause of death in the United States.

4. stroke
A stroke is a heart attack in a person's head; an interruption of blood caused either by a clot or a rupture in one of the millions of blood vessels that feed the brain.

Either way, brain cells die, resulting in any number of symptoms, from partial paralysis to loss of speech or vision, depending on the location of the damage.

An estimated 700,000 Americans suffer from stroke annually, and 150,000 die, making it the third leading cause of death in the United States, behind heart failure and cancer.

Strokes are a major cause of physical disability and dementia.

5. autism
Some parts of the brain, like the frontal lobe and the amygdala, may develop too fast in early childhood, possibly because cells become overwrapped in an insulating layer that may facilitate growth, says neuroscientists David Amaral of the M.I.N.D. Institute at the University of California at Davis.

Exactly how these changes cause symptoms; social impairment, repetitive behaviors, poor language skills, is uncertain, although the frontal lobe is known to regulate behavior and the amygdala, anxiety.

Researchers believe that autism has both genetic and environmental causes.

Autism afflicts one in 150 kids by age eight. Diagnoses are on the rise, although whether because of better recognition or a growing frequency is unclear.

—Excerpts compiled from
"The Deadly Five" by Eric Hagerman in Popular Science;
October, 2007; pages 47-49.

See more topics of interest at this INDEX of Words at Work in the Media.