Ethnicity strongly linked to treatment resistance in schizophrenia

Published on February 6, 2013 at 5:15 PM · 1 Comment

By Lucy Piper, Senior medwireNews Reporter

Patients with schizophrenia are at heightened risk for being resistant to treatment if they are White European, study findings reveal.

"The cause of this association could be mainly cultural," say Vincenzo De Luca and colleagues, from the University of Toronto in Ontario, Canada.

"Most studies involving access to care have shown significant ethnic differences in relation to social factors, which include employment, living situation, family support, or general practitioner involvement," they explain.

"These factors affecting pathways to care have shown to be vital indicators of duration of untreated psychosis."

The team assessed treatment response in 497 patients diagnosed with schizophrenia spectrum disorders. Medication history was obtained from medical health records.

In all, 30% of the patients were classified as treatment resistant according to the American Psychiatric Association criteria, which states that a patient is treatment refractory when they have little or no symptomatic response to multiple (at least two) antipsychotic trials within an adequate duration (at least 6 weeks) and with an adequate dose within the therapeutic range.

When stratified according to ethnicity, 36.7% of White Europeans were resistant to treatment, compared with 19.1% of non-White Europeans. This means that being of White-European ethnicity conveys a 1.78-fold increased risk for treatment resistance, the team reports in Comprehensive Psychiatry.

By contrast, neither gender nor a positive family history for psychiatric disorders were significantly associated with treatment resistance.

Patients who were resistant to treatment had a significantly longer duration of illness than those who were not resistant, at 21 versus 15 years, and there was a significant association between a high number of hospitalizations and non-resistant status.

Treatment-resistant patients were also more likely to be receiving clozapine treatment (odds ratio [OR]=2.9), polypharmacy treatment (OR=2.4), and a combination of clozapine and polypharmacy (OR=3.8).

The researchers comment that previous research has shown that African-American patients with psychotic disorders receive higher doses of antipsychotic medications than White patients, and are more likely to receive depot antipsychotics and less likely to be prescribed second-generation antipsychotics despite no evidence of a difference in clinical severity or a need for higher therapeutic doses.

"There is a possibility that because African-American patients are prescribed higher doses and given depot medications they have a lower chance of developing resistance as compared to white Europeans," they suggest.

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Comments
  1. Stefan Andersson Stefan Andersson Sweden says:

    Can the exposure to stimulus (non-verbal) - stimulus (verbal) contingencies (classical conditioning) when you with a short delay are able to restore a verbal message or interpret what subjectively seems to be a verbal message contribute to a tendency to interpret what people normally ignore?

    To reward a behavior which generates the exposure to stimulus (non-verbal) - stimulus (verbal) contingencies (classical conditioning) like these may have such a profound effect that some people develop a mental illness...

    Quote:””It was believed that dopamine regulated pleasure and reward and that we release it when we obtain something that satisfies us, but in fact the latest scientific evidence shows that this neurotransmitter acts before that, it actually encourages us to act. In other words, dopamine is released in order to achieve something good or to avoid something evil,” explains Mercè Correa.” Source: ScienceDaily , Dopamine Regulates the Motivation to Act, Study Shows

    www.sciencedaily.com/.../130110094415.htm

    Classical conditioning (also referred to as pavlovian or respondent conditioning) can be the result of stimulus (non-verbal) - stimulus (verbal) contingencies like these and may cause the need to access a verbal message in response to non-verbal environmental sounds while operant conditioning is the result of response - stimulus contingencies and what generates our ability to satisfy the need to access a verbal message. In other words to frequently be forced to restore a verbal message due to a hearing loss may cause the need to access a verbal message in response to non-verbal environmental sounds (1) and the need to access what you learn to expect can motivate a behaviour which satisfies the need to access a verbal message (2). (Hearing impairments are, as expected, important risk factors for schizophrenia...)

    1.) Any signal that consistently precedes a meal, such as a clock indicating that it is time for dinner or an appetizer, may cause us to feel hungrier than before the signal because we learn to expect a meal in response to CS (CS will eventually predict the arrival of food) and non-verbal environmental sounds that consistently precedes a verbal illusion (information) can like any signal that consistently precedes a meal become a conditioned reinforcer that can activate a drive representation D.

    2.) Operant or instrumental conditioning is a form of learning in which an individual's behaviour is modified by its consequences and it involves learning to make a response in order to obtain a reward or avoid something unpleasant. What you learn to expect or predict in response to a signal that consistently precedes a reinforcer can motivate an operant behaviour which has been established and fine tuned because it satisfies the need to access what you learn to expect or makes it possible to avoid what you learn to expect.

    People who mostly hear the kind of voices they want to hear may eventually lose their ability to hear these voices because they are able to reveal a verbal illusion (1) while some people who mostly hear the kind of voices they want to avoid learn to sometimes avoid the kind of voices they hear by paying more attention to what they are able to hear objectively (2) ...

    1.) Extinction: The occurrences of a conditioned response will eventually decrease or disappear when a conditioned reinforcer (un-patterned noise) no longer is paired with a primary reinforcer (information)!

    2.) People who consistently avoid the event they fear will continue to expect a fearfull event (phobia) and people who selectively are able to avoid some of the voices they hear by revealing a mismatch will continue to expect to hear the voices they were able to avoid! To continue to expect to hear the voices you are able to avoid by revealing a verbal illusion may eventually generate negative symptoms like poverty of speech, affective flattening and avolition and to continue to expect to hear the voices you are trying to avoid will generate the voices you are trying to avoid whenever you are unable to reveal a verbal illusion. The allocation of processing resources from what generates the ability to consciously control covert speech to what you are able to attend with a corresponding top-down sensory expectation must be greater when you are trying to avoid a voice with a negative emotional content than when you are trying to restore a verbal message or interpret non-verbal environmental or tinnitus like sounds with no connection to a verbal message (not coexisting with or corresponding to a distorted verbal message) and avoidance may therefore also generate a more disorganized behavior.

    "Non-clinical populations usually experience voices with a neutral or even positive emotional content" and to selectively be able to avoid some voices expressed with a negative emotional content may eventually generate a more unpleasant voice hearing experience, disorganization and negative symptoms.

    An already stigmatized experience can be connected to some of what characterize an even more stigmatized illness, but most people who hear auditory hallucinations do not meet the diagnostic criteria for schizophrenia!

    Conditioned avoidance response (CAR) is a test with predictive validity for antipsychotic efficacy, but negative symptoms are very hard to treat and I wonder if this can be explained with the assumtion that negative symptoms predominantly depend on that you previously in avoidance WERE able to reveal a verbal illusion. I other words I wonder if the gesture (and I mean whatever gesture) you are about to produce (covertly or overtly it does not matter) eventually take on the value of what you in avoidance were able to reveal as irrelevant because it determines a top-down sensory expectation which according to previous events consistently generates a mismatch... (I assume, but have not yet been able to verify (!) that the ability to attenuate a response which allows rats to avoid something unpleasent can predict if a medicine have an effect or not because it corresponds to how well the medicine attenuates a condition avoidance response in humans... )

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News-Medical.Net.
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