Brief Psychotic Disorder: Sudden onset of psychotic symptoms/disorganized or catatonic
behaviour - emotional turmoil and lasts only a few days -Caused by stress or major
>Criteria: Presence of one/more of: delusions, hallucinations, disorganized speech/behaviour or
catatonic behaviour - The episode lasts anywhere between 1 day and 1 month.
Shared Psychotic Disorder: Delusions that develop in someone who has a very close
relationship with someone who is delusional - the second person comes to believe the
delusions of the first person.
>Criteria: Delusions develop in context of a close relationship with someone who is already
delusional - the delusion is similar to the person who experienced delusional symptoms first.
What causes Schizophrenia? - complex interplay between genetics and the environment
Schizophrenia tends to "run in the family"
strong relationship between being related to someone with schizophrenia and the
higher the percentage that you will develop schizophrenia
Twin Studies: Identical twins have higher rates of schizophrenia than fraternal twins -
Monozygotic twins=28%, Dizygotic twins=6%
>The Genain Quadruplets: All 4 children born with schizophrenia: 1 in 1.5 Billion births
(odds) - Born in the 1930's, Nora, Iris, Myra, and Hester - proves that it could be genetics
but that it could also be environment, thought that because their parents divided them
into two different groups that they became either more sick or less sick - Their parents
thought that Nora and Myra were superior and therefore treated them that way - and
that Iris and Hester were inferior and therefore treated them that way.
89% of people with schizophrenia have no first or second relatives with the disorder
Age-Corrected Incidence Rate: number of new cases that develop - takes into account predicted
breakdowns for subjects who are not yet beyond the age for succumbing to schizophrenia.
-Child with genetic risk of schizophrenia + Dsyfunctional Family = High risk of developing
schizophrenia vs. Child with genetic risk of schizophrenia + Healthy Family Environment= Low
risk of developing schizophrenia.
-Current research is focused on: What is the mode of genetic transmission? and Where are the
genes located? - trying to solve these questions using a complex method called the
"Segregation analysis" - the problem with this is that researchers need to know what they are
looking for and they currently are not sure what they are looking for.
- Currently research is focusing on chromosomes 22,6,8, and 1.
Linkage Analysis: occurrence of a disorder in an extended family is compared with that of a
genetic marker for a physical characteristic or biological process that is known to be located on
a particular chromosome.
Candidate Genes: Genes that are of specific interest to researchers because they are thought
to be involved in a process that are known to be aberrant in a disorder.
-The idea that schizophrenia may be caused by an infection pre-birth ex. Finland 1957, an
influenza that was going around and it was found that if a woman was infected in her second
trimester it was more likely that her baby would develop schizophrenia.
-A mothers immune system may disrupt the development of the fetus's brain. - Rh (Rhesus)
plays a major role in this
-Schizophrenia is more likely to occur after a complicated pregnancy or birth - specifically if
there is lack of oxygen to the baby
-Finally, if a mother is deprived of food during her pregnancy it increases the chances that the
baby will develop schizophrenia
-Schizophrenia is polygenic: ie. involves more than one gene.
Developmental Precursors to Schizophrenia:
-Preschizophrenic children show more:
motor abnormalities - ex. strange hand movements
more negative facial emotion
less positive facial emotion
delayed speech development
low social competence
These differences can be seen by age 2
Endophenotypes: Discrete, measureable traits that are thought to be linked to specific genes
that may be important to schizophrenia