This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Psychiatry
Best marker for electroconvulsive therapy: 
Select and explain. 
A. CSF 5 HIAA, B. CSF serotonin, C. Brain derived growth factor, D. CSF dopamine
C: Brain derived growth factor
Answer: C: Brain derived growth factor 
Explanation: Increase in brain derived neurotrophic factor, BDNF mediates the response to ECT and is the best marker for the same.