ANTI – PSYCHOTICS Schizophrenia
How are anti-psychotics classified? ❖ Definition: A mental illness characterized
by dopamine dysregulation.
❖ Classified based on the period when they
were developed & their mechanism of ❖ Presentation: Schizophrenia exhibits a
action. combination of positive & negative
symptoms due to dysregulation in
❖ Classified into typical ( First generation) different dopamine pathways in the
& atypical ( second-generation) brain.
❖ SGAs are preferred as first line due to ❖ Positive symptoms are linked to
their low risk of extra-pyramidal dopamine hyperactivity in the
symptoms & tardive dyskinesia
mesolimbic pathway. This over activity
compared to FGAs. leads to hallucinations, delusions,
disorganized thinking.
❖ Extra-pyramidal symptoms are a group
of acute & subacute movement disorders
❖ Negative symptoms are associated
caused by dopamine inhibition in the
with dopamine hypoactivity in the
basal ganglia. They include: dystonia, mesocortical pathway resulting in social
akathisia, Parkinsonism etc.
withdrawal, lack of motivation etc.
❖ Tardive dyskinesia is a late-onset,
irreversible movement disorder caused
❖ The pathophysiology is complex &
by prolonged dopamine receptor multifactorial. It is not solely a
blockade leading to dopaminergic
dopamine disorder but also involves
receptor hypersensitivity. abnormalities in other neurotransmitters
e.g glutamate & serotonin.
❖ Neuroinflammatory processes, oxidative
stress & genetic predisposition may
disrupt multiple brain networks
silmuntaneously leading to a mix of
positive & negative symptoms.
❖ Acute phase – positive symptoms are
more prominent.
❖ Chronic phase – negative symptoms &
cognitive deficits are more pronounced.
, Pathways of Dopamine dysregulation.
These pathways contribute to both symptoms of
schizophrenia & effects of antipsychotic
treatments.
Mesolimbic pathway
➢ Involved in motivation & emotions.
➢ Hyperactivity by of dopamine in this
pathway leads to Positive symptoms e.g
hallucinations
Mesocortical pathway
➢ Responsible for cognition, decision
making & emotional regulation.
➢ Hypoactivity of dopamine in this
pathway contributes to negative
symptoms e.g. apathy, anhedonia &
cognitive deficits e.g. impaired memory
& attention.
Nigrostriatal pathway *
➢ Involved in movement regulation.
➢ Dopamine blockade by typical
antipsychotics here will cause extra-
pyramidal symptoms.
Tuberoinfandibular pathway *
➢ Regulates the secretion of pituitary
hormones especially prolactin.
➢ Normally, dopamine normally inhibits
prolactin release. Inhibition of dopamine
leads to hyperprolactinaemia causing
galactorrhoea, amenorrhoea &
gynecomastia.
How are anti-psychotics classified? ❖ Definition: A mental illness characterized
by dopamine dysregulation.
❖ Classified based on the period when they
were developed & their mechanism of ❖ Presentation: Schizophrenia exhibits a
action. combination of positive & negative
symptoms due to dysregulation in
❖ Classified into typical ( First generation) different dopamine pathways in the
& atypical ( second-generation) brain.
❖ SGAs are preferred as first line due to ❖ Positive symptoms are linked to
their low risk of extra-pyramidal dopamine hyperactivity in the
symptoms & tardive dyskinesia
mesolimbic pathway. This over activity
compared to FGAs. leads to hallucinations, delusions,
disorganized thinking.
❖ Extra-pyramidal symptoms are a group
of acute & subacute movement disorders
❖ Negative symptoms are associated
caused by dopamine inhibition in the
with dopamine hypoactivity in the
basal ganglia. They include: dystonia, mesocortical pathway resulting in social
akathisia, Parkinsonism etc.
withdrawal, lack of motivation etc.
❖ Tardive dyskinesia is a late-onset,
irreversible movement disorder caused
❖ The pathophysiology is complex &
by prolonged dopamine receptor multifactorial. It is not solely a
blockade leading to dopaminergic
dopamine disorder but also involves
receptor hypersensitivity. abnormalities in other neurotransmitters
e.g glutamate & serotonin.
❖ Neuroinflammatory processes, oxidative
stress & genetic predisposition may
disrupt multiple brain networks
silmuntaneously leading to a mix of
positive & negative symptoms.
❖ Acute phase – positive symptoms are
more prominent.
❖ Chronic phase – negative symptoms &
cognitive deficits are more pronounced.
, Pathways of Dopamine dysregulation.
These pathways contribute to both symptoms of
schizophrenia & effects of antipsychotic
treatments.
Mesolimbic pathway
➢ Involved in motivation & emotions.
➢ Hyperactivity by of dopamine in this
pathway leads to Positive symptoms e.g
hallucinations
Mesocortical pathway
➢ Responsible for cognition, decision
making & emotional regulation.
➢ Hypoactivity of dopamine in this
pathway contributes to negative
symptoms e.g. apathy, anhedonia &
cognitive deficits e.g. impaired memory
& attention.
Nigrostriatal pathway *
➢ Involved in movement regulation.
➢ Dopamine blockade by typical
antipsychotics here will cause extra-
pyramidal symptoms.
Tuberoinfandibular pathway *
➢ Regulates the secretion of pituitary
hormones especially prolactin.
➢ Normally, dopamine normally inhibits
prolactin release. Inhibition of dopamine
leads to hyperprolactinaemia causing
galactorrhoea, amenorrhoea &
gynecomastia.
