Many studies have been done on the effects of estrogen on the human body but the relationship between estrogen and cognitive function has only recently been studied. Estrogen is a hormone made by the female ovaries (and some by the adrenal glands) that has a great many effects on the body, including the central nervous system. Estrogen has been known to affect cognitive function and mood because of its effects on several neurotransmitters in the brain. Neurotransmitters are molecules that travel from one nerve to another, exerting an influence on the nerve that is stimulated.
Estrogen is believed to play a role in the function of the neurotransmitters serotonin, GABA, epinephrine, norepinephrine, and acetylcholine. Cells of the brain have estrogen receptors that are influenced when estrogen links to the various nerves of the brain.
Effects of Estrogen on Cognition
Estrogen is believed to play a role in the differences in cognition between men and women. It may affect the female cognitive status as early as in the prenatal period. There are indications that the woman has different levels of cognition at different times in the menstrual cycle as a result of varying levels of estrogen during the cycle. This includes memory functioning. Estrogen also is believed to be the reason why women have more depressive symptoms when compared to men.
The lack of estrogen after menopause is believed to be the cause of mood changes related to menopause as well as the increase in insomnia, depression, anxiety and cognitive changes. This is thought to be due to the effect of estrogen on the limbic system.
Estrogen in the Brain
Several decades ago, estrogen receptors were identified and mapped on various parts of the brain. It was found that estrogen receptors were specifically found in the pituitary gland, hypothalamus, cerebral cortex, hippocampus (the memory center of the brain), the brainstem, and the midbrain. The actions of estrogen on the brain are widespread, affecting the cholinergic, serotonergic, GABAergic, and catecholaminergic symptoms of the brain. Estrogen is believed to act on many areas of the brain that can affect the woman’s cognitive function.
Estrogen increases the concentration of enzymes found to be crucial in memory function. These enzymes are found to be critically low in women suffering from Alzheimer’s disease. Estrogen may protect brain cells from suffering from early cell death due to its antioxidant effects on the cells.
Cognition refers to the whole of human information processing. It includes the ability to recognize patterns, psychomotor function, learning and memory, problem solving, attention, language, and abstract reasoning.
In mammalian females, including humans and animals, estrogen has been found to have an effect on more than just reproduction. It affects cognitive behaviors, depressive symptoms, and anxiety. In a study on rats out of the journal Neuropsychopharmacology in 2006, it was found that those that had their ovaries removed, experienced depression and anxiety and cognitive function declined.
Estrogen in Memory and Learning
You need estrogen to learn new things and to retain memory. The estrogen receptors on the hippocampus of the brain appear to be associated with the ability to learn new things and to transfer short-term memory to long-term memory. Estrogen not only modulates the formation of memory and the maintenance of long term memory but it also seems to be related to the ability to solve a mental task, altering what information is learned and how that information is retained. The strength of the memory depends on the presence of estrogen within the brain.
Studies on rats in the scientific journal Science in 2000 showed that those rats with high estrogen levels had better abilities to learn when compared to rats that had low estrogen levels. It is believed that estrogen acts as a conductor in the brain, allowing for enhanced learning and memory. Estrogen may influence the brain’s neurotransmitters, including acetylcholine, that regulate excitability and the ability to memorize certain tasks.
The Effect of Estrogen on Cognition and Aging
As estrogen is required for adequate learning and memory, its lack after menopause is believed to be why some women after menopause suffer from some degree of cognitive decline. It has been suggested that estrogen replacement therapy, especially when given soon after or during menopause, may reverse this effect, resulting in an enhancement of memory and learning in some postmenopausal women.