Tag: Psych 100

Can Dizygotic Twins be Equally Affected by a Teratogen Like Alcohol?

What are dizygotic twins? Dizygotic twins are what the average person would call a fraternal twin. A woman’s body typically only releases one egg once a month but sometimes more than one is released, that is how dizygotic twins come about. Dizygotic twins share the same prenatal environment. The average person would believe that a pair of dizygotic twins would be the least common type of twin but in fact they are more common than identical twins. 

In order to understand how a teratogen can affect not only one fetus let alone a set of twins, one must understand what a teratogen is and the process of fetal development. 

Prenatal development occurs in a series of trimesters. The first trimester consists of the egg maturing and the fetus developing body structure as well as organ system development. The first trimester is the first ten to twelve weeks of pregnancy. The second trimester is where the fetus starts to present some sort of movement. The second trimester lasts from weeks thirteen to week twenty-six. Lastly, the third trimester, the final stretch of pregnancy, is where the uterus increases in size and one gives birth. 

Throughout the prenatal development process if some sort of substance harms the fetus it is known as a teratogen. The substance that can cause harm can range from anything like environmental factors, for example, pollution or radiation and can further extend to factors like cigarettes, alcohol, or drugs that may cause harm. Although teratogens don’t always cause harm to the fetus, in larger and longer periods of time it can cause harm.  

To specify how alcohol affects a pair of dizygotic twins, one must understand the effects of Fetal Alcohol Syndrome (FAS) in a singular fetus. If the mother abuses alcohol while pregnant, upon birth the baby will develop or have a lack of development in physical features as well as learning capabilities. In some cases babies can have a wide variety of under-developed features such as a smaller head size, shorter than average height, low body weight, difficulty with attention especially in a school setting which can lead to learning disabilities as well as delays in language and speech, and poor memory. In a set of dizygotic twins, FAS can affect one and not the other. A study found that “one twin had prenatal growth delays, neonatal withdrawal symptoms, and delays in both motor and cognitive function during the first year of life. The catch-up growth occurred during the postnatal period for the affected twin while the other twin was normal at the end of the follow-up at age 17 months”. In that study, they concluded that exposure to alcohol during the second half of pregnancy rather than the first half, greatly increases the risk for brain damage but not lasting postnatal growth. 

The answer to if a teratogen such as alcohol can have an effect on both dizygotic twins would be no, one twin can be effected while the other be a healthy baby with no long-term effects, that doesn’t always give someone the green light to abuse alcohol while pregnant and the baby not have FAS.  

 

 

 

 

 

 

References 

Riikonen, R. S. (1994, November). Difference in susceptibility to teratogenic effects of alcohol in discordant twins exposed to alcohol during the second half of gestation. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/7702696. 

 

Basics about FASDs | CDC. (n.d.). Retrieved from https://www.cdc.gov/ncbddd/fasd/facts.html. 

What Neurotransmitter Is Affected by a Traumatic Brain Injury?

In order to understand what neurotransmitter is affected by a Traumatic Brain Injury, one must understand the basic functions of a neurotransmitter. A neurotransmitter is a chemical that sends signals across the synapses, a structure that enables a neuron to pass an electrical or chemical signal to another neuron, between neurons. These travel across synaptic spaces through a terminal button of one neuron and the dendrite, the branched projections of a neuron that act to conduct electrochemical stimulations that have been received from another neuron, of other neurons binding to the dendrites in neighboring neurons. Different buttons release different transmitters. Also, different dendrites are sensitive to different transmitters. Another important term to understand is an agonist. An agonist is a drug that has chemical properties similar to a particular neurotransmitter which mimics the effects of the neurotransmitter. These agonists bind receptor sites in dendrites that will excite the neuron. An antagonist is a drug that reduces or stops the normal effects of a neurotransmitter. There are six different types of neurotransmitters each serving their own functions and receiving different electrochemical signals and expressing different reactions.

Now that there is an understanding of how neurotransmitters operate, we can find the answer to what neurotransmitter is affected by a Traumatic Brain Injury (TBI). One of the six neurotransmitters that is mostly affected by a Traumatic Brain Injury is Dopamine. Dopamine’s function is that it is involved in the movement, motivation, and emotion. Dopamine produces a feeling of satisfaction and is also involved in learning. A dysfunction that is contributed to posttraumatic brain injury includes damages in the hippocampus, (located under the cerebral cortex), striatum (nucleus in the subcortical basal ganglia of the forebrain), and the frontal cortex. Together these mediate attention, executive functions, learning abilities, and memory. The use of a Dopamine agonist has benefits in memory and attention recovery. Although Dopamine has a commonly known relation with Parkinson’s disease, there is not an increased risk of this disease due to a Traumatic Brain Injury. There are other deficiencies of Dopamine transmission that are related which include PTSD, substance abuse, and short-term memory loss. With these deficiencies there are two phases that can divide brain injury. Phase one also known as the primary phase is a direct mechanical damage of neurons. Phase two includes the promotion of cell death which regress over time.

A scientific study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657731/) has found some ways that hold therapeutic value of targeting the dopamine system include a treatment with a low dose of methamphetamine that can improve behavioral and cognitive functions after Traumatic Brain Injury while being able to restore learning and memory functions to near normal levels. Another way is Bromocriptine which is an agonist with significant antioxidant properties that enhance spatial learning and hippocampal neuron survival.

How is this related to me personally? I have endured two Traumatic Brain Injuries playing soccer. The first concussion was in high school and I did suffer from some deficiencies, I was monitored over several months to see any improvements in brain activity, I also was advised to do exercises that would help improve some functions that were damaged such as memory loss and everyday movements. For example, I had to do eye exercises to help strengthen my eye movement. Another exercise I had to do was a memory test then I would have to work out for a certain amount of minutes then try to remember some of the information before the workout in order to improve my short-term memory under stress. Overtime the workouts would increase in time and the memorization of the information would increase due to improvement in dopamine releasement. Although I underwent all that observation, due to the traumatic brain injury I noticed I was having difficulty reading and having my eyes focus on the words on a page, so I was given reading glasses that had a special prescription to help reduce headaches. After the second traumatic brain injury, my eyesight continued to get worse.

Neurotransmitters are an important part in our body’s functions. Every action has a reaction.