Question

bio - 201 topic 5: neuronal communication and the brain
practice it
why is it challenging for doctors to treat certain brain - related conditions?
because they need to find drugs that can cross the blood - brain barrier.
because they need to find drugs that are not already in use for other conditions.
because they need to find drugs that can be administered orally.
because they need to find drugs that can be produced at a low cost.
because they need to find drugs that can target specific neurons.

Explanation:

The blood - brain barrier is a selective semi - permeable border that prevents many substances from reaching the brain. Finding drugs that can cross this barrier to treat brain - related conditions is a major challenge.

Answer:

Because they need to find drugs that can cross the blood - brain barrier.