Understanding Schizophrenia Symptoms
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Questions and Answers

What is the primary role of the thalamus in sensory processing for healthy individuals?

  • To inhibit irrelevant sensory information completely
  • To selectively relay relevant sensory information to the cortex (correct)
  • To amplify all sensory inputs for better perception
  • To create sensory memories for emotional attachment

How does dopamine influence GABA neurons in the context of schizophrenia?

  • Dopamine has no effect on GABA neurons.
  • Dopamine inhibits GABA neurons through dopamine receptors. (correct)
  • Dopamine enhances the filtering functions of GABA neurons.
  • Dopamine directly stimulates GABA production.

What contributes to the dysfunction of the sensory filter in individuals with schizophrenia?

  • Overproduction of acetylcholine from mesolimbic pathways
  • Increased levels of serotonin in the thalamus
  • Hyperactivity of NMDA receptors in the cortex
  • Too little GABA in the thalamus due to NMDA-R hypofunction (correct)

Which of the following best describes the heritability of schizophrenia?

<p>80% of the phenotypic variation is attributed to genetic factors (D)</p> Signup and view all the answers

What is the concordance rate of schizophrenia among monozygotic twins?

<p>48% (B)</p> Signup and view all the answers

Which neurotransmitter hypothesis suggests that dysfunctional glutamate neurotransmission contributes to schizophrenia symptoms?

<p>Glutamate hypothesis (C)</p> Signup and view all the answers

What role does glutamate play in synaptic plasticity relevant to schizophrenia?

<p>Promotes long-term potentiation (LTP) (D)</p> Signup and view all the answers

How do environmental factors influence the development of schizophrenia?

<p>They exacerbate existing genetic predispositions (C)</p> Signup and view all the answers

What is a reason why schizophrenia symptoms commonly manifest during adolescence?

<p>Weakened synapses are eliminated during adolescence (A)</p> Signup and view all the answers

Which brain circuits are implicated in the neurodevelopmental hypothesis of schizophrenia?

<p>Dysfunctional circuits involving both dopamine and glutamate (C)</p> Signup and view all the answers

What percentage is often estimated for the heritability of schizophrenia?

<p>50-80% (B)</p> Signup and view all the answers

What is a common environmental risk factor associated with the onset of schizophrenia?

<p>Malnutrition during pregnancy (B)</p> Signup and view all the answers

In the context of schizophrenia, which factor is linked to epigenetic modifications influencing gene expression?

<p>Drug use, especially cannabis (C)</p> Signup and view all the answers

Which hypothesis proposes that alterations in glutamate signaling contribute to the symptoms of schizophrenia?

<p>Glutamate hypothesis (B)</p> Signup and view all the answers

What is a key characteristic of the dopamine hypothesis concerning the etiology of schizophrenia?

<p>It associates schizophrenia symptoms with overactivity of dopamine pathways. (A)</p> Signup and view all the answers

What type of hallucination is most commonly associated with schizophrenia?

<p>Auditory hallucinations (D)</p> Signup and view all the answers

Which of the following is NOT considered a negative symptom of schizophrenia?

<p>Delusions (C)</p> Signup and view all the answers

Which area of neurotransmitter interaction is central to the neurodevelopmental hypothesis of schizophrenia?

<p>Dopamine and glutamate (B)</p> Signup and view all the answers

Which of these symptoms is categorized as a cognitive symptom of schizophrenia?

<p>Attentional problems (B)</p> Signup and view all the answers

In terms of etiology, how are symptoms of schizophrenia understood in relation to brain circuits?

<p>Different symptoms arise from dysfunctions in different brain circuits. (D)</p> Signup and view all the answers

Which of the following delusions involves the belief that one is being targeted or persecuted?

<p>Paranoid delusion (C)</p> Signup and view all the answers

Flashcards

Schizophrenia Sensory Overload

In schizophrenia, the thalamus's sensory filter function is impaired, allowing excessive sensory input to reach the cortex, leading to sensory overload and psychosis.

Schizophrenia Glutamate Hypothesis

The hypothesis proposes reduced function of NMDA receptors contributes to sensory processing issues and symptoms of schizophrenia. Reduced GABA in the thalamus is a key mechanism.

GABA's Role in Thalamus

GABA in the thalamus acts as a filter, regulating the sensory signals sent to the cortex. Reduced GABA leads to sensory overload in schizophrenia.

Schizophrenia's Heritability

Schizophrenia has a high heritability (80%), meaning genetic factors play a significant role in its development.

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Causes of GABA Reduction

In schizophrenia, excess dopamine from the mesolimbic pathway inhibits GABA neurons. Also, deficient NMDA receptor function reduces the effect of glutamate on GABA cells resulting in less sensory filtering.

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What are the 3 categories of schizophrenia symptoms?

The symptoms of schizophrenia can be categorized into three groups: positive symptoms, negative symptoms, and cognitive symptoms.

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What are positive symptoms?

Positive symptoms are an excess or distortion of normal functions, like hallucinations or delusions. They are "added" to normal behavior.

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What are negative symptoms?

Negative symptoms are a reduction or loss of normal functions, such as blunted affect, alogia, and avolition. They are 'subtracted' from normal behavior

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What are cognitive symptoms?

Cognitive symptoms involve deficits in cognitive abilities, such as attention, memory, and executive function. These are problems with how your brain processes information.

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What is the dopamine hypothesis?

This hypothesis proposes that an over-activity of dopamine in the mesolimbic pathway contributes to the positive symptoms of schizophrenia.

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What is the glutamate hypothesis?

This hypothesis suggests that under-activity of glutamate in the prefrontal cortex and hippocampus may contribute to the negative and cognitive symptoms of schizophrenia.

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What is the neurodevelopmental hypothesis?

This hypothesis posits that schizophrenia results from abnormal brain development during prenatal and postnatal periods, leading to disruptions in brain structure and function.

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What is the integrated DA-GLU hypothesis?

This hypothesis combines both dopamine and glutamate hypotheses, suggesting that both neurotransmitters play a role in schizophrenia, with dopamine contributing to positive symptoms and glutamate to negative and cognitive symptoms.

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Schizophrenia's Genetic Risk

Each risk gene for schizophrenia individually contributes a very small increase in the risk of developing the disorder. Many genes can combine to affect the overall risk.

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Gene-Environment Interaction

Gene-environment interactions in schizophrenia mean that both genetic predispositions and environmental factors contribute to developing the disease.

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Epigenetic Modifications

Epigenetic modifications alter gene expression without changing the DNA sequence itself. These changes can be influenced by environment and contribute to schizophrenia's development.

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Neurodevelopmental Hypothesis

The neurodevelopmental hypothesis suggests that schizophrenia arises from disruptions during brain development, impacting brain circuits and particularly NMDA receptor function.

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NMDA Receptor Function

NMDA receptors are crucial for learning and memory. Their dysfunction in schizophrenia contributes to the 'weak' synapses associated with the disorder.

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Environmental Risk Factors

Environmental factors such as stress, infection, malnutrition, hypoxia, urban living, and trauma can increase the risk of developing schizophrenia, often interacting with genetic predisposition.

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Schizophrenia's Multifactorial Nature

Schizophrenia's development is influenced by a complex interplay of genetic predisposition, environmental factors, and individual personality traits.

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The Thalamic Filter

The thalamus acts as a filter for sensory information. In schizophrenia, dysfunction of the thalamus results in sensory overload, contributing to hallucinations and delusions.

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Study Notes

Schizophrenia

  • Schizophrenia is a complex, multifactorial disorder with malfunctioning brain circuits
  • Symptoms arise from errors in neural networks and a lack of connectivity, triggered by a combination of genes, environmental factors, and personality

Symptoms

  • Symptoms are categorized as positive, negative, and cognitive
  • Positive symptoms: Excess of normal functions; include psychosis (delusions and hallucinations), disorganized speech and behavior, agitation
    • Delusions: Misinterpretations of perceptions or experiences; include paranoid delusions, referential delusions, grandiose delusions, scientific delusions, religious delusions, delusion of being poisoned, sexual delusions, and 'leaky mind'
    • Hallucinations: Sensory experiences in the absence of external stimuli; commonly auditory (e.g., harsh voices) but can be visual, tactile, gustatory, or olfactory
  • Negative symptoms: Reduction in normal functions; include blunted affect (lack of emotional expression), dysfunction of motivation, anhedonia (inability to experience pleasure), asociality
  • Cognitive symptoms: Problems with attention, planning, goal maintenance, problem-solving, and prioritizing

Etiology

  • Dopamine hypothesis: Positive symptoms are due to overactive dopamine neurons in the mesolimbic circuit. Negative and cognitive symptoms are due to hypoactive dopamine neurons in the mesocortical circuit.
    • Key dopamine pathways: nigrostriatal, mesolimbic, mesocortical, tuberoinfundibular
  • Glutamate hypothesis: NMDA receptor hypofunction is implicated, potentially leading to sensory overload from dysfunction of the sensory filter in the thalamus
    • Key glutamate pathways: cortical brainstem projection, corticostriatal pathway, thalamocortical pathways, corticothalamic pathways, corticocortical pathways
    • NMDA antagonists like ketamine can temporarily induce similar symptoms to schizophrenia, suggesting a potential role in the etiology of the disease
  • Integrated dopamine and glutamate hypothesis: The integrated hypothesis suggests dysfunction in both dopamine and glutamate pathways, which are intertwined to cause the range of symptoms observed in schizophrenia
  • Neurodevelopmental hypothesis: Genetic predisposition (underlying genes) plays a role but isn't the sole cause; developmental errors in neuronal development, synaptogenesis, glutamate neurotransmission and LTP, coupled with environmental factors such as stress, infection, and malnutrition during pregnancy/early development or other stressors, during adolescence, and considering personality can result in dysfunctional brain circuits and hypofunction NMDA-R leading to the symptoms of schizophrenia
  • Evidence: difficulties in neuronal development, synaptic formation and elimination, glutamate- and dopamine pathways are strongly interconnected in the brain suggesting both are important, genes implicated in neuronal development, synaptogenesis, glutamate neurotransmission, and LTP
  • Risk Factors: Heritability (80%), combination of risk genes (each gene has very small risk increases), gene-environment interactions, changes in gene expression, and epigenetic modifications are implicated.

Learning Outcomes

  • Students can describe schizophrenia symptoms and categorize them.
  • Students can describe the multifactorial etiology of schizophrenia.
  • Students can calculate heritability.
  • Students can explain the dopamine and glutamate hypotheses.
  • Students can explain the connection between the dopamine and glutamate hypotheses.
  • Students can explain the dysfunctioning of the thalamic filter in schizophrenia.
  • Students can explain the neurodevelopmental hypothesis and the roles of dopamine, glutamate, genetic, and environmental risk factors.
  • Students can explain the mechanism of action of classic antipsychotics and their associated motor side effects.

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Related Documents

Schizophrenia - MPBD 2023 Lecture Notes PDF

Description

This quiz explores the complex disorder of schizophrenia, including its multifactorial origins and the various symptoms categorized as positive, negative, and cognitive. You will learn about the nuances of delusions and hallucinations, as well as the impact of these symptoms on individuals. Test your knowledge about the intricacies of this mental health condition.

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