Posted by alexandra_k on September 24, 2006, at 2:32:54 [reposted on September 25, 2006, at 0:09:10 | original URL]
In reply to Re: the brain » alexandra_k, posted by Phillipa on September 23, 2006, at 22:46:25
> I believe but could be mistaken that there are actual changes on MRI's or other imaging devises that show the brain of a schizophrenic is not the same as someone without it. Someone correct me if I'm wrong. Love Phillipa
If you take a bunch of people with a dx of schizophrenia
a, b, c, d, e, f, g,
And you neuroimage their brains...
Then around 14% have enlarged ventricles and correspondingly smaller other structural areas. I don't have the book with me... But I think it is around 14%. That isn't even *most* of them. Then what you find is around 7% of the control group (people who don't have schizophrenia) also have enlarged venrticles and correspondingly smaller other structural areas. I'm pretty sure that some of those people are considered *normal* controls in the sense that they haven't been dx'd with a mental illness and their behaviour doesn't meet criteria for one. Other patient controls have similar structural abnormalities but they don't have a dx of schizophrenia because their behaviour doens't meet criteria. Instead, they have another dx, such as bi-polar.Do you know what they do then?
They average the results of a, b, c, d, e, f, and g to come up with ONE image of a 'typical brain of a person with schizophrenia'. By 'typical' they don't mean 'if you have schizophrenia this is what your brain is likely to look like'. If you have schizophrenia your brain is more likely to look like a persons in the control group than it is likely to look like the 'typical brain of the person with schizophrenia'. Someone or other said 'it is easy to tell the brains of people with schizophrenia - they are the ones that look normal' because for the most part, they do.
But what is normal? That is a statistical notion again. Take a population of people without a dx of mental illness and neuro-image their brains. Then average the results so you have one image and there is your 'normal / typical brain'. Statistically speaking, even if you didn't have mental illness your brain would be abnormal if it were to look just like the 'normal / typical brain'. There is considerable variation across the non mentally ill population just as there is considerable variation across the mentally ill population just as there is considerable variation across the brains of a population dx'd with a particular disorder.
So when they say that people with schizophrenia have abnormal brains they don't mean that the majority of individuals with schizophrenia have abnormal brains.
So there is a significant problem with saying that abnormal brains cause schizophrenic behaviours / symptoms. The problem is that the majority of people with schizophrenia have normal brains (which is to say brains that fall within the range of normality and their brains can't be differentiated from people without mental illness).
Though things are more complicated...
More dopamine receptors on autopsy. But once again... *Some* people with schizophrenia not *all* and how many people without schizophrenia have more dopamine receptors on autopsy?
Perhaps the neuroimaging isn't detailed enough... Or perhaps sctuctural / neuro-transmission abnormalities aren't necessary or sufficient for schizophrenia... Or perhaps... Schizophrenia isn't a natural kind.
My understanding is that those with the 'abnormal' brains are those who display the most extreme negative symptoms that significantly interfeare with their lives. They might form a natural kind. But schizophrenia in general... Not likely.
poster:alexandra_k
thread:688931
URL: http://www.dr-bob.org/babble/social/20060922/msgs/688958.html