Stressed Linked

As mentioned in my last post, I had been meaning to write about something my biology teacher talked about one day. What he said was only a glimpse into the topic, much of which is still unknown; however it makes a lot of sense. I wanted to do a bit more research, and here are some of my findings and thoughts.

The main idea is that stress is linked to depression. Increased levels of stress cause and increase in depression; the increase in depression inhibits important processes in the brain (including serotonin and norepinephrine reception). Because the increased depression and decreased neural reception, more stress is perceived, and thus more depression occurs. This creates one nasty spiral of stress and depression.

So far, using General OneFile, a database made available by the VT libraries, I have found an interesting article about this theory (and the way antidepressants work) tested on mice. You can read the full article here. The part I find to be the highlight of the article describe the role of new neurons. Anti-depressants stimulate the growth of neurons, which repair reception and alleviate depression (or at least thats what theory states). Suggesting anti-depressants work in this manner makes a lot of sense considering the time need for the anti-depressants to take effect. Chemically the change should take place in a matter of a few hours, much in the same way pain killers or other drugs work. However, anti-depressants usually take around two weeks to show a change. The time lapse could account for the neurogenesis taking place- which accounts for the decrease in depression. Another article supports the theory neurogenesis of neurons in the hippocampus. (This article is much more complicated to read, just a warning.) The article discusses the way neurons are effected, and the role neurons play, in long term depression.

Both of these articles support the importance of the hippocampus, which plays a role in long term memory and spatial navigation. (Interestingly the hippocampus is the first area to undergo deterioration in Alzheimer's Disease, and has connections to encephalitis, both other diseases I'm really interested in.) Although there is much that is still unknown about the hippocampus, it is agreed that it has a major role in creating new memories. A study linked the hippocampus' deterioration to depression, and the regeneration of the hippocampus under antidepressants. There is still much debate to whether the depression caused the neurons to cease to work, or if the hippocampus' deterioration triggered depression.

I find it interesting that the memory center of our brains is linked to depression. The correlation of stress and increased depression, with memory, makes sense. If you are undergoing large amounts of stress, there should be negative effects on the way your forming memories- the thoughts your having are not calm and thus the memories your forming would not necessarily be pleasant. The decrease in a euphoric feeling can lead to feelings of depression- the hopelessness, sadness, etc. Once the depression is triggered, the amount of stress rises, and the increase in negative memories. The deterioration of neurons also seems fitting. Because you are stressed, the neural activity is working at a much more labored rate. Like everything else in your body, it make sense that neurons could simply burn out. Less neurons = more stress = more depression = ongoing downward spiral. At least, thats my take on the whole thing... All and all, I have to say this is some really interesting stuff- and hopefully we'll find more out more about it in the next few years.