martes, 19 de mayo de 2015

Teen cannabis users have poor long-term memory in adulthood

Teens who were heavy marijuana users -- smoking it daily for about three years -- had an abnormally shaped hippocampus and performed poorly on long-term memory tasks, reports a new study. The hippocampus is important to long-term memory, which is the ability to remember life events. The brain abnormalities and memory problems were observed during the individuals' early twenties, two years after they stopped smoking marijuana.


Teens who were heavy marijuana users -- smoking it daily for about three years -- had an abnormally shaped hippocampus and performed poorly on long-term memory tasks, reports a new Northwestern Medicine study.
The hippocampus is important to long-term memory (also known as episodic memory), which is the ability to remember autobiographical or life events.
The brain abnormalities and memory problems were observed during the individuals' early twenties, two years after they stopped smoking marijuana.
Young adults who abused cannabis as teens performed about 18 percent worse on long-term memory tests than young adults who never abused cannabis.
"The memory processes that appear to be affected by cannabis are ones that we use every day to solve common problems and to sustain our relationships with friends and family," said senior author Dr. John Csernansky, the Lizzie Gilman professor and chair of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine and Northwestern Memorial Hospital.
The study will be published March 12 in the journal Hippocampus.
The study is among the first to say the hippocampus is shaped differently in heavy marijuana smokers and the different looking shape is directly related to poor long-term memory performance. Previous studies of cannabis users have shown either the oddly shaped hippocampus or poor long-term memory but none have linked them.
Previous research by the same Northwestern team showed poor short-term and working memory performance and abnormal shapes of brain structures in the sub-cortex including the striatum, globus pallidus and thalamus.
"Both our recent studies link the chronic use of marijuana during adolescence to these differences in the shape of brain regions that are critical to memory and that appear to last for at least a few years after people stop using it," said lead study author Matthew Smith, assistant professor of psychiatry and behavioral sciences at the Feinberg School of Medicine.
The longer the individuals were chronically using marijuana, the more abnormal the shape of their hippocampus, the study reports. The findings suggest that these regions related to memory may be more susceptible to the effects of the drug the longer the abuse occurs.
The abnormal shape likely reflects damage to the hippocampus and could include the structure's neurons, axons or their supportive environments.
"Advanced brain mapping tools allowed us to examine detailed and sometimes subtle changes in small brain structures, including the hippocampus," said Lei Wang, also a senior study author and an assistant professor of psychiatry and behavioral sciences at Feinberg. The scientists used computerized programs they developed with collaborators that performed fine mappings between structural MRIs of different individuals' brains.
Subjects took a narrative memory test in which they listened to a series of stories for about one minute, then were asked to recall as much content as possible 20 to 30 minutes later. The test assessed their ability to encode, store, and recall details from the stories.
The groups in the study started using marijuana daily between 16 to 17 years of age for about three years. At the time of the study, they had been marijuana free for about two years. A total of 97 subjects participated, including matched groups of healthy controls, subjects with a marijuana use disorder, schizophrenia subjects with no history of substance use disorders, and schizophrenia subjects with a marijuana use disorder. The subjects who used marijuana did not abuse other drugs.
The study also found that young adults with schizophrenia who abused cannabis as teens performed about 26 percent more poorly on memory tests than young adults with schizophrenia who never abused cannabis.
In the U.S., marijuana is the most commonly used illicit drug, and young adults have the highest -- and growing -- prevalence of use. Decriminalization of the drug may lead to greater use. Four states have legalized marijuana for recreational use, and 23 states plus Washington D.C. have legalized it for medical use.
Because the study results examined one point in time, a longitudinal study is needed to definitively show if marijuana is responsible for the observed differences in the brain and memory impairment, Smith said.
"It is possible that the abnormal brain structures reveal a pre-existing vulnerability to marijuana abuse," Smith said. "But evidence that the longer the participants were abusing marijuana, the greater the differences in hippocampus shape suggests marijuana may be the cause."
Other Northwestern authors include senior author Hans C. Breiter and coauthors Derin J. Cobia, James L. Reilly, Andrea G. Roberts and Kathryn I. Alpert.
The study was funded by the National Institute of Mental Health of the National Institutes of Health, grants R01 MH056584 and P50 MH071616.
Tomado de:Northwestern University. (2015, March 12). Teen cannabis users have poor long-term memory in adulthood. ScienceDaily. Retrieved May 19, 2015 from www.sciencedaily.com/releases/2015/03/150312082906.htm

lunes, 4 de mayo de 2015

LUPUS ESRITEMATOSO SISTEMICO

CLASE LUPUS ERITEMATOSO SISTEMICO
COAGULACION Y ALTERACIONES VASCULARES
ROTACION PATOLOGIA CLINICA
ABRIL 2015

jueves, 30 de abril de 2015

La risa disminuye los niveles de hormonas asociadas con el estrés

Según un estudio de la Universidad de Maryland, las personas que han padecido un infarto del miocardio ríen hasta un 40% menos que las personas sin ese antecedente.

La risa, al igual que el llanto, es un acto involuntario para la mayoría de las personas. Su mecanismo de funcionamiento reside en la respiración, y se produce mediante interrupciones de la exhalación del aliento. Este proceso activa, además del sistema respiratorio, otros sistemas de nuestro organismo, como son el neurológico y el cardiovascular., según recuerda la Fundación Española del Corazón (FEC).

El efecto de la risa en nuestro sistema cardiovascular es vasodilatador; la risa genera  endorfinas, que producen un estado de bienestar psicológico, de tal manera que ésta ayuda a proteger el aparato cardiovascular. Cuando reímos, el endotelio  se relaja, mejorando así la circulación de la sangre y disminuyendo la presión arterial.

El Dr. José Luis Palma Gámiz, vicepresidente de la FEC, afirma que "la risa y la actitud positiva frente a la vida son beneficiosas para la salud cardiovascular. Por el contrario, los estados de estrés producen alteraciones en la pared vascular y favorecen la aparición de arteriosclerosis". El doctor Palma añade que “el estrés permanente condiciona la presencia de sustancias  vasoconstrictoras que afectan al endotelio y facilitan  que  el colesterol, penetren en la pared interior de los vasos sanguíneos, dando lugar a distintas enfermedades cardiovasculares”.
Reír también ayuda a aumentar el HDL  y potencia la actividad de los linfocitos. Reír reduce, además, el nivel de hormonas asociadas al estrés y aumenta el nivel de óxido nítrico, por lo que mejora la circulación, reduce la inflamación  y previene la formación de placas de colesterol.

Según explica el Dr.Palma, “el óxido nítrico es el vasodilatador natural más potente que se conoce. Cuando actúan conjuntamente sustancias como la serotonina y el óxido nítrico se producen las condiciones óptimas para una mayor vasodilatación, especialmente en los pequeños vasos sanguíneos, y, por tanto, disminuye la posibilidad de que se produzca una alteración del endotelio”.

Diferencia diametrial arterial

Son varios los estudios que han constatado beneficios de la risa en nuestro sistema cardiovascular. uno de ellos, realizado por la Unidad de Cardiología Preventiva del Centro Médico de la Universidad de Maryland, demostró que las personas que han sufrido un infarto agudo de miocardio ríen hasta un 40% menos que las personas que no han sufrido ningún tipo de enfermedad cardiovascular.

Este mismo centro realizó otro estudio en el que sometió a los participantes a situaciones cómicas y estresantes a través del visionado de películas. Tras analizar su reacción fisiológica, se comprobó que la diferencia diametral arterial entre estas dos situaciones opuestas oscilaba entre un 30% y un 50%. Así, en el caso de las películas estresantes, las arterias se contraían dificultando el aporte sanguíneo y aumentando el riesgo de sufrir problemas cardiovasculares, mientras que en situaciones cómicas, se dilataban, mejorando así la circulación de la sangre.

El Dr. Palma recuerda, por último, que “estar en paz con uno mismo y con su entorno y tener una actitud positiva frente a la vida, viendo los aspectos buenos, ayuda a prevenir las enfermedades cardiovasculares".

Tomado de: Jano.es

CLASE TRASTORNOS DE LA HEMOSTASIA EN HEPATOPATIAS

CLASE TRASTORNOS DE LA HEMOSTASIA EN HEPATOPATIAS
ROTACIONPATOLOGIA CLINICA
ABRIL 2015