Seasonal Depression: Two Peaks: Winter and Summer: Low DHEA

In 1985, I first suggested depression may result from low dehydroepiandrosterone (DHEA). This has since been supported. I have just recently had the need to explain why infection rates increase in winter and in summer. I also first suggested that HIV infection is due to low DHEA in 1985. Subsequently, I decided that low DHEA should also result in increased infection rates from viruses and other agents so I examined the possibility of low DHEA in winter. I found a direct connection (below). A new report that "Women [are] more susceptible to HPV [human papilloma virus] during summer" points out that this is not due to increased sexual activity but may be due to sunlight (March 30, 2004). (HPV is a sexually transmitted infection.) Dr. William Hrushesky reported this finding at the American Association for Cancer Research meeting in Orlando. I was also able to explain how this occurs as low DHEA (below).

The same mechanism, low DHEA, that results in two peaks of infection rates also may explain two peaks of depression. Now, it is known that testosterone decreases the effectiveness of the immune system while DHEA increases the effectiveness of the immune system. Testosterone in people increases in the autumn and winter. DHEA sulfate is also higher in the autumn and spring. I suggest the reason is that increased testosterone of autumn and winter reduces production of DHEA from DHEA sulfate. This may be the reason that infections, such as influenza, increase in the winter and why depression is higher in the winter.

It is my hypothesis that the pineal hormone, melatonin, interacts with DHEA to control, what I call, the "melatonin – DHEA cycle." Also, in 1985, I suggested this cycle controls sleep so it is involved in circadian rhythms. It is known that DHEA is involved in the control of melatonin production and melatonin is involved in DHEA production. Melatonin production decreases during times of strong sunlight. If melatonin production is reduced by strong sunlight which occurs in the summer, then DHEA will be reduced. If DHEA is reduced, I suggest this will precipitate depression in people vulnerable to depression.

A single mechanism may be involved in all depression: low DHEA. The same mechanism may affect people when DHEA is seasonally low, such as winter and summer.