Download Biological Treatments of SZ

Biological Treatments of SZ
Learning Objectives
Drugs – Atypical & Typical
Learning Objectives
• name the different biological
therapies used to treat schizophrenia
• explain the action of different drugs
used to treat schizophrenia
Background
• There was no effective treatment for Sz prior to the
discovery of dopamine in 1952.
• Drugs were developed that had a direct effect on the
action of the dopamine neurotransmitter.
• Drugs which markedly reduced the symptoms in
people who were severely ill became known as
antipsychotics.
•
Anti-psychotics
• Antipsychotics are given to treat the most disturbing
forms of psychotic illness such as schizophrenia and
bipolar disorder.
• There are two types of antipsychotic drugs:
• 1. Conventional antipsychotics
• 2. Atypical antipsychotics
Conventional Anti-psychotics
• Used primarily to combat the positive
symptoms of Sz such as disordered thinking
which are products of overactive dopamine
systems.
• Their basic mechanism is to reduce the
amount of dopamine and so reduce the
symptoms of Sz.
•
How do they work?
• They work by binding to dopamine receptors
(particularly D2 receptors) and thus blocking their
action, not stimulating them.
• By reducing the stimulation of the dopamine
system in the brain, antipsychotic drugs can
eliminate the hallucinations and
delusions experienced by patients with Sz.
• The effectiveness of these dopamine antagonists
in reducing the symptoms of Sz is what led to the
development of the dopamine hypothesis.
•
Atypical Anti-psychotic drugs
• Developed in the 1990s
• Combat the negative as well as the positive symptoms
of Sz
• As well as acting on the dopamine system they also
stimulate serotonin receptors.
• In the same way as conventional psychotics they also
bind to D2 receptors but rather than permanently
block the dopamine action, they temporarily bind to
the receptors and then rapidly dissociate to allow
normal dopamine transmission.
•
Evaluation – In terms of effectiveness
& appropriateness
• Overall positive implication of antipsychotic
drugs:
• Drug therapy offers more humane & effective
treatments than previously available, EG: ECT
& Psychosurgery
• Rapidly reduce most disturbing symptoms
• Aid individuals in living a more normal life
Effectiveness of conventional antipsychotics
• Davis (1990) – Drugs effective in comparison
to placebo in of those reported on – a
reduction of apprx 30% relapse rates
• Vaughn & Leff (1976) – Found drugs to be
effective in only some cases – (where homelife
was extreme and unsupportive)
• In more supportive home environments, no
significant difference between those on
antopsychotics and placebo
Conventional Antipsychotics
evaluation cont’d
• Some extreme side effects - · Weight gain,
diabetes, sexual dysfunction, insomnia and
muscle tremors
• 30% of patients experience tardive dyskenesia
– uncontrollable movement & shaking of
body, limbs & face
• Such side effects might explain high drop out
rates
Atypical drugs – Evaluation
• Appear to be effective on both positive and negative
symptoms
• Leucht (1999) meta-anlaysis - superiority of the atypical
drugs compared to conventional drugs was only
moderate
• Girgis et al (2011) concluded the newer atypical drugs
are no more effective and cause only slightly fewer side
effects.
• Jetse (1999) found a 30% rate of tardive
dyskenesia in people taking conventional
compared to 5% with atypical antipsychotics
General Evaluation & IDA
• Placebo comparisons raise ethical issues as such
patients will be in a drug withdrawal state which
results in overwhelming flooding of dopamine
system ( See dog book – pg 169 – Ross & Read
2004)
• Drug resistance over time – Drugs don’t work for
all
• Appears to work best in conjunction with support
from home
• Cost benefits – Typical anti-psychotic EG:
Chloromazine - £10 per year
• Atypical anti-psychotic – clozapine - £1500 per
year
After two decades, it
is now clear that
antipsychotic drugs
do not cure
schizophrenia.
No other single therapeutic
procedure can compete with
drug treatment in terms of
rapid effectiveness, sustained
action, general availability and
ease of application.
Relapse rates, in general,
during withdrawal from
psychiatric drugs, are about
10 times higher than would
be expected if the drug had
never been taken.