Q. What causes low serotonin in the brain? What are the symptoms? Are there any treatments available? Does it make a person moody, depressed and withdrawn?

A. We don't know how many individuals actually have low serotonin levels in the brain, or precisely why they do, but we have a lot of indirect evidence that abnormal serotonin (5HT) function has a great deal to do with depression and anxiety.

Common symptoms of depression include low energy, feelings of hopelessness, poor sleep and appetite, severe guilt feelings, and loss of interest or pleasure in most aspects of life. There is some evidence from animal studies that one's genetic make-up may influence 5HT function in the brain (a technical review is found in Arango et al, J Psychiatr Res. 2003 Sep-Oct;37(5):375-86). However, other studies in animals suggest that early social exposure or isolation may also influence brain 5HT function (Lapiz et al, 2001).

In some cases, nutritional factors may influence brain chemistry. For example, people deficient in folic acid (which is involved in 5HT production) may become depressed. And--since both antidepressants and psychotherapy may produce similar changes in the brain--there's even reason to think that simply talking to the right person may change our brain chemistry for the better (Liggan & Kay, J Psychother Pract Res 8:103-114, April 1999).

For more details on how brain chemistry is related to mood states, and how depression may be treated, I recommend Dr. John Medina's book, "Depression: How it happens, How its Healed" (New Harbinger Publications1998) and "Living Longer Depression Free", by Mark D. Miller and Charles F. Reynolds (Johns Hopkins University Press, 2002).

December 2003

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