تفاوتهای جنسیتی در حافظه اپیزودیک: نفوذ حداقل استرادیول
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|33597||2003||8 صفحه PDF||سفارش دهید||4899 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Brain and Cognition, Volume 52, Issue 2, July 2003, Pages 231–238
Sex differences exist for several cognitive tasks and estrogen has been suggested to influence these differences. Eighteen men and 18 women were matched on age and estradiol level. Potential sex differences were assessed in episodic memory, semantic memory, verbal fluency, problem solving, and visuospatial ability. Significant sex differences, favoring women, were found for tasks assessing episodic memory. Correlations between estradiol level and cognitive performance were significant for face recognition in females. Since sex differences remained in verbal episodic memory tasks and face recognition despite matched levels of estradiol, circulating estradiol does not appear to be of paramount consequence for observed sex differences in episodic memory.
Sex differences have been well established in several cognitive spheres since the seminal work of Maccoby and Jacklin in 1974 (Halpern, 1992 and Halpern, 1997). Men typically excel in spatially oriented tasks whereas women usually have better verbal fluency (Hyde & Linn, 1988; Voyer, Voyer, & Bryden, 1995). In the domain of memory, sex differences have been reported in episodic memory with women typically outperforming men (see Herlitz, Nilsson, & Bäckman, 1997). Women outperform men on episodic memory tasks when the to be remembered items are words (Hill et al., 1995; Kramer, Delis, & Daniel, 1988), stories (Hultsch, Masson, & Small, 1991), concrete pictures (Herlitz, Airaksinen, & Nordström, 1999), faces (Herlitz & Yonker, 2002; Lewin & Herlitz, 2002; Wahlin et al., 1993), locations (Eals & Silverman, 1994), and odors (Lehrner, 1993). These differences are consistent across ages ranging from 5 (Kramer et al., 1988) to 75 (Herlitz et al., 1997). However, no sex differences are found on non-verbal episodic memory tasks, and men outperform women when the to be remembered items are visuospatial in nature (Lewin, Wolgers, & Herlitz, 2001). The precise explanation for the obtained sex differences in episodic memory is not known, although biological factors are believed to have some influence on the differences. For example, sex differences have been found with respect to brain activation in recent PET studies (Nyberg, Habib, & Herlitz, 2000; Ragland, Coleman, Gur, Glahn, & Gur, 2000). Nyberg and colleagues examined sex differences and episodic memory and found that, even though there was an overlap in male and female brain activation patterns, subtle activation and deactivation differences were apparent between men and women. Others have found that resting activity in the left temporal lobe was positively associated with episodic memory performance in women (Ragland et al., 2000). In addition, there is some evidence indicating that fluctuating hormone levels influence cognitive performance. For example, a few studies have found that young women performed at a higher level on visuospatial tasks when estrogen levels were lower, than when estrogen levels were higher (Hampson, 1990; Hausmann, Slabbekoorn, Van Goozen, Cohen-Kettenis, & Gunturkun, 2000; Postma, Winkel, Tuiten, & van Honk, 1999). However, studies of endogenous estrogen in postmenopausal women have not always found an association between cognition and endogenous estrogen (Barrett-Connor & Goodman-Gruen, 1999; Yaffe, Grady, Pressman, & Cummings, 1998a), and research investigating the contribution of hormone replacement therapy (HRT) on cognitive performance in postmenopausal women has yielded conflicting results. Some studies reported beneficial effects of HRT on cognition (Kampen & Sherwin, 1994; Kimura, 1995; Maki, Zonderman, & Resnick, 2001; Robinson, Friedman, Marcus, Tinklenberg, & Yesavage, 1994; Sherwin, 1988), whereas other studies have reported no effect of HRT on cognition (Barrett-Connor & Kritz-Silverstein, 1993). Taken together, the results from both controlled trials and observational studies are difficult to interpret, due primarily to methodological inconsistencies (Haskell, Richardson, & Horwitz, 1997; Hogervorst, Williams, Budge, Riedel, & Jolles, 2000; Yaffe, Sawaya, Lieberburg, & Grady, 1998b) Even though results from behavioral studies examining estrogen and cognition have been inconsistent, basic animal research clearly demonstrates estrogen’s impact on the brain, particularly on systems that could be important for memory functions. Estrogen influences neurotransmission in the brain by stimulating a significant increase in both dopamine2 receptors and density of serotonin binding sites (Fink, Sumner, Rosie, Grace, & Quinn, 1996). Estrogen increases dendritic spines in the hypothalamus and the hippocampus (McEwen, Alves, Bulloch, & Weiland, 1997; McEwen & Woolley, 1994), increases synaptic plasticity (Naftolin, Leranth, Perez, & Garcia-Segura, 1994), and enhances neuronal growth (Brinton et al., 1997a and Brinton et al., 1997b). These animal studies suggest that estrogen can play a role in cognitive abilities, however, the precise mechanism of estrogen’s action on cognitive functions has yet to be determined. Guided by persistent sex differences in verbal episodic memory performance and findings from the estrogen research domain, we aspired to better understand the contribution of active estradiol on sex differences in episodic memory by examining endogenous estradiol levels in older men and women. Men and women were matched on estradiol level, thereby keeping constant one possible contributor to the sex differences in episodic memory (Herlitz et al., 1997; Hill et al., 1995; Schaie & Willis, 1993; Zelinski, Gilewski, & Schaie, 1993). Therefore, if circulating estradiol is a major contributor to sex differences in episodic memory, we hypothesized that men and women with similar estradiol levels should exhibit similar episodic memory performance.