DEMENTIAS AND PARKINSONS DISEASE

1
DEMENTIAS AND PARKINSONS DISEASE

• These are neurodegenerative conditions in the
  brain in which there is progressive loss of
  neurons in particular pathways
• Dementia
• any disorder which permanently damages areas
  of the cerebral cortex
• severe intellectual deterioration
• - diagnosis? - depression may appear to be
  dementia

2
DEMENTIA - ALZHEIMERS

• (i) ALZHEIMERS DISEASE
• 50 - 70 of all dementia
• Risk factors family history, ? age, Down
  syndrome, head injury
• Cortical atrophy, loss of neurons in frontal and
  temporal lobes
• Histology - senile plaques of amyloid protein and
  neurofibrillary tangles
• Gene on Chr. 21 for precursor protein

3
DEMENTIA - ALZHEIMERS

• Loss of ACh-releasing neurons projecting from
  lower forebrain ? cortex
• 3 stages of altered function (2-20 years)
• mild loss of memory, personality?
• confusion, disorientation, agitation ?
  incontinent, apathetic
• No pharmacological treatment, only management of
  depression, agitation
• Trials with drugs which ? ACh (AChEIs)

4
DEMENTIA - CVA

• (ii) MULTI-INFARCT DEMENTIA
• 20 of dementia
• Gradual or abrupt (not progressive)
• Due to multiple emboli
• Focal ischemia ? specific symptoms

5
DEMENTIA - ALCOHOLISM

• (iii) WERNICKE-KORSAKOFF SYNDROME
• Due to chronic alcoholism
• Wernickes Disease Vitamin B1 (thiamine)
  deficiency - reversible with diet
• Korsakoff Syndrome not reversible
• (recent memory loss ? confabulation)

6
PARKINSONS DISEASE

• Disorder of basal ganglia ? resting tremor
• 
  rigidity
• 
  slow movement
• Causesidiopathic, may be environmental
  (neurotoxins, viral encephalitis, trauma)
• Dopamine (DA) is? in nigrostriatal pathway (from
  substantia nigra ? striatum in basal
• 
  ganglia)

7
PARKINSONS DISEASE

• Loss of DA neurons (inhibitory) ? n.t. imbalance
  in extrapyramidal motor pathway ? hypokinesia,
  tremor
• ?DA ? ? ACh release ? motor symptoms
• ANS symptoms may occur (? sweat, saliva)
• Dementia in 40 cases

8
PARKINSONS DISEASE

• Treatment
• - Anticholinergic drugs (antimuscarinic) block
  ACh receptors, ? tremor, rigidity
• - DA precursor L-dopa crosses bbb ? ? DA in
  brain
• - L-dopa is ?by peripheral metabolism (GIT
  wall), so dopa decarboxylase inhibitor used
• - DA agonist (apomorphine) can stimulate
  receptors directly in severe cases

9
PARKINSONS DISEASE

• Prolonged treatment ? dyskinesias
• (on-off phenomenon, uncontrollable
  movements)
• Surgical destruction of part of the basal ganglia
  pathway can eliminate abnormal movements
• Transplants of tissue which can release DA?