Lecture 2 What is Psychosis

Question 1

What is a psychotic disorder

Answer 1

A severe mental disorder, that causes abnormal thinking and perception

Question 2

How many people are diagnosed with a psychotic disorder

Answer 2

1 in 100

Question 3

What are the positive symptoms of schizophrenia

Answer 3

Hallucinations
Delusions
Disorganised speech
Disorganised or catatonic behaviour

Question 4

What are the negative symptoms of schizophrenia

Answer 4

Flattened mood
Alogia: poverty of speech, speech is effortful
Avolition: flattened level of motivation, you can’t carry out acts of daily life

Question 5

What else do you need as well as positive and negative symptoms of schizophrenia to be diagnosed

Answer 5

There needs to be evidence that the symptoms result in a negative impairment in the individuals ability to go about their lives.

Question 6

What did John & van Os (2001) argue for the distribution of schizophrenia in the general population?

Answer 6

Distribution A: Everyone in the population has symptoms of schizophrenia. PE are distributed continuously and normally, in the same way weight or blood pressure is

Distribution B: PE are distributed bimodally. Majority of the population have very little or no PE and a handful of people that do have loads of PE are the one that will receive the diagnosis of psychosis/schizophrenia

Distribution C: There is a continuous distribution of PE and psychotic traits but at a low level. Majority of people in the population experience low (or zero) symptoms.

Question 7

Further suggestions from John & van OS (2001) -

Answer 7

Assumption that the symptoms of psychosis, like delusions and hallucinations is not inevitably associated with the presence of psychosis. Though the prevalence of the disorder is low in the general population, the prevalence fo the underlying symptoms can be seen to be much higher.

Question 8

What were the findings from Posey & Losch (1983) for the prevalence of hallucinations in college students

Answer 8

71% of 375 college students reported some experience of at least brief, occasional, hallucinated voices during periods of wakefulness. 39% reported hearing their thoughts spoken aloud.

• there was no report of overt psychopathology.

Question 9

What were the findings from Peters and colleagues regarding the PDI (2004)

Answer 9

Using the PDI, with 272 health adults and 20 psychotic inpatients, they found psychotic patients had a higher mean on the PDI, but the range of scores were almost identical between the groups.

Overlapping distributions provide support for the notion of a continuum for psychotic symptoms. You can be perfectly well in your daily life, and still score high on the measures of psychotic traits

Question 10

Findings from Verdoux and colleagues about hallucinations and delusions in a non-clinical sample (1998)

Answer 10

As well as endorsing items on the PDI, 16% of subjects also reported having experienced auditory hallucinations during their lifetime

-subjects had NO history of a psychiatric disorder.

Question 11

What is the Peters Delusional Inventory (PDI)

Answer 11

An inventory that measures attenuated subthreshold, low symptoms of delusional beliefs.
This measure focuses solely on the positive symptoms of psychosis and schizophrenia.

Question 12

What differences between the healthy and deluded group did Peters et al (2004) discover

Answer 12

The groups differed on levels of distress, preoccupation and conviction.
Psychotic individuals find their beliefs very distressing and preoccupying in their daily lives and very believable.

Its not always about WHAT you believe, but HOW MUCH you believe in the thought.

Question 13

Describe the methodology of the NEMESIS study - van Os et al (2000)

Answer 13

Was a study that looked at attenuated psychotic symptoms in the general population.
Multistage, random sampling. They selected random counties, random households, and then a random adult. Administered the CIDI (composite international diagnostic interview)
N= 7076

Question 14

What was the response rate for the NEMESIS study and how did they go about drop outs?

Answer 14

Retention rate was 64%.
They managed to contact 40% of the non-responders, and did a quick health screening to check they are not too different from the actual responders on a number of health categories including MH.

Question 15

Results of NEMESIS study?

Answer 15

17% of the sample experience psychotic like symptoms

4. 2% had psychiatrist rated delusions and hallucinations
5. 1% had a clinical DSM diagnosis

Sig amount of the general population experience sub threshold psychotic symptoms.

Question 16

Results of McGrath et al (2015) and PE in the general population

Answer 16

Same method as the NEMESIS study. N= ~31,200 from 18 countries
About 6% of the sample had experience a PE in their lifetime - this reduced as PEs became more specific (auditory, visual)

They were however, relatively infrequent PE.

Question 17

What did van Os et al (2009) find and conclude about the psychotic continuum in their meta-analysis.

Answer 17

The average prevalence rate was 5% and average incidence rate was 3% for psychosis. This implies that people do not stay ill forever, as if the incidence rate is 3% each month, you’d expect the prevalence rate to go up as well.

People DO get better - and PE might just be transitory rather than persistent. They might just be associated with period of stress in life.

Question 18

What did Kaymaz et al (2012) argue for risk for psychotic disorder

Answer 18

You are 3.5x more likely to convert to full psychotic diagnosis if you have had PE compared to those who haven’t.
Dose-response relationship with severity and persistence of these psychotic experiences

Question 19

Example of person at risk for psychosis - van Os et al (2009)

Answer 19

Model of person C: experienced more adverse childhood experiences - had high sub threshold PE in adolescence and continued to progress and get unwell, never to return to baseline (healthy)

Question 20

What did the Christchurch Health and Development Study in New Zealand find?

Answer 20

Followed up individuals till 30, with an 80% retention rate. They found that the more PE and individual has, the poorer their outcome in life is.

Suggested, rather than waiting for the individual to experience several PE, we should be intervening and targeting areas of their lives that might need help (poor education, poor income, low SES)

Question 21

By how much does EI reduce suicide rates

Answer 21

From 15% to 1%

Question 22

What are considered the approaches to early detection

Answer 22

Large observational studies looking to detect early at-risk individuals, considering family history, birth cohorts and large population studies.

Question 23

How can we use family history for early detection of at-risk individuals

Answer 23

Schizophrenia as a significant heritable component, so we can look at MZ twins to see for a concordance rate for psychosis.
We can also recruit the offspring of mothers who have schizophrenia, and see if their offspring will develop the disorder too

Question 24

Examples of family history early detection studies?

Answer 24

New York High risk study
Copenhagen High risk study
Edinburgh High risk study

Question 25

Issues with family history ED studies?

Answer 25

Ethical? Labelling someone as high risk might actually increase the incidence of PE
Sample size would be very small - recruit individual with schizophrenia (1%of the population) to then only women, and then only those who are pregnant or have a child.
Attrition rates would be high - difficulties bringing child in for check up, hard to maintain their lives and jobs if they’re unwell etc.
How long of a follow up is needed?

Question 26

Methodology of Edinburgh High Risk Study - Johnstone et al (2006)

Answer 26

Began in 1994. Aimed to recruit 200 high risk subjects, aged 16-24 (age range that we know transition usually happens at, so they hoped they didn’t have to follow people for as long to see transition occurring)

Subjects had at least 2 1st/2nd degree relatives with schizophrenia. Recruited via the grandmothers! She got the whole family on board, and made sure they completed all the measures.

Did clinical assessments, neuropsychological and brain imaging

Question 27

Results of Johnstone et al (2006)

Answer 27

14% of the HR individuals developed schizophrenia by 2003 (nearly 10 years later).
Most of the HR individuals however, did experience some level of psychotic symptoms.
Therefore, genetic influence can be seen as a risk for psychotic symptoms, but not a full transition and diagnosis to schizophrenia.

Question 28

How can we use birth cohorts for early detection purposes?

Answer 28

Birth cohorts allow for extensive data to be collected and studied since a wide range of measures have been gathered and analysed.
Researchers can apply to look at the data and analyse anything they deem as important e.g. markers for risk for psychosis.

Question 29

Methodology of the DUNEDIN study - Poulton et al (2000)

Answer 29

Originally began in 1972-1973.
1073 children participated at age 3.
At age 11, used measures to predict diagnosis at age 26, at which point they were assessed for schizophrenia using the DISC-C.
They were given a score 0-2 for each of the items (not present - define)

Question 30

Results from DUNEDIN - Poulton et al (2000)

Answer 30

At age 11, only 13 (1.7%) child scored on 1 of the items (this formed the strong symptom group for early signs of psychosis)

At age 26, 36 (3.7%) of the individuals met criteria for schizophreniorm disorder. A sig minority of the strong symptoms group (25%) had schizophreniform disorder at age 26, compared to only 2% of the control group, and 3.3.% of the sample as a whole.

Question 31

What do the results from the DUNEDIN study suggest

Answer 31

Suggests that some of the sub threshold symptoms and individual experiences at age 11, are good predictors of their outcome at age 26.

Question 32

What did Sipos et al (2004) find in their Sweden population study

Answer 32

Using data from the Swedish medical birth registry, population and housing census’ and inpatient registers, they found a hazard ratio of 10years:1.47 between paternal age and risk for schizophrenia.
They identified a risk factors for paternal age - older the father, the more likely to develop schizophrenia?

Question 33

What did Reichenberg et al (2002) find in the Israeli Draft Registry

Answer 33

Those who later developed schizophrenia, had intellectual, language and functioning impairments.

Question 34

What is a false positive

Answer 34

When you diagnose someone with the disorder, but they do not have it

Question 35

What is a false negative

Answer 35

When you do not diagnose someone with the disorder, but they do actually have it, and hence do not get the help and treatment they need

Question 36

What is sensitivity

Answer 36

The probability that the detection test will be positive in those with the disease

Question 37

What is specificity

Answer 37

The probability that the detection test will be negative in those that do not have the disease - you are correctly identifying the individuals without the disorder you’re looking to detect.

Question 38

What are PPV and NPV

Answer 38

Positive predictive value - the positive test will be a true positive
Negative predictive value - the negative test will be a true negative

Question 39

What are the issues/notes of caution around transition rates?

Answer 39

You always need to consider the timeframe that the study is reporting/studying.
10% transition over 10 years, is very different to 10% over 1 year.
Also, PPV, does not always imply transition in high risk populations. It is harder to get high PPV in the general population, when there prevalence of the desired outcome (the diagnosis of the disorder) is low anyways.

Question 40

What so really good about the DUNEDIN cohort study?

Answer 40

They had astonishing retention rates, where majority of the sample was still kept even after several decades. The people were very keen to take part in follow up studies.
By age 26 follow up, they had about 96% of their sample.