This pace of discovery might be expected given the extreme intricacy of the brain and psychiatric disorders.
“The brain is incredibly complex — we’re talking about tens of billions of neurons with trillions of connections,” says Kozo Kaibuchi, director of the International Center for Brain Science (ICBS) at Fujita Health University, near Nagoya in Japan. “Psychiatric and neurological disorders are also highly diverse — often involving subtle changes on a spectrum rather than one obvious cause.”
On top of that, there are further obstacles that hinder progress in developing treatments for these conditions — the difficulty of imaging inside the human brain; the scarcity of human-like models; and the blood–brain barrier, which prevents most drugs from entering the brain.







