Psychiatric genetics

Question 1

What is huntingdon’s disease?

Answer 1

autosomal dominant genetic mutation in huntingdon gene

Question 2

What does the huntingdon gene do?

Answer 2

Codes for huntingdon protein:
-in huntingdons, expansion of CAG triplet repeats (usually these are 10-35 repeats) which = longer chain of glutamines in protein = huntingdon protein mis-shapen = gradual damage to brain cells
(exact mechanism unknown)

Question 3

What is anticipation?

Answer 3

there’s an earlier onset of symptoms at each generation

happens in huntingdons

Question 4

What are the psychiatric clinical features of huntingdons disease

Answer 4

• depression/anxiety (can be 1st signs)
• psychotic
• blunted (unreactive) affect
• compulsions (gambling/addiction)
• suicidality (can be related to other mental health sx)
• agression/behavioral disturbance

Question 5

Describe the cognitive decline seen in huntingdon’s disease

Answer 5

• decline in executive function (planning/abstract thinking/cognitive flexibility)
• short and long term memory deficits
• dementia: progressive global cognitive decline

Question 6

Describe the motor signs/sx seen in huntingdon’s disease

Answer 6

-choreiform movement
-writhing movements
-gait disturbance
-problems chewing/swallowing/speaking
-rigidity
(all actions requiring muscle control become impaired)

Question 7

what is the presentation of huntingdon’s disease

Answer 7

usually asymptomatic until adulthood

slow onset neuro/psychological sx

Question 8

What is the treatment/test for huntingdon’s disease

Answer 8

currently no cure - only symptomatic treatment

v. easy genetic test

Question 9

What is the most common form of dementia?

Answer 9

Alzheimer’s disease

Question 10

What are the symptoms of alzheimer’s disease

Answer 10

-short term memory dysfunction: episodic/semantic (implicit memory less affected)
-dysphasia
-dyspraxia
-agnosia
-mood sx
-psychosis
-behavioral disturbance/cognitive decline
(eventually require full care leading to end-stage dementia - bed bound/fully dependant/lose swallowing ability - terminal)

Question 11

what is the prognosis of alzheimers disease

Answer 11

Average life expectancy is 7 years after diagnosis

Question 12

What is the pathophysiology of alzheimer’s disease?

Answer 12

formation of extracellular amyloid plaques (which cause inflammation) and neurofibrillary tangles (which may be caused by the inflammation caused by plaques)
-unclear which part of neuropathology causes cognitive dysfunction

Question 13

What is a neurofibrillary tangle made up of?

Answer 13

Tau proteins involved in microtubules are hyperphosphorylated and = tangle

Question 14

Which area of the brain is one of those first affected in alzheimers disease?

Answer 14

nucleus basilis of maynart in basal forebrain where most cholinergic pathways in the brain start
(increasing cholinergic transmission with cholinesterase inhibitors slows decline)

Question 15

what type of alzheimers occurs where more relatives are affected, younger people are affected and there are unusual/atypical features?

Answer 15

familial forms