- Created by: AnnieB
- Created on: 26-05-15 15:47
Antipsychotics (also called narcoleptics) are a group of psychoactive drugs (altering brain function & resulting in changes to perception and behavior) commonly used to treat schizophrenia and other psychotic disorders
There are two main types of antipsychotics:
- Typical antipsychotics - the first generation of antipsychotics (developed during the 1950’s)
- Atypical antipsychotics - a newer generation of antipsychotics (developed during the 1990’s)
People with the symptoms of schizophrenia have problems with seeing things, hearing voices etc. The main theory is the so-called "Dopamine (D2 Receptor Hypersensitivity) Hypothesis".
We know that dopamine (neuro-chemical) is involved with "perception" i.e. seeing, hearing, emotions etc.
If you give a person a drug that increases the activity of dopamine, it can produce the symptoms of psychosis. For example, Amphetamines and L-Dopa (Levodopa: used to treat Parkinson's Disease) can both produce schizoform symptoms
If you reduce the activity of dopamine, it reduces the symptoms of psychosis (eg. using Haloperidol)
Research suggests people with schizophrenia have been shown to have more dopamine activity (or sensitivity) in their brains
Thus, if a person has too much dopamine activity in one part of the brain, this will produce too much "perception". For example, seeing and hearing things that aren't there (and thus thinking they come from somewhere e.g. television, radio etc)
‘Normal’ Dopamine Synaptic Event
‘Excessive’ Dopamine Synaptic Event
Antipsychotics like Haloperidol block dopamine receptors
Typical antipsychotic side effects
Antipsychotics block dopamine receptors (by fitting into the receptor space usually reserved for dopamine).
If a drug blocks all dopamine receptors it can upset muscle control (Parkinson's type symptoms).
If you block acetylcholine receptors, it reduces your learning, produces mild sedation and confusion etc.
If you block noradrenalin it sometimes upsets your blood pressure e.g. you feel dizzy when you stand up etc.
If you block some serotonin receptors, it may have an effect on your appetite and hence weight gain can occur.
The atypical antipsychotics (also known as second generation antipsychotics) are a group of unrelated antipsychotic drugs used to treat psychiatric conditions. Atypicals such as Clozapine work differently from typicals in that they only attach to the specific D2 dopamine receptors (with a transient blocking action on excessive perceptionisation).
Atypicals are preferred to conventional antipsychotics because they produce less side effects, eg. tardive dyskinesia*
Good for ‘positive’ symptoms, however comparative effects on ‘negative’ schizophrenia are marginal (Leucht et al, 1999).
*Involuntary movement of lips & tongue; incidence as side effect of conventional antipsychotics is 30% and irreversible in 75% of these cases (Hill, 1986)
ElectroConvulsive Therapy is not considered a first line treatment but may be prescribed in cases where other treatments have failed. It is only measurably effective where symptoms of catatonia are present and in terms of treatment for drug-resistant catatonic schizophrenia, National Institute of Clinical Excellence recommends its use in the UK.
It is not otherwise recommended as a treatment for schizophrenia
ECT works by using an electrical shock to cause a seizure (a short period of irregular brain activity). This seizure releases a ‘rush’ of chemical neurotransmitters and temporarily alters function (eg. perception/memory etc)
ECT is given up to 3 or 4 times a week and usually for a maximum of 12 treatments.
Before each treatment, an intravenous line is attached and through it the patient will be given an anaesthetic (to induce sleep) and a muscle relaxant. Then an electrical shock is applied to the patient’s head (via electrodes). The shock will last only 1 or 2 seconds (high voltage / low amperage) and will make the brain have a seizure. This seizure is controlled by the medicines to stop/reduce the body having a grand muscular spasm.
The somewhat dazed patient will then wake up within 5 to 10 minutes after the treatment.
ECT side effects
Common side effects include temporary short-term memory loss, confusion, paranoia, nausea, muscle aches and headache.
Some people may have longer-lasting/permanent problems with memory/paranoia.
Nowadays, rare cases result in death. (In the past it was often caused by poor calibration of the shock, coupled with a lack of muscle relaxants)