10/19 Psychosis - Tobia Flashcards
psychosis
how to approach deciding if someone has psychosis
rule out life threatening causes:
- stat EKG
- vital signs
- consider withdrawal syndromes (esp from alcohol, sedative hypnotics)
then, make sure psychosis isnt caused by an underlying medical condition
which neurotransmitter is implicated in all psychoses
dopamine
Hibernotherapie
compound used by French anesthesiologist who noticed that using it allowed for significantly less anesthesia intraoperatively
- as a result: pts experienced drop in all-cause mortality
psychiatrist friend decided to try on psych patients to reduce agitation
- as a result: pt reported less agitation AND improvement of psychotic sx
FDA approved as clorpromazine
- hits DA receptors in CNS
- first antipsych!
role of dopamine in psychoses
final common pathway for all psychoses
- substance-induced (ex. stimulants)
- resulting from general medical condition
- deliriums
DA neuroanatomy
long tracts
short tracts
long tracts:
- nigrostratal tract
- mesolimbic tract
- mesocortical tract
short tracts:
- tubero-infundibular tract
- retina and adrenal medulla
nigrostriatal tract
fxs
cell bodies/projections
what does DA excess in this tract look like?
- synthesizes most of CNS dopamine
- influences fx of extrapyramidal motor system
- cell bodies found in substantia nigra pars compacta → project to D2 receptors in striatum (caudate and putamen)
dopaminergic excess in nigrostriatal tract
- neurocognitive deficits: speech, memory, attn/conc
- increase in DA in striatum thought to be related to neurocog deficits in schizophrenia
- movement disorders (hyper/brady/akinesis)
common side effect of antipsychotics and why?
Parkinsonism (hypokinetic movement disorders)
- psychosis is resulting from relative or absolute high level of DA in CNS
- antipsychotics reduce DA → drop DA that would hit inhibitory D2 receptors in the indirect pathway (basal ganglia) → overall bradykinetic
mesolimbic tract
cell bodies in VTA of midbrain → project to D4 receptors in limbic system
hyperactivity?
- positive sx of schizophrenia
mesocortical tract
cell bodies in VTA of midbrain → project to frontal cortex, cigulate and prefrontal gyri
hypoactivity via D2 receptor antagonism
- negative sx
- mood and cognition effects
schizophrenia and the DA shunt
conditions like schizophrenia have both positive and negative sx
- potentially explained by thinking of a “dopamine shunt” moving DA from mesocortical tract → mesolimbic tract
- hypoactivity in mesocortical tract → negative sx
- hyperactivity in mesolimbic tract → positive sx
tuberoinfundibular tract
links ___ & ___
function
effect of antipsychotics
TI tract (short pathway)
links hypothalamus → pituitary
- chronic DA secretion → decr prolactin secretion
- therefore…one side effect of medications that lower CNS DA concentration is: HYPERPROLACTINEMIA
common side effects of medications to decrease CNS DA
- reduction of positive sx (mesolimbic)
- aggravation of negative sx (mesocortical)
- hyperprolactinemia (TI tract)
retina DA
believed that excess DA here → visual hallucinations associated with psychosis
psychotic disorders
2 groups, disorders within them
schizophrenia spectrum
- brief psychotic disorder
- schizophreniform disorder
- schizophrenia (schizoaffective disorder)
other psychotic disorders
- delusional disorder
- catatonia
schizophrenia
two or more for a 1-month period
- positive sx
- delusions
- hallucinations
- disorganized speech
- disorganized or catatonic behavior
- negative sx