Estrogen Loss Increases Alzheimer’s Disease Risk In Women

Several studies have suggested that estrogen loss in women may contribute to Alzheimer’s disease and other dementias.

One such study involved over 8,800 female residents of a retirement community situated in Laguna Hills, southern California. The residents were surveyed on various health related questions in 1981. Over the 11 year study period, 138 of the participants were diagnosed with Alzheimer’s disease or other dementias likely to be Alzheimer’s disease.

The study found a significant reduction in the likelihood of developing Alzheimer’s disease amongst those using estrogen replacement therapy compared to those not using the therapy with the odds of estrogen users developing Alzheimer’s disease 32 percent lower than those not using the therapy.

The study also found the risk of developing Alzheimer’s disease decreased significantly when the estrogen dose was higher and when the duration was longer. The study also found that the risk of Alzheimer’s was higher the later each women experienced their first menstrual period.

The researchers concluded that: “This study suggests that the increased incidence of Alzheimer’s disease in older women may be due to estrogen deficiency and that estrogen replacement therapy may be useful for preventing or delaying the onset of this dementia.”

Another study, which formed part of the Baltimore Longitudinal Study of Aging (BLSA),  found that women using hormone replacement therapy (HRT) were 50 percent less likely to develop Alzheimer’s disease during the sixteen year study period.

Estrogen raises levels of several neurotransmitters such as acetylcholine, serotonin, noradrenaline and dopamine. Low levels of acetylcholine are often found in individuals diagnosed with Alzheimer’s disease and it is thought that the ability of estrogen to increase acetylcholine levels in the brain may be responsible for the relationship between estrogen levels and Alzheimer’s disease.

Estrogen has also been shown to reduce or prevent the formation of beta amyloid plaques which are found in the brains of Alzheimer’s sufferers. Estrogen can also improve blood flow in the brain and raises the levels of nerve growth factors in the brain.

Endogenous estrogen levels are largely determined by genetics however hormone replacement after menopause can help women maintain higher estrogen levels in later life.