« How Alcohol Affects the Brain


General Effects of Alcohol on the Brain

Alcohol can affect several parts of the brain, but in general, alcohol contracts brain tissue and depresses the central nervous system. Also, alcohol destroys brain cells and unlike many other types of cells in the body, brain cells do not regenerate. Excessive drinking over a prolonged period of time can cause serious problems with cognition and memory.

When alcohol reaches the brain, it interferes with communication between nerve cells, by interacting with the receptors on some cells. The alcohol suppresses excitatory nerve pathway activity and increases inhibitory nerve pathway activity. Among other actions, alcohol enhances the effects of the inhibitory neurotransmitter GABA. Enhancing an inhibitor has the effect of making a person sluggish. Also, alcohol weakens the excitatory neurotransmitter glutamine, which enhances the sluggishness even farther.

Chemical Effects of Alcohol on the Brain

To understand how alcohol interferes with brain function, it is necessary to know a little bit about normal brain function. The brain is the control center of the body - it controls all the systems in your body including your muscular system, your respiratory system and your digestive system. But how does the brain control these functions? It does so by using a series of chemical, electrical and physical signals from cell to cell. Within the cell, electrical signals are used for transmission, but between cells, chemical signals are used - these chemical signals are called neurotransmitters.

The gap between cells where neurotransmitters are active is called the synapse. The expelled neurotransmitter travels across the synapse and binds to a protein on the receiving cell membrane called a receptor, which is specific for that neurotransmitter. This action causes some change in the receiving cell, either chemical, electrical or physical, which can excite the receiving cell to perform an action or inhibit the receiving cell from performing an action.

When alcohol is introduced to the synapse, the normal neurotransmission may be affected.

Effects of Alcohol on Brain Parts

Alcohol affects different parts of the brain in different ways.

The Cerebral Cortex and Alcohol | The Limbic System and Alcohol | The Cerebellum and Alcohol | The Hypothalamus, Pituitary Gland and Alcohol | The Medulla and Alcohol


The cerebral cortex and alcohol

The cerebral cortex processes information from your senses, processes thoughts, initiates the majority of voluntary muscle movements and has some control over lower-order brain centers. In the cerebral cortex, alcohol can:

  • Affect thought processes, leading to potentially poor judgement.
  • Depresses inhibition, leading one to become more talkative and more confident.
  • Blunts the senses and increases the threshold for pain.

As the BAC increases, these effects get more pronounced.

The limbic system and alcohol

The limbic system, which consists of the hippocampus and septal area of the brain, controls memory and emotions. The affect of alcohol on this sytem is that the person may experience some memory loss and may have exaggerated states of emotion.

The cerebellum and alcohol

The cerebellum coordinates muscle movement. The cerebral cortex initiates the muscular movement by sending a signal through the medulla and spinal cord to the muscles. As the nerve signals pass through the medulla, they are influenced by nerve impulses from the cerebellum, which controls the fine movements, including those necessary for balance. When alcohol affects the cerebellum, muscle movements become uncoordinated.

The hypothalamus, pituitary gland and alcohol

The hypothalamus controls and influences many automatic functions of the brain (through the medulla), and coordinates hormonal release (through the pituitary gland). Alcohol depresses nerve centers in the hypothalamus that control sexual arousal and performance. With increased alcohol consumption, sexual desire increases - but sexual performance declines.

By inhibiting the pituitary secretion of anti-diuretic hormone (ADH), alcohol also affects urine excretion. ADH acts on the kidney to reabsorb water, so when it is inhibitted, ADH levels drop, the kidneys don't reabsorb as much water and the kidneys produce more urine.

The medulla and alcohol

The medulla (brain stem) influences or controls body functions that occur automatically, such as your heart rate, temperature and breathing. When alcohol affects the medulla, a person will start to feel sleepy. Increased consumption can lead to unconscious. Needless to say, alcohol's effect on the medulla can be fatal if it is excessive.



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Random Facts about Alcohol

Despite alcohol being prohibited to those under 21, 62% of high school seniors claim to have been drunk - half of these individuals claim to have had five or more drinks in a row during the previous 2 weeks.

LD Johnston, et.al., Monitoring the Future Study, Institute for Social Research, University of Michigan, 12/99


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