Scizophrenia

Question 1

What is the ICD-10 criteria for diagnosing schizophrenia?

Answer 1

At least 1 of these first-rank symptoms for at least 1month:
- thought echo, thought insertion/withdrawal, thought broadcasting
- delusions of control, influence or passivity, clearly referred to body/limb movements or specific, thoughts, actions or sensations
- auditory hallucinations giving a running commentary/discussing patient between themselves/hallucinatory voices coming from somewhere else in their body
- persistent delusions that are completely impossible

Question 2

What is thought echo?

Answer 2

Hearing your thoughts as an auditory hallucination

Question 3

What is thought insertions or withdrawal?

Answer 3

An external force either places or removed your own thoughts from your head

Question 4

What is thought broadcasting?

Answer 4

The experience that your thoughts are no longer private and can be read/heard by other people

Question 5

What is the secondar ICD-10 diagnostic criteria if patient does have a first-rank symptom?

Answer 5

At least 2 second-rank symptoms …
- persistent hallucinations in any modality
- thought disorder (incoherent speech due to breaks in flow and/or making up words)
- catatonic behaviour (posturing, waxy flexibility, mutism, stupor, catatonic excitement)
- negative symptoms not due to depression or medications

Question 6

What are the 4 dopamine projection pathways in the brain?

Answer 6

1. Nigrostriatal
2. Mesolimbic
3. Mesocortical
4. Tuberoinfundibular

Question 7

What are the main dopamine pathways affected in the pathophysiology of schizophrenia?

Answer 7

Nigrostriatal = excess dopamine in associative striatum = positive symptoms/psychosis
Tuberoinfundibular = decreased dopamine =

Question 8

Where does the nigrostriatal pathway project from/to?

Answer 8

From Substantia Nigra pars compacta (SNc)
To the striatum (putamen and caudate)

Question 9

Where does the mesolimbic pathway project from/to?

Answer 9

From ventral tegmental area (VTA)
to limbic (ventral) striatum (associated with reward, motivation, mood, memory…)

Question 10

Where does the mesocortical pathway project from/to?

Answer 10

From VTA
To frontal cortex (specifically the DLPFC, important for cognitive function, emotion etc)

Question 11

Where does the Tuberoinfundibular pathway project from/to?

Answer 11

From tuberal region
To median eminence (infundibular region at top of pituitary stalk)

Question 12

What are the 3 functional subdivisions of the striatum?

Answer 12

Sensorimotor (dorsal) striatum
Associative (mid) striatum
Limbic (ventral) striatum

Question 13

What is the function of the sensorimotor (dorsal) striatum?

Answer 13

Involuntary motor control

Question 14

What is the function of the associative (mid) striatum?

Answer 14

Learning
Habituation
Memory
Attention
Motivation
Emotion
Volition

Question 15

What is the function of the limbic (ventral) striatum?

Answer 15

Rewards system of the Brian

Question 16

What are the 2 divisions of the nigrostriatal pathway?

Answer 16

1. SNc to sensorimotor (dorsal) striatum
2. SNc to associative (mid) striatum

Question 17

What are the 2 dopamine receptor families called ?

Answer 17

1. Dopamine 1 receptor family (D1, D5)
2. Dopamine 2 receptor family (D2, D3, D4)

Question 18

Where are D1 receptors found?

Answer 18

• motor striatum
• associative striatum
• limbic striatum
• cerebral cortex

Question 19

Where are D2 receptors found?

Answer 19

• motor striatum
• associative striatum
• limbic striatum

Question 20

Which dopamine pathways are most effected in schizophrenia?

Answer 20

Nigrostriatal pathway (increased dopamine)
Mesolimbic pathway (normal/slight decreased dopamine)

Question 21

Which change in dopamine levels correlated with negative symptoms?

Answer 21

Decreased dopamine in ventral striatum = Mesolimbic pathway

Question 22

What change in dopamine levels correlated with positive symptoms?

Answer 22

Increased dopamine in associative striatum = Nigrostriatal pathway

Question 23

What is the effect of antipsychotics (D2 antagonists) on
A) positive symptoms?
B) negative symptoms?

Answer 23

A) antipsychotics improve positive symptoms
B) antipsychotics worsen negative symptoms

Question 24

Name a type of glutamate receptor?

Answer 24

NMDA receptors

Question 25

Is the glutamate system hyperactive or hypoactive in schizophrenia?

Answer 25

Hypoactive

Question 26

What is the action of glutamate in a normal dopamine system within the striatum?

Answer 26

Glutamate in the striatum stimulates dopamine synthesis and release

Question 27

What causes the increased dopamine in the associative striatum in schizophrenia?

Answer 27

Hypofunctional NMDA receptors found one GABAergic neurones

• less GABA neurone stimulation = less release of GABA
• GABA usually inhibits glutamate release in the striatum
• less GABA = less inhibition of glutamate release
• glutamate increases dopamine release in the associative striatum

= more dopamine release in associative striatum

Question 28

What causes the decreased dopamine in ventral striatum in schizophrenia ?

Answer 28

There’s a GABA interneurone between the glutamate neurone and VTA

• hypofunctional NMDA receptor = less GABA release
• less GABA release = increased glutamate release onto midbrain GABA interneuron
• more stimulation of the GABA interneurone causes greater release of GABA onto dopamine cell bodies in VTA

= inhibitions of dopaminergic neurones cause decrease in dopamine release in mesolimbic/mesocortical pathways = decreased dopamine in ventral striatum