Transcript Module 7.3 Movement Disorders Parkinson’s Disease • A neurological disorder characterized by muscle tremors, rigidity, slow movements and difficulty initiating physical and mental activity • Associated with.

Module 7.3
Movement Disorders
Parkinson’s Disease
• A neurological disorder
characterized by muscle tremors,
rigidity, slow movements and
difficulty initiating physical and
mental activity
• Associated with an impairment in
initiating spontaneous movement
in the absence of stimuli to guide
the action
• Symptoms also include:
– depression
– memory and reasoning deficits
– loss of olfaction
Parkinson’s Disease
• Caused by gradual and progressive death of neurons,
especially in the substantia nigra.
• Substantia nigra sends dopamine-releasing axons to the
caudate nucleus and putamen (of the basal ganglia)
• Loss of dopamine leads to less stimulation of the motor
cortex and slower onset of movements.
Parkinson’s Disease
• The basal ganglia is a group of large subcortical structures
in the forebrain important for initiation of behaviors.
• Comprised of the following structures:
– caudate nucleus
– putamen
– globus pallidus
Parkinson’s Disease: Genetics
• Studies suggest early-onset Parkinson’s has a genetic link.
• Genetic factors are only a small factor to late on-set
Parkinson’s disease (after 50).
Parkinson’s Disease: Risk Factors
• Exposure to certain drugs (MPTP)
• Environmental exposure to toxins, including
herbicides, insecticides, and fungicides
• Head trauma
Parkinson’s Disease
• Cigarette smoking and coffee drinking are
related to a decreased chance of developing
Parkinson’s disease.
Parkinson’s Disease: L-Dopa Treatment
• The drug L-dopa is the primary
treatment for Parkinson’s and is a
precursor to dopamine that easily
crosses the blood-brain barrier.
– Often ineffective and especially
for those in the late stages of the
disease.
• Does not prevent the continued loss
of neurons.
• Enters other brain cells producing
unpleasant side effects.
Parkinson’s Disease: Other Therapies
• Other possible treatments for Parkinson’s include:
– Drugs that stimulate dopamine receptors or block the
breakdown of dopamine
– Neurotrophins (chemicals that support cell growth)
– Drugs that decrease apoptosis (cell death)
– High frequency electrical stimulation of the globus pallidus
– Transplant of neurons from a fetus
– Stem cells: immature cells grown in tissue culture that are
capable of differentiating
Huntington’s Disease
• A neurological disorder
characterized by various
motor, cognitive, and mood
symptoms.
– affects 1 in 10,000 in the
United States
– usually appears between
the ages of 30 and 50.
• Associated with gradual and
extensive brain damage
especially in the caudate
nucleus, putamen, globus
pallidus and the cerebral
cortex.
Huntington’s Disease
• Initial motor symptoms include
arm jerks and facial twitches.
• Motors symptoms progress to
tremors and writhing that affect
the persons walking, speech
and other voluntary
movements.
• Also associated with various
psychological disorders:
– Depression, memory
impairment, anxiety,
hallucinations and
delusions, poor judgment,
alcoholism, drug abuse,
and sexual disorders.
Huntington’s Disease
• Presymptomatic tests can
identify with high accuracy who
will develop the disease.
– Controlled by an autosomal
dominant gene on
chromosome #4.
– The higher the number of
consecutive repeats of the
combination C-A-G, the
more certain and earlier the
person is to develop the
disease.
• No treatment is effective in
controlling the symptoms or
slowing the course of the
disease.
Huntington’s Disease
• A variety of
neurological
diseases are
related to C-A-G
repeats in genes.
• For a variety of
disorders, the
earlier the onset,
the greater the
probability of a
strong genetic
influence.