October 9, 12
PSYCH – Week 5 Online Readings
Week 5: The Nature and Causes of Psychological Disorders
Focus Question: How can the definitions in the DSMIVTR help diagnose and treat
Will Cover: Substance related disorders, schizophrenia and other psychotic disorders, and
A psychoactive substance is a chemical that acts on the central nervous system. It causes
changes to a person’s emotions, perceptions, or thoughts. EX: cocaine, alcohol, nicotine,
and (if used intentionally to get high) substances like paint thinners and gasoline.
Psychoactive substances can lead to a number of substancerelated disorders.
Two categories of substancerelated disorders: substanceuse disorders and substance
1. Substance dependence
Substance dependence occurs when an individual's repeated use results in "tolerance
withdrawal and compulsive drugseeking behaviour".
2. Substance intoxication
Substance intoxication occurs when a person suffers clinically significant negative or
harmful behavioural changes or psychological effects because of the influence of a
2. Substance withdrawal
Substance withdrawal occurs when a person suffers clinically significant negative or
harmful behavioural changes or psychological effects because they recently stopped
prolonged use of a psychoactive substance.
Characteristic symptoms of schizophrenia and schizophrenic disorders October 9, 12
Grossly disorginaized or catatonic behaviour
Disorganized thought and speech
Flattened affect (dampened emotional responding)
Slowing of speech, slowing of movement
o These can be grouped into two categories:
1. Positive symptoms usually reflect an excess or distortion of a normal
2. Negative symptoms reflect a diminution or loss of normal function.
Positive = presence, negative = absence
Schizophrenia has five main subtypes that each feature different symptoms. However, all
subtypes are characterized by the presence of at least two of the following:
• Disorganized speech
• Grossly disorganized or catatonic behaviour
• Negative symptoms (e.g., flattened affect, decrease in production of speech, etc.)
Schizophrenia can be diagnosed on the basis of only one symptom if it is a bizarre
delusion, a hallucination that consists of a running commentary on the person’s
thoughts/behaviour, or a hallucination that involves two or more voices conversing with
If the symptoms of schizophrenia only last from one to six months (i.e., a shorter
duration than is required for a diagnosis of schizophrenia) then it is classified as a
If a person experiences a mood episode (i.e., major depression or mania) at the same
time that he/she is exhibiting symptoms of schizophrenia (e.g., hallucinations, delusions,
etc.), then it is classified as a schizoaffective disorder.
Delusional disorder is marked by delusions that are considered nonbizarre. That is, they
are based on things that could possibly happen – for example, delusions about being
followed or delusions of being significantly more powerful and important than one really
is. (Note: Bizarre delusions are delusions about things that are not possible, for example,
the belief that you are Jesus Christ or that you control another’s thoughts.)
Brief psychotic disorder is an episode of psychotic symptoms that lasts between one day
and one month.
Shared psychotic disorder (also called folie à deux) is the development of a delusion
that is similar to a delusion already held by someone close to the individual. For example,
if a man with schizophrenia has a delusi