Some clinical implications

Question 1

Ach and LBD

Answer 1

• Ach in brain is reduced in DLB
• cortical choline acetyl transferase (CHAT) is reduced in 85% patients with hallucinations
• may explain altered sleep wake patterns seen in DLB and response of hallucinations to acetylcholinesterase inhibitors

Question 2

Beta adrenoceptors

Answer 2

• chronic antidepressant treatment causes a reduction in beta adrenorecptor density- correlated with therapeutic effects
• unmedicated suicide victims show higher density of beta adrenoceptors
• beta blockaged can reduce peripheral features of anxiety driven by sympathetic overdrive

Question 3

Aberrant salience

Answer 3

• Kapur proposed that in normal people, dopamine attaches significance or salience to external stimulus or an internal thought- this causes a neutral stimulus to become an attention grabbing one
• in psychosis where there is more dopamine, insignificant events become significant and delusions
• antipsychotics ‘dampen salience of these abnormal symptoms, providing a a platform for psychological resolution

Question 4

5-HT and depression

Answer 4

• increased density of 5-HT2 binding sites has been seen in depressed/suicidal patients
• long term antidepressant treatment reduces number of 5HT2 receptors and increases 5-HT1A function