ANDRÉS… EL QUE VIENE UNA VEZ POR MES


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ANDRÉS… EL QUE VIENE UNA VEZ POR MES

 

El período menstrual, ¿afecta el desempeño cognitivo de la mujer?

 

FILOSOFO_LP

04-07-2017

Fuente: Revista científica; Frontiers in Behavioral Neuroscience---- Publicación del 04-julio-2017

 

RESUMEN:

Esta nota es un extracto con comentarios agregados, de un ensayo científico publicado hoy martes 04 de julio de 2017, en la revista de la referencia, especializada en neurociencia conductual, en el que participaron investigadores de los siguientes centros de estudios:

1- Departamento de Endocrinología Reproductiva, Hospital Universitario Zürich, Zurich, Suiza
2- Departamento de Psiquiatría, Psiquiatría Social y Psicoterapia, Escuela de Medicina Hannover, Hannover, Alemania
3- Departamento de Informática, Sapienza Università di Roma, Roma, Italia
4- Centro de Competencia en Ciencia y Tecnología Aeroespacial, Biomédica, Universidad de Ciencias Aplicadas y Artes de Lucerna, Lucerna, Suiza
5- Computational Systems Biology Group, Instituto Zuse, Berlín, Alemania
6- Instituto de Química Clínica, Hospital Universitario de Zúrich, Zurich, Suiza
7- Departamento de Ginecología y Obstetricia, Escuela de Medicina de Hannover, Hannover, Alemania
8- Departamento de Psicología Aplicada, Universidad de Zurich para Ciencias Aplicadas (ZHAW), Zurich, Suiza

 

Sería redundante reiterar los clásicos síntomas menstruales y pre-menstruales por ser extensamente conocidos.

Pero un tema que siempre fue motivo de debates y lleno de mitos, ha sido determinar si durante ese período incómodo para la mujer, se halla afectada su capacidad intelectual o rasgos cognitivos.

Un equipo de investigadores, liderados por Brigitte Leeners, especialista en medicina reproductiva del Hospital Universitario de Zúrich, quien luego de estudios controlados en un importante número de mujeres, ha llegado a la siguiente conclusión:

"La función cognitiva de las mujeres no depende de los cambios hormonales que ocurren durante todo su ciclo menstrual”

A esta conclusión llegó con su equipo, luego de analizar los resultados en la variaciones de estrógenos y progesterona, donde observaron que estos cambios hormonales no tuvieron ningún impacto en la memoria a corto plazo necesaria para realizar tareas y procesar información, en la fluidez verbal, en los sesgos cognitivos o en la capacidad de prestar atención.

Ninguna de las hormonas estudiadas tuvo un efecto repetible y consistente en las capacidades cognitivas de las participantes del estudio.

Vale recordar brevemente que estas hormonas, intervienen no solamente en la función sexual y reproductora, sino en otras muchas actividades biológicas de la mujer.

Por ejemplo, los estrógenos, reguladores del ciclo menstrual, son hormonas derivadas del colesterol, y participan además en el metabolismo de los huesos, y por eso su relación con la osteoporosis al bajar su nivel en la menopausia; favorecen el oscurecimiento de la piel en pezones y zona genital; la distribución de la grasa corporal que hace típica la silueta femenina; la estimulación de la libido, la distribución del vello femenino en el inicio de la adolescencia etc.

Por su parte la progesterona, que prevalece en la segunda mitad del ciclo mensual, es producida por el ovario y fundamentalmente por el cuerpo lúteo después de la ovulación, es fundamental para estimular los cambios madurativos, preparando al endometrio (la mucosa que recubre el interior del útero) para receptar e implantar el embrión en el útero, en caso que la mujer quede embarazada.

Pero de acuerdo a este estudio publicado, estas hormonas no intervendrían en las capacidades intelectuales de la mujer.

La publicación ocupa varias páginas, pero aquí por razones obvias solo he esbozado un resumen con agregados míos ilustrativos, pero para quienes tengan interés en leer un poquito más sobre el estudio publicado, les dejo el “Abstract” del artículo de investigación original.

Original Research ARTICLE

04 July 2017

Lack of Associations between Female Hormone Levels and Visuospatial Working Memory, Divided Attention and Cognitive Bias across Two Consecutive Menstrual Cycles

Background: Interpretation of observational studies on associations between prefrontal cognitive functioning and hormone levels across the female menstrual cycle is complicated due to small sample sizes and poor replicability.

Methods: This observational multisite study comprised data of n = 88 menstruating women from Hannover, Germany, and Zurich, Switzerland, assessed during a first cycle and n = 68 re-assessed during a second cycle to rule out practice effects and false-positive chance findings. We assessed visuospatial working memory, attention, cognitive bias and hormone levels at four consecutive time-points across both cycles. In addition to inter-individual differences we examined intra-individual change over time (i.e., within-subject effects).

Results: Estrogen, progesterone and testosterone did not relate to inter-individual differences in cognitive functioning. There was a significant negative association between intra-individual change in progesterone and change in working memory from pre-ovulatory to mid-luteal phase during the first cycle, but that association did not replicate in the second cycle. Intra-individual change in testosterone related negatively to change in cognitive bias from menstrual to pre-ovulatory as well as from pre-ovulatory to mid-luteal phase in the first cycle, but these associations did not replicate in the second cycle.

Conclusions: There is no consistent association between women's hormone levels, in particular estrogen and progesterone, and attention, working memory and cognitive bias. That is, anecdotal findings observed during the first cycle did not replicate in the second cycle, suggesting that these are false-positives attributable to random variation and systematic biases such as practice effects. Due to methodological limitations, positive findings in the published literature must be interpreted with reservation.

Introduction

In the scientific literature, female sex hormones and the menstrual cycle have been linked to cognitive performance (Farage et al., 2008; Sherwin, 2012). The main tenet of this work is that sexually dimorphic cognitive skills that favor men (i.e., visuospatial tasks) are improved during menstrual phases with low estrogen and/or progesterone, while skills that favor women (i.e., verbal tasks) are improved during phases of high estrogen/progesterone. This work has been extended to test prefrontal cortex functions and along these lines it has been suggested that estrogens may be significantly involved in attention and working memory (e.g. Solis-Ortiz and Corsi-Cabrera, 2008; Hatta and Nagaya, 2009; Jacobs and D'Esposito, 2011). However, a variety of studies found no or inconsistent associations, as recently detailed in a comprehensive review and synthesis of the literature (Sundstrom Poromaa and Gingnell, 2014). Moreover, there are growing concerns that various positive associations reported in the literature could be true null associations, that is, methodological artifacts and chance findings (Ioannidis, 2005; Rosmalen and Oldehinkel, 2011; Ferguson and Heene, 2012; Hengartner, 2017). In support of this notion it has been demonstrated that due to scientific biases, first, false-positive findings are ubiquitous, second, that inflated effect sizes are common and, third, that the reproducibility of results is generally low in psychological and biomedical research (e.g., Kriegeskorte et al., 2009; Prinz et al., 2011; Ritchie et al., 2012; Button et al., 2013; Macleod et al., 2014; Open Science Collaboration, 2015; Muller et al., 2017). The ongoing question is therefore, whether the fluctuations of female sex hormones across the menstrual cycle really influence attention and working memory in a consistent way or whether these positive findings are spurious false-positives due to scientific fallacies and methodological biases.

As recently reviewed, most published studies failed to find meaningful and consistent associations between hormones and cognitive functioning in women (Sundstrom Poromaa and Gingnell, 2014). One reason for the inconsistencies between findings is that cross-sectional studies (e.g., Halari et al., 2005; Hampson and Morley, 2013) do not allow for drawing stringent conclusions and that many longitudinal studies relied on only two measurements (e.g., Maki et al., 2002; Schoning et al., 2007; Hatta and Nagaya, 2009; Jacobs and D'Esposito, 2011). An additional major source of bias within the field are the utterly small sample sizes, which commonly include less than 30 women (e.g., Maki et al., 2002; Schoning et al., 2007; Jacobs and D'Esposito, 2011), and in some highly-cited studies even less than 10 (e.g., Hausmann et al., 2000; Solis-Ortiz et al., 2004; Solis-Ortiz and Corsi-Cabrera, 2008). As comprehensively reviewed by Button et al. (2013), underpowered small samples substantially undermine the reliability of research findings by producing severely inflated effect sizes and both false-positive and false-negative results. Various studies also made speculative inferences from cycle phase on hormone levels without actually reporting a correlation between hormones and cognition (e.g., Rosenberg and Park, 2002; Solis-Ortiz et al., 2004; Solis-Ortiz and Corsi-Cabrera, 2008). Such inferences are problematic because inter-individual variance in hormone levels at particular phases of the cycle is tremendous (Sundstrom Poromaa and Gingnell, 2014). That is, it must not be concluded that inter-individual differences between cognitive functioning and cycle phase is causally related to estrogen simply because, for instance, estrogen is on average higher around ovulation than premenstrually, since a substantial portion of women have higher estrogen levels premenstrually than at ovulation. A stringent test would be to examine whether intra-individual change from ovulatory to premenstrual phase relates to changes in cognitive functioning. If not, then a causal relationship is unlikely, but unfortunately intra-individual change has hardly been considered in this field. Of major concern are also reporting and publication biases, which prevent the dissemination of negative findings and which lead to severe overestimation of associations in the published literature (Ioannidis et al., 2014). Thus, there is apparently a gap between the actual meaning of research findings and conclusions drawn in some narrative reviews and original studies. In view of the methodological shortcomings in the literature on associations between hormones and cognitive abilities detailed above, methodologically sound observational studies are necessary.

To come at reliable and valid estimates, larger samples (i.e., preferably n > 50) more fine-grained designs (i.e., 4 repeated measurements across the cycle), more sophisticated statistical modeling (examination of intra-individual change) and replication of results (i.e. using data from a second cycle) are required. We thus postulate the following four propositions for a reliable and meaningful finding: Firstly, there needs to be evidence for significant differences in cognitive functioning across the cycle (inter-individually and specifically intra-individually). Secondly, between-subject differences in hormone levels must relate to differences in cognitive abilities at specific cycle phases. Thirdly, these effects need to replicate in significant associations between intra-individual change in hormone levels and cognitive abilities across the cycle. Fourthly, significant effects must replicate in data obtained from a second menstrual cycle to exclude practice effects and false-positive chance findings. The aim of the present work was to critically examine, whether prefrontal cortex functions such as working memory, attention and cognitive control relate to serum hormone levels. A recent review suggested that these cognitive functions may correlate positively with estrogen and progesterone (Sundstrom Poromaa and Gingnell, 2014), but due to the inconsistencies and methodological limitations in the literature on associations between cognitive functioning and hormones detailed above, we did not a priori postulate specific hypotheses.


 

 

Comentarios

@LADYDY

05/07/2017

 
@NORSU

07/07/2017



Wow! Very impresive. Are you happy now??  
@FILOSOFO_LP

27/07/2017



@NORSU

Ahora NO… ya venía siendo feliz desde antes, pero en estos momentos estoy de vacaciones.

FILOSOFO_LP

27-07-27  

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