CASE 8 - schizophrenia Flashcards
what is residual Sz?
used when a person has a previous diagnosis of Sz but no longer has any prominent symptoms of this disorder; the symptoms have generally lessened in intensity. usually includes more -ve symptoms
what is the most common form of Sz?
paranoid. dominated by delusions and hallucinations (+ve symptoms)
what is the main psychoactive substance in cannabis?
delta-9-tetrahydrocannabinol (THC)
what does smoking cannabis lead to?
- decreased BP
- bloodshot eyes
- feeling dizzy
- increased appetite
what are the 2 types of cannabinoid receptors involved in the role of cannabis in psychosis?
CB1 and CB2 receptors
describe CB1 receptors
mediate most effects of cannabinoids on the CNS (also in the lungs, liver and kidneys). these are involved in physiological processes such as appetite, pain-sensation, mood and memory. these receptors are responsible for euphoric and anticonvulsant effects of cannabis
describe CB2 receptors
found in the periphery and are expressed mainly in the immune system and in haematopoietic cells
what are cannabinoid receptors activated by?
> plant cannabinoids (produced by cannabis plant) — THC — through the production of an endocannabinoid (a ligand known as anadamide)
> endocannabinoids (produced by humans)
mode of action of THC
- increases the release of DA in the brain
- this causes stimulation of the D2 DA receptors in the striatum
- this causes an increase in the formation and release of a ligand called anandamide
- anandamide activates cannabinoid receptors
- this leads to euphoria
what does THC disrupt?
coordination and balance by binding to CB1 receptors in the cerebellum and basal ganglia
what are endocannabinoids?
- substances produced in the brain
- used in retrograde signalling between neurones, to temporarily reduce the amount of conventional neurotransmitter released
endocannabinoid production is dependent on what? where are they produced?
- Ca++ dependent
- produced in post-synaptic GABA neurons
mode of action of endocannabinoids — euphoria
- GABA is released into the synaptic cleft and binds to the ‘endocannabinoid source’ (where endocannabinoids are produced)
- this leads to the production of endocannabinoids
- they are released from the depolarised post-synaptic GABA neuron and bind to CB1 receptors in the pre-synaptic GABA neuron and cause a reduction in GABA release
- this causes a decrease in the inhibitory effects in the brain, thus leading to euphoria
aka “endocannabinoid-mediated depolarisation-induced suppression of inhibition”
MoA of endocannabinoids — anticonvulsive
- cannabinoids are thought to have regulatory role in the striatum in terms of glutamatergic signals from the corticostriatal fibres
- intense firing of corticostriatal neurons leads to release of Glu which causes an influx of Ca++ ions in the post-synaptic membrane
- constant Glu release causes Ca++ ions to build up in the post-synaptic membrane
- this accumulation causes Ca++ ions to synthesise endocannabinoids in the medium striatal spiny neurons
- these stimulate CB1 receptors on the pre-synaptic corticostriatal fibres lading to a decreased release of Glu
what appearance of RBCs is suggestive of alcohol abuse?
macrocytic
alcohol and Sz
- over half of people with Sz have a co-morbid drug or alcohol abuse problem
- people with Sz who abuse alcohol experience more frequent relapses of their psychotic symptoms
- dangerous predictor of suicide and violence
- often used as self-medication to help cope with the distressing symptoms or side effects of medications
- increases non-compliance with meds, inability to think clearly, unemployment, depression, worsening hallucinations and delusions
_______ DA release in _______ striatum during acute psychotic episodes — positively correlated with ______ symptoms — correlated with ______ treatment response to antipsychotic drugs
inadequate DA in _______ — associated with deficits in cognitive function and working memory
decreased DA in _______ striatum — negative symptoms
excessive DA release in associative striatum during acute psychotic episodes — positively correlated with positive symptoms — correlated with good treatment response to antipsychotic drugs
inadequate DA in frotnal cortex — associated with deficits in cognitive function and working memory
decreased DA in ventral striatum — negative symptoms
what are some organic causes of psychosis?
- temporal lobe epilepsy
- space occupying lesion (MS)
- limbic encephalitis
- B12 deficiency
- hyperthyroidism
- HIV infection
- dementia
- hypoglycaemia
CBT for psychosis
CBT works by helping you examine how you think about a situation, how you act based on your thoughts, and how your thinking and behavior together affect how you feel. If your thoughts and actions are making you feel bad — or making it difficult for you to function — the goal of therapy is to change them and thus alieviate distress and dysfunction.
In the case of CBTp, the therapist’s goal is not to get the patient to question the reality of delusions or hallucinations, but to reduce the damage they can do.
dosage of antipsychotics
2mg a day (can be divided into 2 doses)
reduce to 0.5mg if over 65 yo, taken twice a day, due to worse renal function
START SLOW AND LOW
section 2 can only be used if the patient has a confirmed mental health disorder
reduced DA function in the prefrontal cortex is associated with which schizophrenia symptoms?
- apathy
- auditory hallucinations
- impaired working memory
- bizarre delusions
- all of the above
impaired working memory
what is the risk of Sz in a person with a first degree relative with the disorder?
- 0.5%
- 1%
- 5%
- 10%
- 50%
10%
which of the following drugs is a second-generation antipsychotic commonly used to treat Sz?
- chlorpromazine
- risperidone
- loxapine
- haloperidol
- clozapine
risperidone
section 2 of the MHA requires an AMHP, and 2 doctors, one of which must be approved by what section?
section 12 approved
early intervention services are designed to provide treatment and support for who?
young people experiencing a first episode of psychosis
what is wavy flexibility a form of?
catatonia
what project from the VTA?
mesolimbic and mesocortical pathways
what pathway is responsible for cognitive control, motivation and emotional response?
mesocortical pathway
which pathway is responsible for the -ve symptoms of Sz?
mesocortical
where are atypical antipsychotics also antagonists?
5HT2A
typical APs have a higher risk of what side effect?
neurological
which AP is used in treatment resistant Sz?
clozapine
