Download Dopamine File

Dopamine
Links to Parkinson’s disease,
Schizophrenia and narcotics
Dopamine
• Dopamine is a neurotransmitter in its own right as
well as being a precursor for adrenaline and
noradrenaline. Low levels of dopamine are associated
with Parkinson’s disease, which is characterised by
tremor and uncontrolled movements. It is treated
with L-dopa (laevodopa), which is a precursor for
dopamine. In contrast, high levels of dopamine are
linked to schizophrenia, increased arousal, reduced
inhibition and increased creativity.
• Q Suggest why treatment with L-dopa might reduce
tremor in Parkinson’s disease patients.
• As with any neurotransmitter, there must be
receptors for it to bind to. There are five
different dopamine receptors, identified as
DRD1 through to DRD5 (dopamine receptor D1
to D5). One of them, DRD4 has many variants
and some of these are linked to specific
conditions such as:
• ADHD or attention deficit hyperactivity
disorder
• addictive/risk-taking activity
• schizophrenia
Dopamine and Parkinson’s
• Among other areas Dopamine works in
the brain’s movement and motor system.
• If this level of dopamine decreases
below the “normal range” we begin to
experience more motor and grossmovement problems.
• Very low levels of Dopamine in the
motor areas of the brain are known to
produce Parkinson’s Disease.
Symptoms of Parkinson’s
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Muscle rigidity, aches and stiffness
Stooped/unstable posture
Loss of balance and coordination
Gait (walking pattern) disturbance
Slow movements and difficulty with voluntary
movements
Small-step gait/walking
Tremors and shaking
Fixed, mask-like facial expression
Slow, monotone speech
Impairment of fine-motor skills
Falling when walking
Impairment in cognitive/intellectual ability
Basically, fewer or
weakened/ damaged
neurones release less
dopamine leading to
fewer action
potentials in the vast
number of neurones
reliant upon this
neurotransmitter
Other examples of dopamine agonists include: Requip, Permax
Dopamine and ADHD
• Dopamine in the thinking areas of the brain
could be considered the neurotransmitter
of focus and attending
• Low levels impair our ability to focus on our
environment or to “lock on” to tasks,
activities, or conversations
• Low levels of Dopamine make concentration
and focus very difficult with low levels also
associated with Attention-Deficit
Hyperactivity Disorder (ADHD)
TREATMENT: Attention deficit hyperactivity
disorder
• ADHD patients have lower levels of dopamine
receptors and transporters in the regions of the
brain that are responsible for motivation and reward.
• It seems strange to treat people with hyperactivity
with a stimulant, but this is exactly what happens.
• ADHD is treated with the stimulant Ritalin
(methylphenidate) which increases the amount of
dopamine in the brain as it compensates for the
deficient reward system and suppresses the
background firing of neurones, so decreasing the
effect of distracters.
• If Dopamine levels in the brain begin to raise,
we become excited/energized, then suspicious
and paranoid, then finally hyper-stimulated by
our environment.
Can you guess which drug/s
• With low levels of Dopamine, we can’t focus
stimulate
dopamine
production?
while with high
levels of Dopamine
our focus
becomes narrowed and intense to the point of
focusing on everything in our environment as
though it were directly related to our
situation.
You can clearly see the comparatively low level of activity
due to low dopamine levels
Drugs and the brain
• High levels of Dopamine are found in
Schizophrenia, drug intoxication, and other
psychotic conditions where the ability to
distinguish the inner world from the real
world is impaired.
• Nicotine (relatively low levels stimulated)
• Cocaine
• Speed (amphetamines)
Treatment
• Dopamine blockers (e.g. Domperidone) are
used
• They bind to the dopamine receptors on
the post synaptic membrane preventing
dopamine binding
• This prevents an action potential
The third row shows the
same addict’s brain after
100 days without any
cocaine. We can see a
little more yellow, so there
is some improvement more brain activity - at
this point. But the addict’s
brain is still not back to a
normal level of
functioning... more than 3
months later. Scientists
are concerned that there
may
areasrow
in the
brain
Thebe
middle
shows
a cocaine addict’s brain after 10 days
In never
this
image,
the level
of brain
function
isto
indicated
in
that
fully
recover
This
PET
scan
shows
us
that
once
addicted
a
drug
like
without any cocaine use at all. What is happening here?
yellow.
The
top
rowisshows
a normal-functioning
brain
from
drug
abuse
and
cocaine,
the
brain
affected
for
a
long,
long
time.
In
Less yellow means less normal activity occurring in the
without
drugs.once
Youaddicted,
can see a the
lot of
brain
activity.changed.
In other
addiction.
other
words,
brain
is
literally
brain - even after the cocaine abuser has abstained from
words, there is a lot of yellow color.
the drug for 10 days.
Speed at work
• One man (In USA) who was a
construction worked took ‘street’ speed
to increase his productivity/ keep awake
etc.
• His levels of paranoia were so high that
he hallucinated that his foot was
speaking to him
• So he cut it off
“Get him a psyche consult”
• Moderately high Dopamine levels make us onguard, suspicious, and prone to misinterpret
experiences in the environment.
• Known as an “idea of reference” in psychiatry, we
begin thinking unrelated experiences are
suddenly directly related to us. People observed
talking across the street are now talking about
us.
• As Dopamine increases, it can become so intense
that we feel the radio, television, and newspaper
contain secret messages directed at us from
Hollywood or elsewhere.
“He’s a different person”
• It’s as though we are attempting to incorporate/add
everything we witness into our life
• In an attempt to make sense, we may become
extremely religious, paranoid, or feel we are a very
important person (‘Napoleon’ syndrome)
• Our mind speed increases and races in an attempt to
add all we see into our life.
• Planes flying overhead are snapping pictures of us and
motorists talking on cellular phones are calling in a
report on us
• Increased Dopamine also increases the perception of
our senses, as though turning up the volume in all our
senses – hearing, vision, taste, smell, and touch.
Psychological conditions
• Dopamine levels typically change very slowly. Patients
who develop Paranoia and/or Schizophrenia often
experience a gradual increase in Dopamine levels over
several years – also experiencing an increase in the
severity of symptoms over those years
• A typical A-level student may develop a sense of
being on-edge or unusual feelings, gradually becoming
suspicious and feeling alienated, moving into auditory
hallucinations, and finally developing bizarre false
beliefs (delusions) of persecution or exaggerated
self-importance over the next several years.
• Stress can often rapidly increase Dopamine, but it
still rarely happens overnight.