Robert Wilson in his now infamous Feminine Forever, published in 1966, included Bloss of memory as a menopausal symptom. Although his claim was casually proffered without substantiating evidence, memory complaints are indeed common during midlife.
In the Seattle Midlife Health Study, for example, 62% of 230 women responded Byes when asked whether they had noticed memory changes during the past few years.
Similarly, when we asked participants in the Melbourne Women’s Midlife Health Project whether during the preceding week they had particular trouble recalling recent events, 36% of 249 women replied affirmatively. Because midlife is a transitional period of hormonal change, one might easily ascribe memory symptoms to con- current endocrinologic changes. Wilson certainly would have.
Of these changes, most salient is the loss of estradiol, cyclically produced in women of reproductive age by the maturing ovarian follicle.
There are various forms of memory, implicating different brain loci and different neurophysiological processes. The type with perhaps the greatest clinical import is episodic memory.
This form of memory involves exposure to new information during a discrete event, or episode, and then conscious recollection of this information at a later time. The interval between exposure and recall can vary between minutes and days, or even years. In the 1950s, it was discovered that surgical resection of the hippocampus and nearby portions of the temporal lobes led to a profound, permanent inability to acquire new episodic memories.
In striking contrast, previously learned memories were largely spared. It is now appreciated that new memory formation of this type depends critically on integrity of the hippocampus and adjacent structures of the medial temporal lobes of the brain, although the memories themselves or, more precisely, the neural substrates on which these episodic memories depend are not themselves located within the medial temporal lobes. In the laboratory, effects of estradiol on hippocampal function would seem to enhance episodic memory.
Episodic memory deficits are especially characteristic of Alzheimer disease.