How Substances Change the Mind

Chapter 3: States of Consciousness

Learning Outcomes

Describe how stimulants, depressants, and hallucinogens affect brain chemistry and influence states of consciousness
Identify the cognitive and behavioral effects of substance use, including both short-term and long-term impacts
Use psychological knowledge to make informed decisions about drug use and mental health in real-life situations

Key Terms

depressant: drug that tends to suppress central nervous system activity
hallucinogen: one of a class of drugs that results in profound alterations in sensory and perceptual experiences, often with vivid hallucinations
stimulant: drug that tends to increase overall levels of neural activity; includes caffeine, nicotine, amphetamines, and cocaine
tolerance: state of requiring increasing quantities of the drug to gain the desired effect

The Party Conversation

Imani, a 19-year-old college student, was attending a weekend party with friends. The music was loud, the lights were low, and the atmosphere was relaxed. While chatting in the kitchen, Imani overheard a conversation about "microdosing" psychedelics to improve creativity and mood. Someone else mentioned using stimulants to stay focused during finals.

Imani didn't join in, but the comments stuck. In psychology class, they had just started learning about altered states of consciousness. Imani wondered: What do these substances actually do to the brain? Are they safe? Are the effects as positive as people claim?

A picture of 5 people sitting in a circle and talking

Later that week, Imani read a research article comparing the effects of different psychoactive substances. The study explained how stimulants like amphetamines increase dopamine and norepinephrine, temporarily boosting alertness and energy. Depressants, such as alcohol, slow down brain activity, impairing coordination and judgment. Hallucinogens affect serotonin pathways, altering perception and sometimes triggering anxiety or confusion.

The article emphasized that while some substances may produce short-term changes in mood or cognition, they also carry risks, especially when used without medical supervision. Repeated use can lead to tolerance, dependence, and long-term changes in brain function.

Explore the Concept

Want to understand how different substances affect the brain in real-world scenarios? Check out this short video to learn how stimulants, depressants, and hallucinogens interact with brain chemistry and behavior.

1. On Your Own

Which of the following statements reflect current scientific understanding of substance use? Select the two that apply.

All psychoactive drugs are safe if used occasionally.

Repeated drug use can change brain chemistry and lead to dependence.

Different substances affect different neurotransmitter systems in the brain.

Hallucinogens and stimulants have identical effects on consciousness.

Behind the Brain Effects

3-D rendering of a neuron with glowing synapses, showing dendrites, axon, and neural connections on a dark background

Imani learned that psychoactive substances don't just "enhance" experiences; they alter brain chemistry in ways that can affect memory, attention, and emotional regulation. Stimulants may improve focus temporarily, but they can also increase anxiety and disrupt sleep. Depressants may reduce stress in the moment, but they impair decision-making and can lead to risky behavior. Hallucinogens can distort perception and trigger unpredictable psychological responses.

Researchers caution that while some substances are being studied for therapeutic use, recreational use, especially among young adults, can interfere with brain development and increase the risk of mental health issues.

Imani began to think more critically about the casual way drugs were discussed at the party. They realized that understanding the science behind substances was key to making informed, healthy decisions.

The Mouse Party Simulation

Curious how different substances affect the brain at the cellular level? Explore the interactive Mouse Party simulation to see how various drugs change neurotransmission in real time.

2. On Your Own

Which statement best reflects the role of psychoactive substances in altering consciousness? Select the best answer.

Psychoactive drugs may influence brain function, but their effects are mostly psychological and temporary.

All drugs affect the brain in the same way.

Occasional drug use always improves mental performance.

Psychoactive substances can alter mood and perception by changing brain chemistry, but repeated use may lead to dependence and cognitive changes.

The Conscious Choice

Imani did not feel pressured to try anything, but they appreciated having the knowledge to make informed choices. They started exploring healthier ways to manage stress and improve focus, including mindfulness, exercise, and better sleep habits. "It's easy to hear one side of the story at a party," Imani said. "But learning how substances actually affect the brain helped me think twice, and that's something I'll carry with me."

A picture of a group of runners on a dirt trail

As the semester continued, Imani noticed improvements in their ability to concentrate and manage stress through consistent, intentional habits. They felt more in control of their mental performance and more confident in their decisions. When conversations about drug use came up among peers, Imani shared what they had learned in class and from research, offering facts without judgment. What Imani learned in class and through research became more than just academic insight. It shaped how they approached decisions about their own well-being and gave them the confidence to support others in making informed, thoughtful choices.

Reflect & Respond

Answer the following questions to reflect on key ideas from the case study. Remember to print your work before leaving this page!

How do stimulants, depressants, and hallucinogens affect different brain systems?
Why might some substances carry greater risks than others, especially for young adults?
What factors should someone consider before using a substance to manage stress, focus, or mood?
How can understanding the brain help you make healthier decisions about your mental performance?
How did Imani's understanding of psychoactive substances evolve after the party, and what does this suggest about the importance of scientific literacy in making personal health decisions?

References

Millière, R., Carhart-Harris, R. L., Roseman, L., Trautwein, F.-M., & Berkovich-Ohana, A. (2018). Psychedelics, meditation, and self-consciousness. Frontiers in Psychology, 9, Article 1475. https://doi.org/10.3389/fpsyg.2018.01475
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0).

Yale Medicine. (2022, May 23). How an addicted brain works [Video]. YouTube. https://youtu.be/RZ5LH634W8s?si=l50wV4986tZE3t3m

Photo Credits

Seventyfour on Adobe Stock. "High angle view at multi-ethnic group of young people sitting in circle and sharing ideas in psychology class."

Dr_Microbe on Adobe Stock. "Neurons, brain cells, located in the frontal lobe of the human brain."

coachwood on Adobe Stock. "Group of runners on a dirt trail running."