How do these hormones influence brain function?
This hormone has a very powerful influence on brain and the imbalances are evident during menopause. It is hands down the most studied hormone in the literature. The main reason is due to menopause. Since estrogen levels decrease in menopause we see neurological changes like loss of cognitive function, mood changes, decrease in motor skills, depression, etc. So we can see that estrogen expands far beyond just reproductive behavior. It has been connected to cognitive properties as verbal and spatial memory, fine motor skills and depressive illness. There is a connection with serotonin receptors and estrogen levels. The correct balance of estrogen has been shown in increase serotonin receptors in the prefrontal lobe which helps with cognition and mood.
This hormone also has a affect on the brain. It has been shown to excite GABA receptors in the brain which induces a calming effect. There are possibilities that it promotes myelination of the CNS. It appears that it has neuroprotective properties on neurons. Progesterone is known for its anti-inflammatory effect and has demonstrated good outcomes for acute stages of traumatic brain injury.
Testosterone is extremely important for healthy aging in males and just as important for neuronal health. The decline of testosterone in males in conjunction with cognition and brain aging is well established in the literature. Testosterone has shown neuroprotection in studies. Testosterone is also heart protective in males and not heart protective in females. When testosterone levels increase in females it leads to infertility and difficulty in weight loss.
What is important is that these hormones are in balance. For example here is what can happen when they are out of balance (whether metabolically or by hormone replacement therapy).
Progesterone that is out of balance has been shown to increase the risk for breast cancer. In males if a certain enzyme is not working correctly and his lab test show low testosterone, giving him more testosterone can cause his body to convert it into estrogen. Out of balanced estradiol can cause an increase in thyroid binding globulin which will cause a decrease in thyroid tissue expression.