Organic Mental Disorders

Question 1

What are organic mental disorders?

Answer 1

Mental disorders that are due to common, demonstrable aetiology in cerebral disease, brain injury or other insult leading to cerebral dysfunction.

Question 2

What is the difference between primary and secondary organic disorders?

Answer 2

Primary - direct effect on the brain

Secondary - systemic diseases that affect the brain in addition to other systems. E.g. endocrine, substances.

Question 3

What are some common features of organic disorders?

Answer 3

Cognitive - memory, intellect, learning.
Sensorium - consciousness, attention.
Mood - depression, elation, anxiety
Psychotic - hallucinations, delusions.
Personality and behavioural disturbance.
Onset - any age but most tend to start in adult or later life.

Question 4

What are some examples of acute/sub-acute organic mental disorders?

Answer 4

Delirium
Organic mood disorder
Organic psychotic disorder

Question 5

What are some examples of chronic organic mental disorders?

Answer 5

Dementia
Amnesic syndrome
Organic personality change

Question 6

What are the presenting features of delirium?

Answer 6

Impairment of consciousness and attention. 
Global disturbance of cognition
Psychomotor disturbances
Disturbance of sleep-wake cycle. 
Emotional disturbance. 

“Brain failure”

Question 7

What is the characteristic onset of delirium’s presenting features?

Answer 7

Rapid onset
Diurnally fluctuating
Duration less than 6 months

Question 8

What are some causes of Delirium?

Answer 8

Medications e.g. anticholinergic drugs, sedative hypnotics, decongestants, anti-asthmatics.

Drug abuse - amphetamine, cocaine, hallucinogens.

Withdrawal syndromes - alcohol, benzodiazepines, barbiturates.

Metabolic - Hepatic encephalopathy, uraemia, hypoglycaemia, hypoxia, acidosis etc.

Vitamin deficiencies- thiamine, vitamine B12, nicotinic acid

Endocrinopathies

Infections - meningitis, encephalitis, brain abscess.

Neurological causes - head injury, stroke, hypertensive encephalopathy, intracranial neoplasms.

Toxins and industrial exposures - carbon monoxide, carbon disulphide, heavy metals.

Others - SLE, cerebral vasculitis, paraneoplastic syndromes.

Question 9

What is the mechanism of Delirium?

Answer 9

Pathophysiology unclear

• GABAergic and cholinergic neurotransmitter systems
• Central cholinergic deficiency
• Increased dopaminergic activity
• Direct neurotoxic effect of inflammatory cytokines.

Question 10

What medications may be used in the treatment of Delirium?

Answer 10

Antipsychotics -caution in withdrawal states as there is a seizure risk.
Benzodiazepines
Promethazine - anticholinergic. caution in elderly.

Question 11

What is amnesic syndrome?

Answer 11

Syndrome of impairment of recent and remotely memory.
Immediate recall is preserved.
New learning is reduced
Anterograde amnesia
Disorientation in time
retrograde amnesia (may lessen overtime, temporal gradient - worse for recent events)
Confabulation
Perception and other cognitive functions preserved.

Question 12

Where do lesions occur typically in amnesia syndrome?

Answer 12

Hypothalamic-diencephalic system or Hippocampal region.

Question 13

What are some causes of Diencephalic damage in Amnesia Syndrome?

Answer 13

Korsakoff’s syndrome (alcoholic and non-alcoholic)
3rd ventricle tumours an cysts
Bilateral thalamic infarction
Post subarachnoid haemorrhage.

Question 14

What are some causes of Hippocampal damage in Amnesia Syndrome?

Answer 14

Herpes simplex virus encephalitis
Anoxia
Surgical removal of temporal lobes
Bilateral posterior cerebral artery occlusion. 
Closed head injury
Early Alzheimer's disease

Question 15

What is the treatment for Amnesic Syndrome?

Answer 15

Depends on cause

Prevention of alcohol amnesic syndrome - parenteral vitamin b1 then remain on oral thiamine.