Final answer:
The adverse effect of valproic acid in chronic neurologic disorders is the elevation of liver enzymes. This is due to the hepatotoxic nature of the drug, which can hinder liver function and lead to liver enzyme elevation, sometimes associated with conditions like hepatic encephalopathy.
Step-by-step explanation:
The correct option related to the adverse effects of valproic acid in chronic neurologic disorders is b) Elevated liver enzymes. Valproic acid is a medication used to treat seizures and bipolar disorder and to prevent migraine headaches. However, one of its known side effects is hepatotoxicity, which can lead to elevated levels of liver enzymes as the drug interferes with the normal function of the liver. Increased platelet count, improved cognitive function, and decreased ammonia levels are not typical adverse effects of valproic acid.
To highlight another point, hepatic encephalopathy is a condition that can be associated with liver dysfunction and can cause neuropsychiatric abnormalities due to the liver's inability to detoxify harmful substances like ammonia. The elevation in liver enzymes can sometimes be linked to conditions that lead to hepatic encephalopathy if the liver damage is severe.