Meghan's mother was at her wit's end. "I know teenagers are temperamental, but Meghan's moodiness seems extreme. Her irritability is affecting the entire family," she told me, casting a troubled glance at her 15-year-old daughter. When I asked Meghan about her health, the girl's sullen face and curt answers confirmed her mother's words.

First I considered whether Meghan's diet might be contributing to her ill temper. Because glucose is the primary fuel source for the brain, blood sugar imbalances can cause irritability. I recommended that Meghan include protein-eggs, legumes, whey protein shakes-with every meal. Because protein is absorbed into the bloodstream slowly, it stabilizes blood sugar levels. I also suggested that she eat more vegetables and fewer sweets to minimize blood sugar spikes. To provide the basic nutrients needed for a healthful balance of neurotransmitters-brain chemicals that influence mood—I advised that she take multivitamin and fish oil supplements daily.

Exercise would have increased production of neurotransmitters, but Meghan was unwilling. Because her symptoms were constant rather than cyclical, it seemed that the girl's irascibility was not linked to her menstrual cycle or other hormonal influences. I considered the herb St. John's wort, which can ease mild-to-moderate depression by prolonging activity of mood-boosting neurotransmitters-but Meghan had taken it previously without effect, so I opted against it. After a few weeks on the new diet, Meghan's mood improved slightly, yet clearly the problem was not resolved.

New Test

I then learned about a new urine test that measures neurotransmitters, including serotonin, which has an antidepressant and calming well as dopamine and norepinephrine, which increase energy and motivation. No other type of neurotransmitter testing is available, so even though the urine tests were (and still are in the investigational stage, I decided to try them. (Your doctor can get information from Neuroscience Inc., 888-342-7272, www.

Results showed that Meghan had very low levels of serotonin. The cause is unknown but may be genetic. I did not want Meghan to take serotonin-boosting antidepressant drugs because these can cause anxiety, insomnia, nausea and liver damage. Instead, I prescribed the amino acid 5-hydroxytryptophan (5-HTP) which is converted in the brain into serotonin-taken daily in capsule form. This supplement is sold at health food stores, is appropriate for teens and adults, and occasionally causes nausea. It can be taken indefinitely and should not be used with antidepressant or psychiatric drugs.

Two months later, Meghan's mother was astonished at the transformation. She told me, "Meghan is even-tempered and polite once again. She has lots of energy, swims daily and does homework without complaint. The whole family is delighted with the change-and Meghan is, too."

Loneliness May Raise Alzheimer's Risk

In a recent study, it was found that older adults who feel lonely are twice as likely to develop Alzheimer's disease as people who do not.

Self-defense: If loneliness is accompanied by symptoms of depression, consult a psychologist or psychiatrist.

Best: Maintain connections with others to safeguard your mental health.

Is It Depression or Low Testosterone?

In two recent studies that looked at a total of 1 1,050 men with low levels of the hormone testosterone, those who received testosterone replacement therapy for three years, on average, had a 70% improvement in scores on a standard test used to diagnose depression.

Theory: Hypogonadism (low testosterone) can affect mood and result in depression. It can also cause fatigue, joint and muscle aches, and erectile dysfunction, all conditions that can, in turn, lead to depression.

Self-defense: If you're a man who experiences any or all of these symptoms, ask your doctor to assess your symptoms and check your testosterone level via blood tests. If you are diagnosed with hypogonadism, ask if testosterone replacement therapy is appropriate.

Caution: Men with prostate cancer, liver disease or high hematocrit (the volume of red cells in the blood) should not receive testosterone replacement therapy.

Depressed? It Could Be Low Folate Levels

In a recent study people with low levels of the I nutrient folate (folic acid) have as much as a 55% higher risk of depression.

Self-defense: Individuals who have a personal or family history of depression should have their blood tested for folate.

If levels are low: Eat folate-rich foods—breakfast cereals, leafy green vegetables, lentils, dried beans, liver and wheat germ—and take a daily multivitamin with 400 micrograms (mcg) of folic acid.

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