Schizophrenia Flashcards
How long do SCZ symptoms need to last for?
2 symptoms for 6 months.
Positive Symptoms
- Delusions: beliefs not based on reality.
- Hallucinations (ex: auditory, tactile).
- Speech & behaviour disorganization.
Negative Symptoms
- Flat affect: lack of expressed emotion.
- Avolition: lack off initiative & motivation.
- Alogia: reduced speech.
- Anhedonia.
- Social withdrawal.
Cognitive Symptoms
Impaired working memory, executive functioning, & attention.
how do amphetamines influence SCZ?
greater DA release in SCZ = exaggerates existing psychosis.
DA Imbalance Hypothesis
Suggests that SCZ symptoms are due to reduced DA function in mesocortical neurons & excess DA function in mesolimbic neurons.
Mesocortical Path
- Underactive DA.
- Involved with negative symptoms.
- Higher level cognitive deficits.
Mesolimbic Path
- Overactive DA.
- Involved with positive symptoms, ex: abnormal salience to stimuli (thinking normal stimuli has some special meaning).
Decreased glutamate signaling
- produce low DA release in PFC –> intensifying negative & cognitive symptoms.
- fails to inhibit mesolimbic firing –> leading to excess DA release in NACc & produces positive symptoms.
PCP/Ketamine models
Blocking NMDA receptor with PCP/ketamine leads to increased DA mesolimbic release → mimics positive, negative SCZ symptoms, & cognitive deficits.
Neuroleptics routes of administration
- Aka Antipsychotics.
- Daily oral administration.
- Injections once a month.
Therapeutic efficacy
of Neuroleptics
- Most linked to blockade of D2 receptors.
- Higher concentration of D2 to bind = requires higher dose to be effective.
1st generation antipsychotics examples
chlorpromazine &haloperidol.
Side Effects of 1st Gen Antipsychotics
- Extrapyramidal symptoms
- Parkinsonian syndrome
- Tardive dyskinesia
- Hormone dysregulation
- Neuroleptic malignant syndrome
Extrapyramidal symptoms
drug-induced movement disorders.
Parkinsonian syndrome
symptoms resemble parkinson’s disease.
Tardive dyskinesia
stereotyped involuntary movements, particularly of the face and jaw.
Hormone dysregulation
Breast enlargement & tenderness, decreased sex drive, lack of menstruation, increase release of prolactin, inhibition of growth hormones.
Neuroleptic malignant syndrome
Characterized by fever, rigidity, altered consciousness, & ANS instability (rapid heart rate& fluctuation in blood pressure).
Neurotransmitters involved in Parkinsonian Symptoms
- ) Degeneration of DA cells causes cholinergic neuron to fire less, causing the movement disorder.
- ) Blocking DA receptors in striatum leads to cell degeneration.
- ) ACHe inhibitors block receptors & reduce parkinson’s symptoms.
Abuse potential of 1st Gen Drugs
- Little tolerance, takes weeks to build up.
- Lack of physical dependence (no withdrawal symptoms).
- High therapeutic index → overdose is rare.
- No reinforcement → effects are unpleasant.
Atypical Antipsychotics
2nd generation.
- Include selective D2 receptors antagonists & broad-spectrum antipsychotics.
- Recent findings encourage use of older first-generation drugs = effective at lower cost.
Selective D2 receptor antagonists
Bind to D2 receptors.
- Mild sedation.
- Hormonal side effects.
Broad-Spectrum antipsychotics
Clozapine → high affinity for D4, 5-HT, NE, & ACh.
- Increases release of ACh & DA.
- Addresses positive, negative & cognitive effects.
- Can cause weight gain.
