Are you sleeping restlessly, feeling irritable or moody, forgetting little things, and feeling overwhelmed and isolated? Don't worry. We've all been there. You're probably just stressed out. Stress isn't always a bad thing. It can be handy for a burst of extra energy and focus, like when you're playing a competitive sport, or have to speak in public. But when its continuous, the kind most of us face day in and day out, it actually begins to change your brain. Chronic stress, like being overworked or having arguments at home, can affect brain size, its structure, and how it functions, right down to the level of your genes. Stress begins with something called the hypothalamus pituitary adrenal axis, a series of interactions between endocrine glands in the brain and on the kidney, which controls your body's reaction to stress. When your brain detects a stressful situation, your HPA axis is instantly activated and releases a hormone called cortisol, which primes your body for instant action. But high levels of cortisol over long periods of time wreak havoc on your brain. For example, chronic stress increases the activity level and number of neural connections in the amygdala, your brain's fear center. And as levels of cortisol rise, electric signals in your hippocampus, the part of the brain associated with learning, memories, and stress control, deteriorate. The hippocampus also inhibits the activity of the HPA axis, so when it weakens, so does your ability to control your stress. That's not all, though. Cortisol can literally cause your brain to shrink in size. Too much of it results in the loss of synaptic connections between neurons and the shrinking of your prefrontal cortex, the part of your brain the regulates behaviors like concentration, decision-making, judgement, and social interaction. It also leads to fewer new brain cells being made in the hippocampus. This means chronic stress might make it harder for you to learn and remember things, and also set the stage for more serious mental problems, like depression and eventually Alzheimer's disease. The effects of stress may filter right down to your brain's DNA. An experiment showed that the amount of nurturing a mother rat provides its newborn baby plays a part in determining how that baby responds to stress later in life. The pups of nurturing moms turned out less sensitive to stress because their brains developed more cortisol receptors, which stick to cortisol and dampen the stress response. The pups of negligent moms had the opposite outcome, and so became more sensitive to stress throughout life. These are considered epigenetic changes, meaning that they effect which genes are expressed without directly changing the genetic code. And these changes can be reversed if the moms are swapped. But there's a surprising result. The epigenetic changes caused by one single mother rat were passed down to many generations of rats after her. In other words, the results of these actions were inheritable. It's not all bad news, though. There are many ways to reverse what cortisol does to your stressed brain. The most powerful weapons are exercise and meditation, which involves breathing deeply and being aware and focused on your surroundings. Both of these activities decrease your stress and increase the size of the hippocampus, thereby improving your memory. So don't feel defeated by the pressures of daily life. Get in control of your stress before it takes control of you.
Nemirno spiš, si razdražljiv in slabe volje, pozabljaš majhne stvari, se ti zdi, da si preobremenjen in izoliran? Ne skrbi. Vsi smo to že doživeli. Najbrž si samo pod stresom. Stres ni vedno nekaj slabega. Lahko je priročen za dodatni izbruh energije in osredotočenosti, kot na primer pri tekmovalnem športu ali javnem nastopanju. Ampak ko je stres neprestan, tak kot ga doživlja večina od nas vsak dan, dejansko začne spreminjati možgane. Kroničen stres, kot na primer zgaranost ali napetosti doma, lahko vpliva na velikost možganov, njihovo strukturo in funkcijo vse do genov. Stres se začne z osjo hipotalamus-hipofiza-nadledvične žleze (HPA), serijo interakcij med endokrinimi žlezami v možganih in nad ledvico, ki nadzorujejo odziv na stres. Ko možgani zaznajo stresno situacijo, je os HPA nemudoma aktivirana in sprosti kortizol, hormon, ki pripravi telo na takojšnjo akcijo. A visoka raven kortizola, ki traja dolgo časa, uniči možgane. Na primer, kronični stres poveča aktivnost in število nevronskih povezav v amigdali, možganskem centru za strah. Ko se raven kortizola dviga, se električni signali v hipokampusu, delu možganov, ki je odgovoren za učenje, spomine in nadzor stresa, uničijo. Hipokampus prav tako inhibira aktivnost HPA osi, tako da ko oslabi, z njim oslabi tudi sposobnost nadziranja stresa. To pa še ni vse. Kortizol lahko dobesedno skrči možgane. Če ga je preveč, se sinaptične povezave med nevroni izgubijo in prefrontalni korteks se skrči, to je del možganov, ki je odgovoren za nadzor koncentracije, odločanja, presoje, in socialnih interakcij. Prav tako to vodi v nastanek manj novih celic v hipokampusu. To pomeni, da kronični stres povzroči, da se težje učiš in si težje zapomniš stvari in prav tako lahko vodi v bolj resne duševne težave, kot je depresija in sčasoma Alzheimerjeva bolezen. Učinki stresa morda segajo vse do DNK. Poskus je pokazal, da količina nege, ki jo mati podgana nudi svojemu novorojenčku, igra pomembno vlogo v odzivu tega mladička na stres kasneje v življenju. Mladički z bolj ljubečimi mamami so bili manj občutljivi na stres, ker so njihovi možgani razvili več receptorjev za kortizol, ki se oprimejo kortizola in zmanjšajo odziv na stres. Mladiči neljubečih mam so imeli ravno nasproten izid in so tako postali bolj občutljivi na stres kasneje v življenju. To so epigenetske spremembe, kar pomeni, da vplivajo na izražanje genov, ne da bi vplivale direktno na genski zapis. In te spremembe lahko obrnemo, če zamenjamo mame. A tu je presenetljiv rezultat. Epigenetske spremembe, ki jih povzroči ena sama podganja mama, so se prenesle na mnoge generacije podgan za njo. Z drugimi besedami, posledice teh dejanj so bile dedne. Ni pa vse tako slabo. Veliko načinov obstaja, da spremenite učinek kortizola na možgane. najbolj močni orožji sta gibanje in meditacija, ki vključujeta globoko dihanje in zavedanje ter osredotočenost na svojo okolico. Obe aktivnosti zmanjšujeta stres in povečata velikost hipokampusa, in tako izboljšata spomin. Naj te pritiski v vsakdanjem življenju ne premagajo. Nadzoruj svoj stres, preden bo stres nadzoroval tebe.