Lecture 7: Psychosis Flashcards
What is the general prevalence of schizophrenia?
About 1.1% in the population over the age of 18 years.
How is schizophrenia related to age and gender? In how many patients does the disorder follow a chronic course? How does it affect mortality and life expectancy?
Schizophrenia is more prevalent in males and usually onsets in late adolescence, with 75% showing a chronic course. The mortality in schizophrenia is 2.5 times higher than in the general population, mostly due to high suicidality. The life expectancy is 12-15 years shorter than in the general population.
What is the general prognosis 10 years after the initial diagnosis?
25% recover completely, 25% show great improvement, 25% improve but still need extensive support, 15% remain hospitalized and 10% die, mostly because of suicide.
Name some risk factors for developing schizophrenia.
Genes, cannabis use, living in a city, experiencing (social) distress.
What do positive symptoms refer to in schizophrenia? Name and describe them.
Positive symptoms include:
(1) hallucinations (perception without an external stimulus) (2) passivity experiences (e.g. feeling controlled by an external agent)
(3) delusions (fixed false beliefs that do not hold within the cultural context; can be bizarre or non-bizarre)
Name examples for disorganization in schizophrenia.
Thought disorder, derailment (loose associations), poverty of speech, illogicality, perseverations and neologisms.
What do negative symptoms refer to in schizophrenia? Name and describe them (if necessary).
Negative symptoms include:
(1) flat affect
(2) anhedonia (lack of pleasure in everyday life)
(3) lack of ability to begin and sustain planned activities
(4) alogia (speaking little, even when forced to interact)
(5) social withdrawal
Explain a potential cognitive mechanism that might underly hallucinations.
Due to problems in the attribution of internal speech internal voices seem externally generated. This includes distorted bottom-up (impaired awareness of self-generated actions) as well as top-down processes (bias towards external attribution).
What were the findings of the meta-analysis by Waters et al. (2012) regarding self-monitoring in schizophrenia? What were the results comparing patients with auditory hallucinations to patients without auditory hallucinations=
The meta-analysis showed significantly reduced recognition of self-generated events across different paradigms (23 studies, N=1370). Patients with auditory hallucinations performed worse than patients without hallucinations.
Shortly explain the forward prediction model related to perception.
The brain calculates the sensory consequences of an action and attenuates the perception related to this prediction. Concordance between prediction and perception signifies the movement is self-generated, while discrepancies suggest that the movement is externally generated.
What did the study by Shergill et al. (2000) find regarding brain activation when comparing auditory hallucinations with imagining another persons’s voice?
Auditory hallucinations led to similar activation in the inferior frontal, premotor, inferior parietal and temporal cortex. However, there was a reduced activation in the supplementary motor area that is associated with deliberate generation of speech.
What did Hugdahl and Sommer (2018) find when they compared brain activation during auditory hallucinations with listening to external sounds?
The brain activation in both conditions were largely similar. This was also found for visual hallucinations with activation of the visual cortex.
What did Kompus et al. (2010) find when they compared the brain activation of patients with hallucinations while they were either listening or not listening to an external auditory stimulus?
They found increased activation in the absence of an external stimulus and decreased activation in the presence of an external stimulus. These findings could either be explained by a process of sensory-perceptual filtering or an attentional bias towards internal stimuli.
What is the general conclusion regarding auditory hallucinations and prediction models?
Impaired forward prediction leads to increased perceptual impact of self- generated actions, which leads to the impression that these actions were caused by an external agent.
What were the main findings by the study from Dudley et al. (2016) regarding decision making and delusions in patients with psychosis?
According to their meta-analysis require patients with psychosis significantly less information to make decisions in comparison to healthy controls. This jumping-to-conclusion tendency was linked to a greater probability of delusion occurrence in patients.
