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How Schizophrenia Is Diagnosed

Learn how schizophrenia is diagnosed from psychiatrist Jeanie Tse in this Howcast video.


Hi. I'm Jeanie Tse, and I'm here to talk to you about how schizophrenia is diagnosed. There's no lab test or radiological X-ray test for schizophrenia. The way we diagnose is using a clinical interview and also information from other people that might know a person to know whether they have the symptoms and signs of schizophrenia.

So, there are psychological tests that sort of tell you about your general personality structure and whether you might have a risk for psychotic symptoms, but they are also not definitive ways of diagnosing schizophrenia. It's really that interview that it comes from, as well as the person's history. And so, the Diagnostic and Statistic Manual, which is the compendium in psychiatry that tells us all the symptoms and criteria for different disorders, talks about schizophrenia. And it recently changed over from DSM IV to DSM V in May of this year, of 2013. And the criteria are largely the same.

What's changed is that some of the sub-types have been eliminated because they didn't hold true in the research. And so, the symptoms of schizophrenia, basically the main symptoms fall into five different areas and you need two or more of these to qualify.

So, the first one is delusions. So, having fixed false beliefs that aren't consistent with your culture and that other people don't hold is one symptom area. And so, having paranoid delusions where you feel that other people are out to get you or plotting against you, that's a paranoid delusion. Having a grandiose delusion, which is like you feel that you are more important than you really are, like you're a world leader or you have a mission to accomplish, those are delusions. There are also nihilistic delusions, where people feel a part of them is dead or they're all dead. Or some interesting ones that I used to remember is being the X-files delusions where the Capgras delusions, we call them, are where you feel like someone you know has been replaced by someone else. So, those are different types of delusions.

Hallucinations are where you perceive something that other people aren't perceiving. So, hearing voices that aren't there and sometimes you might hear commands to do things, or seeing things that aren't there, those are hallucinations.

Disorganized thought and disorganized behavior. So, in terms of disorganized thought, sometimes people with schizophrenia cannot sort of get from point A to B when they're talking. It kind of weaves all over the place or actually just goes from thought to thought without making sense. Disorganized behavior is generally very poor self care, but in an inability to organize activities. And so, sometimes in the worse cases, sometimes you see people who in the middle of summer are dressed in eight layers of clothing and a winter parka. And that's a disorganization of behavior: an inability to respond to the environment and what is needed. So, those are the first four symptom categories.

The fifth is negative symptoms. And so these include anhedonia, which is a lack of interest or pleasure in things; avolition, which is a lack of motivation; flat affect, so there's not much display of emotion, sadness or happiness; alogia, which is just not a lot of thoughts coming through in their mind. Those are some of the negative symptoms of schizophrenia.

So, we look for these symptoms and, as well, we look for them to occur over a one month period. At least a one month period. And then we look, also, at whether there is at least six months of what we call a prodromal, a deterioration of functioning, so that someone who maybe was going to school and doing quite well suddenly starts to not be able to study, is not taking care of their hygiene, is not sleeping. And that sort of decline is necessary to make the diagnosis as well.

We also have to rule out that this change in behavior and thinking is due to a substance use or is primarily due to substance use because substance use can trigger it as well. Or, that it is primarily due to a medical condition. Many things can mimic schizophrenia, like lupus, like brain tumors. So, we have to rule those things out and do medical tests to rule those things out. And then, we can make the diagnosis.

Sometimes, schizophrenia can be confused with other disorders, like bipolar disorder or depression, so we have to do a careful clinical interview to make sure that this is schizophrenia and not something else.

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