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Chapter 8

Drugs and Behaviour - Chapter 8.docx

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Bruce Mc Kay

Drugs and Behaviour - Chapter 8  Mental Illness o Referred to as psychological disorders, characterized by alterations in thinking, mood or behaviour  Associated with significant distress and impaired functioning  Can vary from mild to severe o Second leading cause of human disability and premature death in Canada o Depression occurs in 10-25% of females (twice the rate in men) o In people with mental disorders, substance abuse risk is 2-4x as high as general population  Tobacco and cannabis the two most abused o Risk of schizophrenia in adulthood 6x as high in frequent cannabis users o Two proposed theories  Self medication hypothesis  People choose drug that is effective in combating symptoms of psychosis o Provides negative reinforcement  Primary addiction hypothesis  Neurobiology of psychosis and brain areas involved increase vulnerability to substance abuse  Increased vulnerability may produce increased pleasure o Provides positive reinforcement o Medical model th  Before 19 century, mental illness explained by magic or religious explanations or biophysical explanations  Increasing focus on neurobiological cause had beneficial results  Promoted new treatments, reduced stigma and encouraged investment into further research  Term “mental illness” implies particular model for behavioural disorders or dysfunctions  Medical model  Attacked by psychologists and psychiatrists  Patient appears with a set of symptoms, and on the basis of these symptoms a diagnosis is made as to which disease the patient has o Once disease is known, cause can be determined, and cure can be provided  A set of behavioural symptoms is all we have to define and diagnose the disorder  Do people really have a disease with a physical cause and a potential cure? Or is it similar to being described as “friendly”, “crabby”…etc?  Affects thinking, mood or behaviour  Can be associated with distress and impairment of function  Symptoms vary from mild to severe and may require hospitalization  If chemicals can normalize an individual’s behaviour, natural assumption would be that original problem due to chemical imbalance in the brain o Classification of mental disorders  Human behaviour is variable, and cause of mental disorder is unknown, classification of people with mental illnesses into categories is difficult  Psychotherapeutic drugs  Some division important for understanding the uses  DSM provides criteria for classifying mental disorders into hundreds of specific diagnostic categories o Become standard for mental health professionals  Anxiety is normal, but when they become unrealistic, they can interfere with daily life  Physical symptoms may also be present o Referred to as “anxiety disorders” Brian Kwok 1 Drugs and Behaviour - Chapter 8  Tend to not think of anxiety as a behavioural system, but an internal state that causes the disorders  Linked with many disorders, reason why anti-anxiety drugs are applicable to multiple illnesses  Psychosis  Serious mental disorder involving loss of contact with reality  Major disturbance of normal intellectual and social functioning o Not knowing current date, hearing voices and withdrawal from reality  Individuals exhibit perturbations in mood and emotion secondary to alterations in limbic system function  May be viewed as group of symptoms that can have many possible causes  Organic psychoses o One that has known physical cause  Functional psychoses o No known or obvious physical cause  Schizophrenia – shattered mind, not split personality  Mood disorders  Appearance of depressed or manic symptoms  Have no single cause, several factors o Biochemical imbalance in brain, psychological factors and socioeconomic factors  Important distinction is in the drug treatment of mood disorders o Bipolar – manic and depressive episodes o Major depression – only depressive episodes are reported  Anxiety and panic disorders  Panic attacks o Shortness of breath, dizziness, palpitations or accelerated heart rate, trembling, seating, choking, numbness, fear of dying or fear of going crazy  Cholecystokinin plays fundamental role in panic that can be modelled in animals o Can cause panic attacks  People anxiety disorder are sensitive to CCK  May have higher levels in brain  Anxiety and depression important to development of panic disorder  Many different classifications of panic disorder  Many factors that influence pharmacological management of panic o Different psychotherapeutics can be prescribed  Children of adults with anxiety disorders much greater risk of an anxiety disorder than general population o Genetic factor, effect of parenting practices or both  Assigning a diagnosis based off of experience and observation, two diagnosis can be completely different  Treatment of mental disorders o Before 1950  1917 – physical treatment predominant  Great proportion of patients had general paresis – syphilitic infection of the nervous system  Malaria related fever produced marked improvement  1920s – wealthier patients could afford barbiturates and other depressant  Reduction in psychotherapy would enable people to express thoughts better  1933 – Manfred Sakel induced comas in schizophrenics Brian Kwok 2 Drugs and Behaviour - Chapter 8  1932 – Ladislas von Meduna believed that epileptics could not have schizophrenia and vice versa  1930-1940s – Electroconvulsive Therapy – passing electrical currents through brain to trigger seizures  1980s – ECT used when drugs failed to achieve satisfactory response  Use higher among individuals who had comorbid symptoms of depression  Antipsychotics drugs still first choice for schizophrenia treatment  ECT still widely used with severely depressed patients who do not respond to medication  Controversial treatment o Antipsychotics  Phenothiazines – special properties when used by people with mental illnesses  Chlorpromazine did not by itself induce drowsiness or loss of consciousness, made patients unconcerned about upcoming surgery  Referred to as tranquilizers  Neuroleptic – taking hold of the nervous system  Antipsychotics – reflects ability to reduce psychotic symptoms without producing drowsiness and sedation  Treatment effects and considerations  Increase in sophistication of experimental programs that evaluate effectiveness of various drugs  Phenothiazines far from perfect, but better than placebo treatments  Another method to determine effectiveness is determining the incidence of relapse or symptom recurrence  Since 1950 – many new phenothiazines introduced and several completely new types of antipsychotics drugs discovered o Target positive symptoms  Agitation, aggression, delusions and hallucination o Negative symptoms  Social withdrawal, lack of motivation, impaired cognition  First-generation antipsychotics o Classified b their chemical structure o Dopamine D2 receptor binding affinity  Second-generation antipsychotics o Greater serotonin affinity relative to dopamine D2 receptor affinity o 1990s – atypical anti-psychotic agents (second-generation)  Became available on Canadian Market for treatment o Not without side effects  Using ATA in treating children increasing exponentially, raising concerns of appropriateness  No approved indications for ATA use in children and adolescents in Canada  Mechanism of antipsychotic action  All phenothiazines and other first-generations produce pseudoparinsonism o Exhibit symptoms similar to Parkinson’s  Known to be caused by loss of dopamine neurons o Block other types of receptors as well  Clozapine (second generation) different from other antipsychotics o Produced much less psuedoparkinsonism o Worked when some of the other antipsychotics didn’t o Risk of producing deadly white blood cell production suppression Brian Kwok 3 Drugs and Behaviour - Chapter 8  Risperidone, olanzeine and other second generations referred to as serotonin dopamine antagonists o Reduces positive symptoms of schizophrenia o Improving negative symptoms  Side effects of antipsycho
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