WATCH: The effect of drugs on the brain

This story is a supplement to Philstar.com NewsLab's special report on Duterte's war on drugs.

MANILA, Philippines — On the day he was sworn into office, President Rodrigo Duterte gave a speech to a crowd in a Manila slum in which he called on ordinary citizens to kill drug addicts in their own community.

Almost three months later, more than 3,000 suspected drug offenders were reported killed in the government’s “Double Barrel” drive—both from legitimate police operations and vigilante-style or unexplained killings.

The rising body count has shocked the world and sparked alarm among global human rights groups, including the United Nations. Irked by criticisms, Duterte took pains to explain why drug users are dangerous, especially meth or shabu users who usually resist arrest by fighting back at police officers.

“You must remember that those who are already in shabu for almost one year, they are dead. They are the living walking dead. They are of no use to society anymore,” he said.

But what’s in illegal substances that makes it difficult to quit? The answer, according to health experts, lies in the brain.

“In a very layman’s explanation, it (drugs) really destroys the brain. Tinutusta 'yung utak,” said Dr. Jerome Go, a psychiatrist at the Chinese General Hospital and the University of the East Ramon Magsaysay Memorial Medical Center.

Under the influence of drugs, users could do some things that are not really their own willing or not properly calculated.

“Yes, it could result (in) something destructive or disastrous,” the psychiatrist added.

Dr. Alfonso Villaroman, chief of the Bicutan Treatment and Rehabilitation Center, said, however, that there should be a distinction between drug users and drug addicts. These categories should not also be equated with drug dependents.

Those falling under these latter categories, he said, should be treated as patients because there is a road to recovery.

— Philstar.com NewsLab; Interview by Denison Rey Dalupang; Video by Efigenio Toledo IV