What exactly happens in the brain?
In: Biology
1. Firstly Schizophrenia probably refers to a number of neurologically distinct diseases which we group together under the term Schizophrenia. This is because diagnostic methods aren’t that sophisticated and we have a narrow range of treatments.
2. How it starts and develops is highly varied. There used to be a misconception that the person’s parents played a major role in causing it, which is not the case. People are at higher risk if they:
(A) Have a family history of Schizophrenia
Are a second generation immigrant
up in a household with a lot of overt conflict
Had a complicated delivery at birth
If their mother suffered certain viral illnesses when pregnant
(B) The most recent evidence suggests that smoking cannabis can cause (as opposed to merely correlating with) people with a predisposition to Schizophrenia to develop symptoms :
https://www.ncbi.nlm.nih.gov/pubmed?term=29557758
Some people thought that people were smoking cannabis *because* they were already hearing voices, in order to calm themselves down, but this appears to be an insufficient explanation.
(C) For males, symptoms will almost always have started to manifest by their mid twenties. For females that threshold is in their early thirties. We don’t really know if there is any “trigger event” which reliably pushes people over the edge, but any stressful event, medical illness or drug taking could potentially do so.
3. Sometimes the first indication is the person becoming more socially withdrawn and demotivated. This is referred to as ‘negative symptoms’. For others, ‘positive symptoms’ such as hallucinations and/or delusions will be the first indication of Schizophrenia. In the textbook pattern of emergence, which doesn’t always match real life, negative symptoms arise early (eg in late teens), and are followed after 1-3 years by the development of positive symptoms.
4. (A) Hallucinations are extremely common. This is where at least one of the five senses is being triggered, but with “No Apparent Stimulus.” By far the most common in schizophrenia are auditory hallucinations (ie hearing voices). Other kinds of hallucinations (eg seeing pink elephants, feeling things crawling under your skin) usually suggest a different diagnosis.
(B) Delusions (beliefs which are provably false, and which do not change despite contrary evidence) are also extremely common. The specific beliefs vary, but often have a paranoid flavour (eg “someone put a microchip in my brain”).
(C) Other features can arise, less commonly than the above, such as:
Disorganised behaviour/thought. Where the person behaves or speaks erratically, with no logical sequence from one act to another, or where they speak unintelligbly, jumping between unrelated subjects. It usually occurs at a later stage of illness, and tends to suggest more severe version of the disease.
Catatonic behaviour. This is a rare feature.
5. None of the above is by itself diagnostic of Schizophrenia. It could be Bipolar Disorder, severe Depression, a different kind of psychotic disorder, or the results of drug intoxication. The person needs to be assesed by a Psychiatrist and it can take months of gathering information and observing the person to be sure that they have Schizophrenia.
6. The events in the brain vary (see point 1 re Schizophrenia as an umbrella term for different diseases). Important to say, there is no definitive explanation for what happens in the Schizophrenic brain. Fundamentally however, Dopamine pathways are thought to be altered. The drugs that treat Schizophrenia target these pathways.
Dopamine is important in how our brain forms models of the external world. Many people have heard of its role in the feeling of “reward”. But Dopamine doesn’t just come in after a pleasurable event : it is also involved in anticipation. By extension, it plays a part in assigning importance to external stimuli. So sex or nice food is more important than info about the economy, etc. Hence alterations in Dopamine transmission can disrupt how we assign importance; over time, so the theory goes, this can lead to the consolidation of irrational thought patterns.
– For more info I suggest Robert Sapolsky’s YouTube lecture on schizophrenia. Contains some upsetting stories of patients, but is an extremely lucid and compassionate introduction.
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