Introduction to Clinical Neuroscience Flashcards
Schizophrenia
Breakdown of effective integration of emotion, thought, and action
- Delusions, hallucinations, odd behaviour, incoherent thought, inappropriate effect
Schizophrenia as a diagnosis
- Diverse disorder, multiple types with varied profiles
- Have to meet a set of criteria, not a set thing, fuzzy search
Positive symptoms
Experience MORE than what is actually there
e.g. Hallucination, delusion
Negative Symptoms
Absence of experiences
e.g. Blunted emotion, reduced emotional processing, facial affect
Causal Factors - Schizophrenia
- Evidence for a genetic contribution (inherit increased risk)
- Multiple cases
- Infections, autoimmune disorders, toxins, traumatic injury stress
- Interference with normal development of susceptible individuals
Chlorpromazine
Calms many agitated schizophrenics and activates many emotionally blunt schizophrenics
“levelling effect”
Reserpine
Also found to be effective for treating schizophrenia, no longer used
Antipsychotic drugs –> Use/Side effects
- Both drugs are not effective for 2-3 weeks
- Parkinson-like motor effects
Dopamine Theory of Schizophrenia
- Link between dopamine and parkinson’s disease established
- Antipsychotics side-effects suggest role for dopamine-drugs work by decreasing dopamine levels
- Schizophrenia associated with dopamine overactivity
Reserpine - How does it work
Depletes brain of dopamine and other monoamines by making vesicles leak
Amphetamine and cocaine
Dopamine agonists and produce psychosis
Chlorpromazine
Antagonizes dopamine activity by binding and blocking dopamine receptors
Higher the affinity a drug has for dopamine receptors…
The more effective it is in treating schizophrenia
Haloperidol - The exception
How does Chlorpromazine work?
- Chlorpromazine binds to postsynaptic dopamine receptors; it does not activate them, blocks ability of dopamine to activate them
- Blockage of dopamine receptors by chlorpromazine sends a feedback signal to the presynaptic neuron, which increases the release of dopamine
- The feedback signal increases the release of dopamine, broken down into the synapse, resulting in elevated levels of dopamine metabolites
Limitations of Dopamine Theory
- Clozapine, an atypical and effective neuroleptic, acts at D1, D4, and serotonin receptors, but has only some binding to D2 receptor
- Neuroleptics acct quickly at synapse, but do not alleviate symptoms for weeks
- Schizophrenia associated with brain damage: little damage to dopamine circuitry
- Neuroleptics only effective for some
Depression
Normal reaction to loss
Abnormal when it persists/has no cause
Mania
Overconfidence, impulsivity, distractibility, and high energy
Affective disorders
- Psychiatric disorders characterized by disturbances of mood or emotion
- Also known as mood disorders
- Includes depression and mania
affective disorders - Prevalence
Very common
5% suffer from unipolar, 1% for bipolar
Affective Disorders - Genetics
Concordance rate higher for bipolar than unipolar
Antidepressant drugs
Monoamine Oxidase Inhibitors
Tricyclic Antidepressants
Monoamine Oxidase Inhibitors
○ Eg. Iproniazid
○ Prevents breakdown of monoamines ○ (E.g. dopamine, serotonin)
Tricyclic Antidepressants
○ Eg. Imipramine
○ Block reuptake of serotonin and norepinephrine ○ Safer than MAQIs
Selective Monoamine reuptake Inhibitors
- Include Prozac, Paxil, Zoloft, and others
- No more effective than tricyclics, but side effects are few and they are effective at treating other disorders
- Selective Norepinephrine-reuptake inhibitors (SNRIs) are also effective
- Not necessarily getting more effective, but more specific –> less side effects
Diathesis-Stress Model of Depression
- Diathesis = genetic susceptibility
- Diathesis + Stress = depression
- Support is indirect: depressed people…
○ Tend to release more stress hormones
○ Fail dexamethasone suppression test - normal negative feedback on stress hormones not functioning in many depressed patients
Treatment of Depression with Brain stimulation
- Chronic stimulation near the anterior cingulate gyrus helped relieve depression on treatment-resistant patients
Explain how Serotonin works in terms of Depression, How SNRI’s effect this
Serotonin is deactivated in the synapse by reuptake into the presynaptic neuron, causing symptoms of depression
SNRI’s: Block reuptake of serotonin, increasing activation of serotonin receptors
