#etiologi     #mani     #samhälle     #studie     #depression     #diagnostik     #psykologi     #artikel     #stämningsläge     #läkemedel     #hjärnan     #myt     #neurologi     #npf     #perception     #psykos     #attityder     #stigma     #ångest     #mindhacks  
Nytt sedan sist

Load Newest Topics
Topics Since Last Visit
Skaffa Appen

Aktuell tid och datum: mån nov 23 2020, 18:15

2 träffar

Motståndskraft mot stress, vad är det och vart kommer det ifrån?

Nature skrev:Confronted with a life-threatening situation, hormones and neurotransmitters prep us for action. Specific stress hormones — cortisol in primates, corticosterone in most rodents — are released, some of which surge across the blood–brain barrier. Stress gets everywhere: all our cells host receptors for the hormone. “Every brain area has something happen to it,” says Kaufer. The human brain has two types of receptor for cortisol. One has a six to tenfold higher affinity for the molecule than the other, and so is activated earlier, by smaller amounts of cortisol.

The hippocampus (which is pivotal for memory) and the amygdala (the centre for emotions) contain lots of the high-affinity receptors, and are, therefore, activated by slight rises in the hormone. The frontal lobe, which is involved in executive planning and control, has only the low-affinity receptor, and is activated later, after the tide has risen. And, as Lupien and colleagues found, both memory formation and recall in adults can be influenced by cortisol1.

The existence of two receptor types means that response to stress is not linear. “The relationship between circulating stress hormone and memory is an inverted U-shape function,” Lupien explains. “Up to a certain level, stress hormones are good for your memory” — when the cortisol binds only to the high-affinity receptors, the ability to lay down and retrieve memory is enhanced. When the low-affinity receptors are activated, the relationship enters the right-hand side of the U-shape and the response shifts, she adds.

The duration of stress is also important. A transient bout of stress causes a proliferation of neural stem cells and a spike in numbers of new neurons, which take at least two weeks to mature. The brain seems to be preparing itself in case a second stressor comes calling. Chronic stress is not so beneficial. It slashes investment in new neurons, prunes the tree-like shape of existing ones, and suppresses new connections.

If stress hormones remain elevated for months or years, they can stimulate physiological changes: the hippocampus shrinks and the amygdala grows, for example. Eventually, the complex feedback system that suppresses the excess secretion of cortisol is disturbed. Once this happens, the capacity to discriminate between threat levels falls away. Either everything seems threatening (anxiety) or else nothing does (depression or burnout).

Nature skrev:Old ideas that certain individuals have an inherent 'hardiness' or an innate ability to bounce back from severe stress have fallen by the wayside. Instead, resilience and our response to trauma are recognized as being more dynamic, changing throughout life. It's a complicated milieu, but one of the main ways that stress marks the brain is through epigenetics. This does not change genes, but it can change their expression by attaching methyl groups to DNA or associated proteins.

Nature skrev:As with memory, the way that sociability changes with stress is not linear. Kaufer's lab found that rats exposed to moderate stress — in this case, being immobilized in a bag — displayed more positive social behaviour, such as huddling, resource sharing and reduced aggression4. The researchers also saw an increase in the prosocial hormone oxytocin. But if the immobilized rats were exposed to fox odour, the addition of this high-level-stress inducer caused them to lose all pro-social behaviours. Oxytocin plummeted, as did its receptors. “This is really interesting because it can start to explain the social withdrawal that you can see in some psychopathologies like PTSD and depression,” Kaufer says.


#artikel #nature #stress #kortisol #neurologi #depression #minne #beteende #hjärnan
av Onddruid
i tor mar 03 2016, 11:18
Sök i: Nyheter
Ämne: Motståndskraft mot stress, vad är det och vart kommer det ifrån?
Svar: 0
Visningar: 1316

Bipolära patienter med utmattat stresshormonsystem


[2016-01-19] Nya rön visar att äldre bipolära patienter ofta har en sänkt aktivitet i hormonsystemet som styr utsöndringen av stresshormonet kortisol. Låga kortisolnivåer hos bipolära patienter visades också vara starkt förknippat med depression, låg livskvalitet, fetma, höga blodfetter och metabolt syndrom. Upptäckterna kan ge viktiga ledtrådar till hur behandlingsstrategier för depression och bipolär sjukdom kan förbättras, enligt en avhandling vid Umeå universitet

Stress medför normalt ökad aktivitet i hormonsystemet som reglerar utsöndringen av kortisol. Hyperaktivitet i hormonsystemet med höga kortisolnivåer, ett tillstånd som kallas hyperkortisolism, är vanligt förekommande vid depression. Men i andra änden av skalan finns exempel på att hög stress över lång tid kan leda till hypokortisolism.        

Det är möjligt att återkommande depressiva och/eller maniska perioder med hög ackumulerad stressbelastning med tiden leder till en utmattning av hormonsystemet. Stöd för denna hypotes sågs i gruppen med bipolära patienter där högre ålder var relaterat till lägre kortisolnivåer speciellt hos patienter som inte medicinerat med förebyggande stämningsstabiliserande medicinering. Däremot förekom ingen ökning av andelen med hypokortisolism bland de bipolära patienterna som under en stor del av livet medicinerat med den stämningsstabiliserande medicinen litium. Detta innebär enligt Martin Maripuu att den på sjukdomsförloppet gynnsamma effekten av tidigt insatt litiummedicinering delvis skulle kunna förklaras av att litium förebygger utvecklingen av hypokortisolism.

#studie #hjärnan #kortisol #litium #metabolt_syndrom #fetma #bipolär #depression
av chai
i tor feb 25 2016, 18:04
Sök i: Nyheter
Ämne: Bipolära patienter med utmattat stresshormonsystem
Svar: 3
Visningar: 1437

Till överst på sidan

Hoppa till: