Anesthetic: An agent that causes insensitivity to pain and is used for surgeries and other medical procedures.
Central nervous system: The brain and spinal cord.
Dementia: A condition of deteriorated mental function.
Dopamine: A brain chemical, classified as a neurotransmitter, found in regions of the brain that regulate movement, emotion, motivation, and pleasure.
Naphthalene: Volatile, active ingredient in mothballs.
Toxic: Causing temporary or permanent effects that are detrimental to the functioning of a body organ or group of organs.
Withdrawal: Symptoms that occur after chronic use of a drug is reduced abruptly or stopped.