evolutionary biology & mental illness

Anxiety is a fairly universal trait in humans and anyone who knows about the stress responses in the human body can understand the deep biological origins of them. Bipolarism and schizophrenia, on the other hand, are not 100% genetic, so it isn't clear to what degree they could be influenced by evolution.

 

I love evolutionary biology, it makes so much sense!

 

I think it would depend on the degree of the disorders. It's already been found that schizophrenia and bipolar disorders are both genetic. Other things can act as catalysts for latent psychological disorders as well(Read: LSD and schizophrenia). I thought they discovered that schizophrenia was due to higher dopamine levels in the brain?

Either way, schizotypal personality disorder being a learning mechanism would make sense. Where it starts to get shoddy is the varying degrees, different catalysts, nurture and genetics. If someone that's predisposed for schizophrenia lives in a house where they're beaten, has a job they hate, isn't happy with life at all and decides to drop acid- Things can end up pretty bad. Permanent psychological and neurochemical imbalance isn't as fun as it sounds.

The questions are: To what degree does the genetics of a person effect the possibility of them having psychological disorders? And is it nurture or the way they handle the condition that varies the degrees of psychosis or(this is a technical term) mindfuck?

 

Incorrect. It's been found that there is a correlation between a person's genetics (their family) and whether or not they develop these mental illnesses. Correlation is not cause.

For example, studies have found that there is a much higher probability within identical twins to both be schizophrenic if one of them is, however it is not the case 100% of the time. That indicates that genetics could very well play a factor, but it does not indicate that the condition is genetic itself.

 

I never said the cause was simply genetics but it's relatively obvious that it plays a role.

 

They do but as I originally said, they are not 100% genetic, and therefore, the degree to which evolution has played a role is indeterminable. These conditions are not comparable to anxiety which is virtually universal among humans.

 

Read:

 

They're both pretty genetic. A recent study in Sweden showed that bipolar (at least bipolar type I or manic-depression) and schizophrenia come from the same genes, which I found interesting, since both "illnesses" gallop through my family. For example, my grandmother and uncle had schizophrenia, while my mother had bipolar type I and a "normie" sister. I have manic-depression while my son has schizophrenia. He has a "normie" brother. They're genetic enough that scientists can predict with some accuracy the chances of passing on one or both of these "illnesses" to offspring. Of all the people I know with either bipolar or schizophrenia, ALL have someone else in the family with one or the other of the conditions, whether it be a grandparent, uncle, first cousin, etc. Now of course this isn't a scientific study; I'm just saying I've never known or even heard of anyone who is the only person in the family with mental illness. That doesn't mean there aren't any; I just don't know of any and I've studied the genetics of both "illnesses" pretty extensively.

All that aside, I found the article interesting and I loved the video in bi-chronicity because it so accurately depicts my perceptions during mood episodes. John McManamy, the guy in the video and author of the article, once sent out 100 MBTI tests to people with bipolar who subscribe to his newsletter. What he found was interesting: 14% came back as INFJs and 17% were INTPs; the only Es represented were ENFJs and I can't remember the percentage. In other words, some fairly rare types were way overrepresented, at least in this small, albeit unscientific study.

Most of this is speculative and anecdotal, but I still find it fascinating.

 

I know. The premise didn't match the conclusion. My Ti is like a rabid dog when it comes to discrepancy.

 

Maybe those types are just more likely to subscribe to that newsletter.

 

Could be. Certainly all had a confirmed diagnosis of bipolar, which is one reason they subscribe to the newletter, so to me that seems to beg the question. As I said, it's not exactly a scientific study, though I still thought the findings interesting.

There was even some comment--I think on the website--about a chicken-and-egg effect; i.e., am I bipolar because I'm an INFJ or am I an INFJ because I'm bipolar? Wish I could find the link.

 

Studies have also shown that genetics are responsible for a predisposition to, say schizophrenia, but that without significant stressors early in life, a person may never develop the condition, making it a combination of nature and nurture. The cause would then be a combination of genetics and early stressors, but genetics still plays a significant role; i.e., someone without a genetic predisposition to either disorder might be damaged by, say, childhood abuse but wouldn't develop schizophrenia or bipolar.

 

While searching for a link to some of my earlier research, I ran across this, which supports Satya's contention that genetics is not the sole cause of mental illnesses like bipolar and schizophrenia. I thought I should include it to be fair and complete. Here's the link: http://www.everydayhealth.com/bipolar-disorder/causes-of-bipolar-disorder.aspx. There's another article on the same site called Epigenetics that bears reading and offers some clarification on the whole genetics question. I think you can get to it from this link, but if not--and anyone is interested in it, I'll find the link..