In the past couple of decades our knowledge about the human brain has increased significantly, however it is an extremely complex organ and scientists still know only a fraction about how it works.
At a physical level your brain is made up of 100 billion cells, most of which are a type of cell called a neuron. Neurons produce more than 80 different chemical messengers called neurotransmitters, which are used to transfer information between cells in our brain. Alcohol and other drugs affect the way the brain works by imitating, stimulating, or blocking our neurotransmitters. By changing the amount of certain neurotransmitters in the brain, drugs can influence the way we think, feel and behave.
Drugs and the Brain
Drugs and the Brain
Some drugs, such as heroin, cocaine, amphetamine and nicotine, trigger neurotransmitters in a specific part of the brain called the reward pathway. Stimulating the reward pathway makes people feel very good and become highly motivated to use the substance again. This desire to repeat the behaviour can lead to regular drug use and physical or psychological dependency on the drug.
Our mental health is affected by many things including the amount of neurotransmitters (such as dopamine and serotonin) that we have available. Once we understand this it is easier to see how using drugs can affect our mental health. An imbalance in our brain chemistry is one factor that can trigger the onset of mental illness or make the symptoms of that illness worse.
The brain, along with the spinal cord forms our central nervous system. Among other functions, our central nervous system processes information from our senses; everything we touch, feel, hear and see is a message, which travels through our spine and into our brains for processing. Likewise, our brain sends signals down our spine and out to our peripheral nervous system to tell the limbs to move, the heart to beat and the lungs to take in oxygen.
One way drugs are classified is according to how they impact on the central nervous system. Drugs such as alcohol, heroin, benzodiazepines and cannabis are classed as depressant drugs, because they depress, or slow down activity in the central nervous system, often causing the user to feel sedated. It is because depressants also slow down the heart rate and respiration that too much of one depressant or several taken in combination can lead to a fatal overdose. Some antipsychotic and antidepressant medications are also central nervous system depressants.
Drugs such as amphetamines, methamphetamines, cocaine, ecstasy and nicotine are classed as stimulants, because they stimulate or speed up activity in the central nervous system. Stimulant drugs tend to make people feel more alert and awake. However, speeding up the heart rate too much can lead to an increased risk of heart attack and stroke.
Hallucinogins, such as LSD and magic mushrooms have the effect of scrambling or distorting central nervous system activity, so that messages from your senses get misinterpreted by our brains.