Dementias and Parkinson's disease

Question 1

Define what is meant by dementia

Answer 1

A progressive and largely irreversible clinical syndrome that is characterised by a widespread impairment of mental function

Question 2

What are the 5 main types of damentia?

Answer 2

1. Alzheimer’s disease
2. Vascular dementia
3. Mixed (AD and VD)
4. Frontotemporal dementia
5. Denmetia with lewy bodies

Question 3

What are the rare forms of dementia?

Answer 3

• Huntington’s disease
• parkinson’s disease

Question 4

What are the risk factors for dementia?

Answer 4

• Age
• Sex (greater if you’re female)
• Genetics
• PMH of vascular disease or traumatic brain injury)
• Social activity (less then > risk)
• mental activity (less then > risk)

Question 5

What is the most common form of dementia and what is the characteristic pathology?

Answer 5

Most common form is alzheimer’s disease

Question 6

Describe the current theory on the cause of Alzheimer’s disease

Answer 6

• Amyloid plaques are composed of a peptide (amyloid beta protein)
• This is a fragment of a much larger protein amyloid precurser protein which is encoded by a gene on chromosome 21
• people with familial AD have specific mutation of these gene
• But some people have AD and have mutations of genes on other chromosomes

Question 7

Describe the pathology of AD specifically relating to the destruction of neurones

Answer 7

• Neurones containing acetyl choline are prone to destruction in AD
• Mainly affects neurones in the basal forebrain
• These project to areas of the hippocampus and cerebral cortex

Neurone death occurs in specific brain regions:

• Medial temporal lobe
• Hippocampus
• Amygdala
• Tempero-parietal cortex
• frontal cortex

Question 8

What are the clinical features of AD?

Answer 8

• Starts with mild memory loss
• Gradual deterioration in memory, other cognitive functions and emotional function

Question 9

Describe dementia with lewy bodies

Answer 9

• Progressive cognitive decline with parkinsonian features (e.g. postural tremour rigidity)
• Lewy bodies found throughout the brain
• Associated with psychiatric disturbances (e.g. visual hallucinations., delusions)

Question 10

Describe vascular dementia

Answer 10

• Caused by recurrent thrombo-embolism or small vessel disease
• Abrupt onset and step like prgression
• presence of vascular disease elsewhere
• nocturnal confusion
• emotional lability

Question 11

Describe the two types of drugs used in AD

Answer 11

• Cholineesterase inhibitors
  
  • Prevents acetylcholine from being broken down
  • used for mild - moderate AD
• NMDA receptor agonists
  
  • blocks the action of glutamate (produced in excess by damaged neurons)
  • Used for people with moderate - severe AD

Question 12

Define parkinson’s disease

Answer 12

A goup of disorders characterised by tremor and disturbance of voluntary movement, posture and balance

Question 13

what are the 3 classifications of parkinson’s disease?

Answer 13

• Idiopathic parkinson’s disease
• Parkinsonian syndrome
• Parkinsonism (degenerative brain disorders)

Question 14

What is idiopathic parkinson’s disease and what is parkinsonian syndrome?

Answer 14

Idiopathic parkinson’s disease normally has a gradual late onset, is a primary degenerative condition and responds to dopamine.

Parkinsonian syndrome has the same symptoms as above but is secondary to another neurological condition or is secondary to drug use

Question 15

What are thought to be the causes of parkinsons disease?

Answer 15

• Dopamine producing cell depletion in the substantia nigra
• when about 80% of the dopamine has been lost the symptoms of parkinson’s appear and the level of dopamine will contine to fall slowly over many years

Question 16

Explain normal motor control in terms of dopamine

Answer 16

• Sunstantia nigra produces dopamine
• Dopamine excites the striatum
• The striatum decreases the inhibition on the globus pallidus
• This then stimulates the thalamus
• The thalamus stimulatews the motor cortex
• The stimulation of the motor cortex allows movement to occur in a free way

Question 17

Explain abnormal motor control in terms of dopamine

Answer 17

• The substatia nigra has less dopamine producing cells so less dopamine is produced
• There is therefore less to stimulate the striatum
• There is no decrease on the inhibatory effect on the globus pallidus
• The thalamus isn’t stimulated
• The motor cortex recived diminished exitatory output from the thalamus so movement is inhibited
• slowless in movemernt and movement isn’t free

Question 18

explain the effect dopamine depletion has on muscle tension

Answer 18

• dopamine doesn’t balance out acetylcholine in the effect on the basal ganglia
• No damping effect by the basal ganglia on the reticular formation
• Continued tension throughout movement in muscle

Question 19

Which motor area is impaired in parkinson’s disease and how does this affect the person?

Answer 19

• The supplementary motor system
• There is no background control or moderation of movement for example balance adjustments
• This means that in order to do these movements the person has to actually consciously think about them

Question 20

give the clinical presentation features of parkinson’s disease

Answer 20

• Akinesia - movement is reduced and poor
• Bradykinesia - slowness of movement
• Tremor - a resting pin rolling tremor
• Rigidity
• Lack of postural support
• Difficulty with motor tasks
• Lack of spontaneous movement
• lack of facial expression
• monotone speech
• Abnormal gait - festinating gait

Question 21

what are the other effects of parkinson’s disease?

Answer 21

• Micrographia - smaller writing
• Depression and effective disorders
• Gastrointestinal and other symptoms
• Sleep disorders
• Executive dysfunction - trouble sequencing and ordering tasks

Question 22

What is the management for parkinson’s disease?

Answer 22

• Drug therapy
• Surgary
• Rehabilitation/MDT approach