publicado em 24/06/2011 às 18h00:00
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Study investigates the relationship between antipsychotic use and addiction

About 60% of schizophrenic patients during or after treatment, become dependent on drugs such as cocaine and amphetamine

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Schizophrenia, which affects about 1% of the world, characterized by a severe mental breakdown, in which the person has trouble distinguishing real fictitious thoughts such as delusions and hallucinations. According to the World Health Organization (WHO), the disease is among the leading causes of loss of quality of life of people between 15 and 44 years. Marinete Pinheiro Carrera, a professor at the Universidade Estadual do Norte Fluminense Darcy Ribeiro (Uenf), believes there is a relationship between schizophrenia and addiction, and develops, with funds from FAPERJ, a study that seeks to understand it. According to the researcher, the project came from the observation that about 60% of schizophrenic patients during or after treatment, become dependent on drugs such as cocaine and amphetamine. Our preliminary results suggest that prolonged administration of some antipsychotic medications used to treat schizophrenia leads to oversensitisation of dopamine receptors, favoring behavioral sensitization, which is linked to the initiation and persistence of addiction, he says.

Marinete explains that the hypothesis of a link between schizophrenia and drug addiction came to realize that the two processes act on the dopamine system that runs on a different neurotransmitter pathways in the brain. In normal doses, dopamine promotes feelings of pleasure and sense of motivation. But the increase or decrease in its concentration can lead, respectively, to the development of mania and depression. The abuse of drugs increase the concentration of dopamine in the brain. While schizophrenia is associated with an imbalance of this neurotransmitter concentrations in their different ways, continues.

For the researcher, the question would understand if this relationship is linked to the disease itself or the antipsychotic drugs used in treatment, since they also interfere with the dopaminergic system. Pharmacy graduate, with master's and doctorate in the area of ​​drugs applied to the psychobiology from the University of São Paulo (USP), Marinete explains that antipsychotics act as dopamine receptor blockers. However, when used for long periods, the body, to compensate for the blockade, increases the sensitivity of receptors (oversensitisation), who will now have greater ability to bind to dopamine.

This process, once developed, would leave the brain more sensitive to dopamine and is well known that the drugs act to exacerbate the dopaminergic action in the CNS, which leads to behavioral sensitization. This phenomenon, which is characterized by a progressive increase of the effects of the drug when the same dose is administered repeatedly, is linked to the onset and persistence of addiction. So our conclusion is that oversensitisation of dopamine receptors favors the development of behavioral sensitization, which would make a schizophrenic patient in treatment or after treatment, be predisposed to become chemically dependent, if you make use of some drugs explains Marinete.

The objective of the project, according to the researcher, is whether two of antipsychotics used to treat schizophrenia, haloperidol and olanzapine, produce oversensitisation of dopamine receptors. For this, four groups of rats received different doses, high and low, these drugs for 10 days, which represents a long-term treatment. After a period without any treatment, all animals were subjected to a chronic administration with apomorphine. This substance simulates the effects of drugs such as euphoria and restlessness, and acts on the same receptors in the body. It also produces behavioral sensitization, said.

Marinete mind that the analysis was made from observations of locomotor activity and behavior of animals. This means that when rats with abrupt changes in behavior and intense movement, it can be concluded that there was oversensitisation of dopamine receptors and there was development of behavioral sensitization.

Our results show that the administration dose, high and low, haloperidol produced oversensitisation of dopamine receptors, and also observed the development of behavioral sensitization. Already with olanzapine showed no significant results, which shows little or no development of both the receptor and oversensitisation of behavioral sensitization, the researcher says, noting that the work is being conducted with the participation of Flávia Regina Cruz Dias, Training Scholar and Technical Training (TCT), FAPERJ, and with the collaboration of Dr. Robert Carey, the State University of New York (SUNY).

schizophrenia with special care

To Marinete, despite the economic impact of schizophrenia is still poorly understood by society, always surrounded by many taboos and prejudices. The most accepted theory to explain the causes of genetic and environmental factors together. The patient would have genes predisposed to the disease, which would be activated by conditions and experiences of their environment.

Among the most common symptoms are hallucinations, delusions of persecution and conspiracy, delusions, depression and difficulties in social relationships. Schizophrenia is not curable, but with proper care the person can recover and return to live a normal life.

The treatment is done not only by medication and psychotherapy, as well as occupational therapy. It is very important to have awareness of the family that, by absorbing most of the tensions generated by the disease need to know and deal with the patient.

Marinete points out that antipsychotics represent a major advance in the treatment of schizophrenia, reduction in hospital admissions and better integration of psychiatric patients to society. In our study, we seek to condemn any medication. We are only calling attention to the conscious, what should be done with any medication, he concludes.


Source: FAPERJ
   Palavras-chave:   Schizophrenia    Neurology    Mental health    Antipsychotics    Chemical dependency   
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