Which of the following substances may affect the functions of the brain? (I) Alcohol (II) Thinner (III) Cocaine

All of the substances listed can affect the functions of the brain.

(I) Alcohol: Alcohol is a depressant, which means it slows down the functions of the central nervous system, including the brain. It alters the brain's levels of neurotransmitters, which are chemical messengers that transmit signals throughout the body that control thought processes, behavior and emotion. Alcohol can affect the parts of the brain that control movement, speech, judgement, memory, thus causing the short term effects of alcohol like difficulty walking, blurred vision, slurred speech, slowed reaction times and impaired memory.

(II) Thinner: Inhalants like thinner are rapidly absorbed through the lungs into the bloodstream and quickly distributed to the brain and other organs. Within minutes of inhalation, the user experiences intoxication along with other effects similar to those produced by alcohol. Thinner can cause damage to brain cells by preventing them from receiving enough oxygen, which can lead to cognitive problems, and in severe cases, cause death.

(III) Cocaine: Cocaine is a powerful stimulant that directly affects the brain. It floods the brain with dopamine, a neurotransmitter that controls pleasure and movement. The drug prevents dopamine from being recycled, causing excessive amounts to build up in the brain. This flood of dopamine ultimately disrupts normal brain communication and causes cocaine's high. Long-term use can cause changes in the brain's reward system and other brain systems, which can lead to addiction.