HD Motor and Treatment - Erickson

Question 1

The direct pathway is hyperactive in what kinds of disorders?

Answer 1

Hyperkinetic disorders’

LIKE - Huntington’s

Question 2

The indirect pathway is hyperactive in what kinds of disorders?

Answer 2

Hypokinetic disorders

LIKE - Parkinson’s

Question 3

What happens in the connections of the basal ganglia to cause motor problems in Huntington’s Disease?

Answer 3

Loss of neurons in caudate/putamen (striatum)
Loss of nigrostrital GABA projections to the substantia nigra pars reticulata

Result: Decreased inhibition of thalamus and cortex will increase

Question 4

How does excess dopamine from the SNc or other sources impact motor?

Answer 4

It will cause increased movements and psyche symptoms

• It stimulates the direct pathway thru d1 receptors
• inhibits the indirect pathway thru d2 receptors

Question 5

So what is the general treatment for chorea accompanying HD?

Answer 5

Dopamine blockers and dopamine depleters

Question 6

What is a typical antipsychotic dopamine blocker?
How does it act?
Risks?

Answer 6

Haloperidol
D2 antagonist
Risk of permanent tarditive dyskinesa
(abnormal movements of mouth and tongue)

Question 7

Name 3 atypical dopamine-blocking antipsychotics:

Answer 7

Olanzapine
Risperidone
Clozaril

Question 8

Name a common dopamine depleter

Answer 8

Tetrabenazine

It is a monoamine depleting agent
Inhibits DA transport into presynaptic vesicles

Question 9

Name 3 medications used to take care of some of the psychiatric symptoms of HD:

Answer 9

Valproic acid - enhances GABA effects

Lithium - influences reuptake of 5HT, NE and postsynaptic D2 receptors

SSRI’s - helpful for anxiety and depression
(keeping anxiety down helps control symptoms)