Psychiatry In autism spectrum disorder, which of the following is identified as the first biomarker ? A Decreased brain volume in children less than 4 years B Reduced latency of sleep C Increased level of serotonin in the platelets D Increased levels of dopamine 💡 Explanation In autism spectrum disorder, which of the following is identified as the first biomarker ? ✓ Correct Answer: C. Increased level of serotonin in the platelets