Alcohol effect on the brain has been a subject of debate for decades among Americans.  In the last ten years or so the debate has been over the developmental changes that occur after the age of 21 in certain areas of the brain and how it correlates to behavior.  Alcohol acts upon the Central Nervous System as a stimulant, depressant and an inhibitor.  Alcohol can cross the blood brain barrier and enter the blood and destroy brain cells.  From brain throughout the lifespan develops rostral to caudal and lateral to medial.  According to research, the human brain does not reach full maturity until around age 25.  The legal drinking age should be raised to age 25 to allow the brain to completely develop without impairments of any biological or cognitive functions that could cause major health problems.

Alcohol effects many areas of the brain. However, generally by the current legal age of drinking, 21, the brain is fully developed except for the Prefrontal Cortex.  The prefrontal cortex is the first area of the brain that alcohol affects is the Prefrontal cortex and the Ventral Striatum.  This is the part of the brain that makes up the reward system and regulates impulsive behavior, such as urges, self-control and emotions.  Alcohol impairs their ability for complex planning, to pay attention, to formulate ideas, reason and make rational decisions as well as motor coordination and short term memory.   Alcohol effects the brain in the opposite direction in which the brain develop. Therefore, an underdeveloped prefrontal cortex at age 21 vulnerable to harm from alcohol consumption.

In an animal study on rats by Dr. Heather Richardson and her colleagues at the University of Massachusetts, Amherst, they compared myelin in the prefrontal cortex in adolescent and adult rats who were given alcohol daily for two weeks. Upon examining the rats over several months, they found that the adolescent rats showed a greater reduction in myelination than the adult rats.  A reduction in myelination can cause a reduction in brain size, mental illness, and cognitive deficits. Remember, myelin is important in to protect the axon of neurons and information processing and transmission speeds.  The prefrontal cortex is not operating at its functional capacity at age 21 as it does at age 25.

Another process that the brain continues until the age of 25 is synaptic pruning.  Synaptic pruning is an elimination of synapses that are not being used in order to increase the efficiency of other neural transmissions.  It is like a tweaking process the brain goes through to ensure it is functioning optimally.  Alcohol inhibits the synaptic transmission.  Thus, synaptic pruning can’t occur. If the synaptic pruning doesn’t occur then the brain is unable to properly function. This is a developmental hindrance which will carry over to adulthood well beyond the age of 25.

Alcohol influences the brain in so many ways. It acts upon the Dopamine and Serotonin pathways. Alcohol acts at the Limbic System through the Nucleus Accumbens and Ventral Striatum. This makes since because if myelination and synaptic transmission are impaired by alcohol consumption then nothing in the brain is as it should be.  Whether you know what these pathways are or not, please understand that normal functioning, thought processing, and personality development, especially memory.

Alcohol interferes with Long Term Potentiation (LTP) through neurotransmitter glutamate at the NMDA receptor.  Thus calcium influx is reduced, which causes LTP or memory and learning deficiencies.  Recently researcher have investigated the correlation between age and alcohol as it applies to memory in studies using hippocampal slices taken from adolescent and adult rats. First both groups were not given any alcohol.  The Long Term Potentiation was greater in adolescents than adults. The adolescent rats had a greater magnitude for memory.  Secondly, both groups of rats were given alcohol.  This time the adolescent rats LTP was reduced greatly almost to the point of complete blockage. The adult rats were not affected by the same dosage of alcohol administered as the adolescent rats. However, when given an increased amount of alcohol concentration, their LTP was inhibited.  Other experiments were also done to compare glutamate activity at the NMDA receptor as it responds to stimulation in the hippocampus with and without alcohol concentration.  The results were the same as with LTP.  The adult rats required a higher concentration of alcohol to reduce the NMDA receptor activity in the hippocampal slice in comparison to the adolescent rats.  Thus both studies deduced that adolescent rats have a higher susceptibility to alcohol as it relates to not only hippocampal function but also memory.

It can be said that a large majority of the brain is developed prior to age 21. However, all higher complex functioning of the brain is controlled by the prefrontal cortex. The cortex that is still developing, and pruning well into a person’s mid 20’s.  There have been several arguments as to why the drinking age should even be reduced based on legal freedoms that are extended to people younger than age 25.   You can get a restricted license at age 16. You can vote at age 18.  You are eligible to join the military at age 17.  However, you can’t legally drink until age 21 or rent a car without an adult until age 25.   I can understand why many are confused about what is to be the legal drinking age.  There are missed messages being sent by the vary laws that govern us.   How can we be competent enough to do one thing and not the other?

The legal age for drinking should be raised to protect the individual from long term damage. Biologically speaking, the mind or brain is still growing and unable to make decisions effectively under the influence of alcohol.   That is why if you drink and drive, you lose your license and can’t rent a car.   If you have a DUI or major health problems from alcohol consumption, you are unable to join the military.  Yes many people over the age of 25 have these same problems but 9 out 10 were pre-exposed to drinking prior to the age of 25, which impair brain development.

Alcohol affects the Central Nervous System as a whole but the first point of contact is the Frontal Cortex.  Alcohol affects the cortex myelination, synaptic pruning, and long term potentiation. New research study provides evidence to alcohol’s stimulatory and inhibitory effects on Serotonin and Dopamine pathways that are necessary for the functional, cognitive and physical well-being of an individual.   More importantly that alcohol affects memory formation and hippocampal functions, like long term memory. Persons under the age of 25 are more sensitive to alcohol biologically.  The legal drinking age should be raised to age 25.

References

Keshavan, M. S., Diwadkar, V. A., DeBellis, M., Dick, E., Kotwal, R., Rosenberg, D. R., … & Pettegrew, J. W. (2002). Development of the corpus callosum in childhood, adolescence and early adulthood. Life sciences, 70(16), 1909-1922.

Paus, T. (2005). Mapping brain maturation and cognitive development during adolescence. Trends in cognitive sciences, 9(2), 60-68.

Benes, F. M., Turtle, M., Khan, Y., & Farol, P. (1994). Myelination of a key relay zone in the hippocampal formation occurs in the human brain during childhood, adolescence, and adulthood. Archives of general psychiatry, 51(6), 477-484.

Hiller, S., & Schwartzwelder, H. S. (n.d.). Alcohol’s Effects on the Adolescent Brain What Can Be Learned From Animal Models. NIH, 4, 213-231. Retrieved from http://pubs.niaaa.nih.gov/publications/arh284/213-221.htm

Animal Study Suggests Heavy Drinking in Adolescence Is Associated With Lasting Brain Changes, Memory Deficits. (2014). Retrieved from http://www.sfn.org/Press-Room/News-Release-Archives/2014/Animal-Study-Suggests-Heavy-Drinking-in-Adolescence-Is-Associated-With-Lasting-Brain-Changes