Effects of Oestrogen Changes

Effects of Oestrogen ChangesExecutive function is influenced by estrogen- in the brain the atomic number 18a associated to executive functions, repositing and attention is the prefrontal cortex (Pettit, 2013). As during the female lifespan the levels of estrogen changes, and the executive functions bugger offs some issues when these levels are low, for example after childbirth and around change of life (Craig et al., 2008). Although the low levels of oestrogen after childbirth and lactation are temporary, after the change of life these levels do not increase by nature.As the world population experience longer life span, some unsoundnesss are estimated to increase with age. One of the most common type of dementia is Alzheimers disease, which mostly occur in subsequent life (Lephart Hedges, 2003). Alzheimers disease come acrosss the working remembering board, attention planning and other executive functions it is a progressive disease and it is considered by deteriorating c ognitive deficits, affective disturbances, delusion, and on the later stages, it also incision motor and sensory line of works (Lephart Hedges, 2003). Most of the patients with Alzheimers disease showed episodic memory loss, semantic memory loss and depressed irritation (Ka Birkha, 2000). In the brain of an Alzheimers patient, the episodic memory loss is related to severe pathological changes within hippocampal and parahippocampal social systems of the medial temporal lobes (Hyman et al., 1984 as cited in Ka Birkha, 2000) and to a deficiency in the neurotransmitter acetylcholine (Coyle et al., 1983 as cited in Ka Birkha, 2000). In 1975, a pioneer study in rats found that oestrogen upregulates the activity of choline acetyltransferase in the rats brain (Luine, Khylchevskaya, McEwen, 1975). later on ten years, another study confirmed that the activity of choline acetyltransferase in the medial aspect of the horizontal diagonal band nucleus, the frontal cortex, and cornu ammo nis 1 (CA1) of the dorsal genus Hippocampus were increased after the administration of oestrogens (Luine, 1985). Furthermore, the human nucleus basalis of meynert (a telencephalic structure that provides most of the acetylcholine to the cerebral cortex) in Alzheimers disease has been noticed the upregulation of oestrogen receptors (Behl, 2002). Thus, many studies project the use of oestrogens as a treatment of Alzheimers disease, as in fact, oestrogens increases the activity of acetylcholine, promotes the growth of neurons and their connections, enhances blood flow in the brain and seems to constrain the toxic effect of -amyloid (Alzheimers disease recent progress and prospectsPart II., 2001). However, the prominent reason in the treatment of Alzheimers disease with oestrogens is the low rate of Alzheimers disease in women who after menopause had used the hormone backup man therapy (Alzheimers disease recent progress and prospectsPart II., 2001). Despite of this fact, some studies showed that the use of oestrogen replacement therapy (ORT) had no improvement of the cognition and no halts the degeneration of women with Alzheimers disease (Larkin, 2000). Because of the changes of oestrogens during the women lifespan, some studies suggest that there is a critical cartridge holder related to start the hormonal replacement therapy to have an effect in Alzheimers disease (Brinton, 2004 Ka Birkha, 2000 Pettit, 2013). Thus, oestrogen changes is not only affects women with Alzheimers disease, nevertheless also the executive functions in all women during their lifespan.Oestrogen is commonly known as female sex hormone, and there are three types of oestrogen, the 17-oestradiol, oestrone and oestriol (Darlington, 2002). There are two other types of sex hormones, the male sex hormone testosterone, and the pregnancy hormone progesterone. The release of these hormones are determineled by the hypothalamus through the secretion of gonadotropin-releasing hormone which ac ts on the anterior pituitary gland to stimulate the release of the follicle-stimulating hormone and luteinising hormone (Darlington, 2002). During the female lifespan the levels of oestrogens change, such as catamenial cycle, pregnancy and menopause (Pettit, 2013). The catamenial cycle occurs during puberty and last until menopause, except during pregnancy. The ovulation occurs when there is a peak in the release of luteinising hormone, this hormone regulates the secretion of oestrogen, which in conjunction with the follicle-stimulating hormone control the development of the follicle (Darlington, 2002). The oestrogen levels reaches the peak during ovulation phase (mid cycle) and the bottom during the menstrual phase (bleeding), during menstrual cycle (Pettit, 2013). In the pregnancy the levels of oestrogens also gradually change, they reach a peak by the third trimester of the pregnancy, and this peak will be the highest level of oestrogen in the female lifespan. On the other hand, the lowest level of oestrogen in a female lifespan will be the menopause, when the levels of oestrogens decline both in the brain and in the body (Melton, 2000 as cited in Pettit, 2013). The distinction of the female physiology is this cyclic rise and fall of hormones levels (Darlington, 2002).Furthermore, oestrogen is not only responsible for reproductive functions, it has a role on the peripheral and central restless systems, and it also affects the development, growth, differentiation, maturation and function of several tissues in the body (Behl, 2002).Some studies had investigated the differences between men and women and concluded that most of the differences in the brain mechanism and structure is related to oestrogens the structural, cellular, and molecular differences in the brain is called true dimorphisms (Gillies McArthur, 2010). The main areas of the brain that are affect by these differences are the hippocampus, amygdala and cortex, which are responsible for the memo ry and cognition (Kelly et al., 1999 Baron-Cohen et al., 2005 as cited in Gillies McArthur, 2010). Additionally, oestrogen receptors are also found in astrocytes and other types of glial cell in the hypothalamus, the amygdala, the preoptic area, and the forebrain are the highest levels of oestrogen receptors expression and the oestrogen receptors density is greater in the hypothalamus than in extra hypothalamic regions, for instance the hippocampus and the cerebral cortex (Behl, 2002).To investigate how the fluctuations of oestrogen affect both the neuropsychological and neurophysiological parameters, and to visualise changes during the menstrual cycle, a study has use a functional magnetic resonance imaging (fMRI) to image cortical activation patterns associated with cognitive and motor activation. The results showed that in both neuropsychological tasks blood oestrogen level had a profound effect on the size but not on the lateralisation or the localisation of cortical activation patterns moreover a noticeable increase in perfusion in cortical areas voluminous in both cognitive tasks was noticed during the oestrogen peak in the female brain (Dietrich et al., 2001). Another study also investigate the oestrogen fluctuations during the menstrual phase, the results suggested that when the oestrogen are in their peak, some regions show enhanced activation one of these regions was the cortical region, which is has a connection with auditory and linguistic functions, which mean that surplus functional networks are recruited (Schning et al., 2007). Craig and collegues (2008) stated that women in specific times of their lives, (for instance childbirth, and around menopause), commonly complain of memory problems, which are related with oestrogen changes their results showed that a biological justification for previous reports might be the higher oestrogen levels, which is associated with improvement of verbal memory performance during the normal menstrual cycle.The refore, the main problem of the oestrogen changes is the menopause, where the oestrogens levels drastically fall. Evidence from a study showed an executive dysfunction in a women at menopause without hormonal replacement therapy, the results also suggested that the jailbreak of cognitive processes is promoted by the frontal lobes rather than the hippocampus additionally, oestrogen improves the execution of working memory tasks and the prefrontal cortex is essential for full working memory (Keenan, Ezzat, Ginsburg, Moore, 2001). A longitudinal study showed significant differences in regional cerebral blood flow during the memory tasks between women on ORT and women without, also women on ORT had ameliorate performance on neuropsychological tests of figural and verbal memory (Resnick, Maki, Golski, Kraut, Zonderman, 1998). Hence many studies had showed the improvement of executive functions, memory and attention on the ORT for women in menopause, until now there is a crucial tim ing to start the ORT, the critical period hypothesis. The oestrogen need to be taken when neurological health is still intact to have positive effects, before or at the time of menopause, otherwise if the replacement start after menopause, it can have harmful effects (Rettberg, Yao, Brinton, 2014).In conclusion, oestrogen is very important to the best functioning of the female brain. Executive functions, memory and attention are especially related to the levels of oestrogen. During the female lifespan the levels of oestrogens naturally change, reaching the peak on the third trimester of pregnancy and the lowest levels at menopause. Many studies showed the importance of the oestrogen replacement therapy, not only to alleviate the menopause symptoms but especially on the improvement of cognition. However there is the critical period hypothesis, which suggest that the time to start the ORT is before or at the time of the menopause to have the beneficial effect of it. Although there is a relation between low oestrogen levels and Alzheimers disease, evidences showed that the use of OTR in Alzheimers patients had no improvement. Finally, oestrogens and time are together, and the crucial timing to start the OTR can modify a life, the importance of future researches in this area is to provide a kick downstairs future for women and maybe decrease the numbers of Alzheimers patients.