Brain Structure, Brain function, and drug design differences in Women and Men

    The nervous system of the body is responsible for sensory, integration of information, and response to stimuli. It is also responsible for complex thought, memory, and personality. The brain is the primary organ of the nervous system and can be thought of as the central controller of the body. The brain is very complex and is still not understood how different segments of the brain have different jobs and how they work together with biochemical molecules to produce memory, learning, personality, and a variety of other complex functions that makes the human mind. Women's and men's brains are different, and the structure and function of different brains and their neurotransmitters help us understand the function of the brain, and our ability to design drugs that impact the brain.

     There are many differences between male and female brains, major differences in not only the psychology of the brain but the chemistry and biology as well. They found that male brains use 7 times more gray matter while females use 10 times more white matter. Gray matter is the localized parts of the brain that relate to information and action centers in the neurons. This is why when men are deeply focused on a single task, they do not notice their surroundings. White matter is the network connection of the brain that connects events and allows for transitions between tasks. This is why women are often better at multitasking and can engage in conversation while doing another task. However, this is not the only structural difference. Females have a larger hippocampus than males do. The hippocampus is related to the memory center of the brain. This is why females are better at remembering details than males, because of the larger hippocampus. Another interesting detail was that during development females develop a verbal center on both sides of their brains compared to males. This is why girls often talk more when explaining details compared to males who have fewer verbal centers and in turn use fewer words.

     

    There are also chemical processing differences in the brain between genders. Serotonin, testosterone, estrogen, and oxytocin are neurochemicals that help the brain form connections and process thought. Males tend to have ADHD and cannot sit still for as long as females can. Evolutionary experts have deemed this back to evolution and state that these traits tend to come from the hunter-gatherer aspect of early human life. However, this has to do with the levels of serotonin produced in the brain. Serotonin, known as the chemical of happiness, controls the body temperature, breathing, and other functions of the body, which will help to relax the body and in turn help the individual to sit still. Because women produce more, they are better able to sit still for long periods compared to men. This is a reason why men are more often diagnosed with ADHD compared to women. Also with serotonin, while females produce more on average, this chemical is secreted far more slowly than the male brain, which is another theory on why women suffer from depression more than men do because the spike in serotonin takes longer to go into effect. Additionally, men produce less oxytocin than women do, which is a neurotransmitter that affects sleep and reduces cortisol levels in the blood. Females produce more oxytocin than men do, which not only makes it easier for women to relax, but it interacts with estrogen to allow females to relax quicker under stressful situations. Men however produce more testosterone than females do, which when it interacts with oxytocin, will make men more aggressive and less able to calm down under stressful situations.

    The neurochemical release of these neurotransmitters can be affected by drugs. For a drug to get to the brain it must be able to pass the blood-brain barrier. The brain’s psychoactive drugs can alter moods and behaviors by activating neurotransmitters in the brain to stimulate chemical processes that produce these emotions. Such examples are drugs that activate dopamine. Dopamine is a neurotransmitter that leads to the reward center of the brain and produces a pleasurable feeling. High levels of dopamine can make one feel that life is great and they are great, this is awesome for people that suffer from depression or negative body image as it can help them learn to feel happy again. However, too much dopamine can lead to irregular heartbeats, schizophrenia, anxiety, headaches, and nausea. Like all chemicals in the body, too much or too little can lead to issues, which is why there must be a balance of the drugs used.

 

    There are lots of ways to trigger dopamine release in the brain. There are natural activities such as exercise, yoga, coitus, delicious foods, and enjoyable hobbies. Some drugs have been known to release dopamine, from nicotine, heroin, and cocaine. While these drugs might be very good at triggering dopamine, they can lead to addiction due to the overabundance of dopamine that is triggered in the brain from these drugs. This leads to a person never being able to feel the euphoric feeling from the abundance of dopamine that is released, this can impair the users’ ability to function properly without the use of the drug, which can lead to violence and outbursts in order to get the drug that allows these feelings to occur. Interestingly there was a case that tried to quantify the amount of dopamine that gets released in different situations. They found that eating chocolate increased dopamine by 50%, coitus caused a 100% spike, but the amphetamines drugs (meth being the most powerful) cause a 1000% increase spike. Based on these numbers alone it is logical to see how when a person gets addicted to a substance that no other activities can compare to the feelings they received from the drug.

 

    There are also drugs that are considered natural supplements that when used can have weird side effects on the brain. One such drug is melatonin. This is a supplement most people take to help relax in the evening from a stressful day and get to sleep faster. The average person uses melatonin at night as a safe sleeping aid, and while the recommended dose is safe, it can produce weird effects on the body. One strange side effect to experience is hallucinations. This happens when there is an overdose of melatonin and can lead to strange dreams. This was also most commonly seen in women, especially those over 60+ years old who take the drug regularly. Most that use this drug have trouble sleeping or have a thrown-off circadian rhythm. We see the use of this drug most often in married women who have trouble sleeping due to the snoring of their husbands. There is also a correlation between these women having weird dreams that seemed like reality to them. Additionally, melatonin overdose can also cause an increase in anxiety in the body through the disruption of hormones, depression can also be caused as a side effect. In addition to psychological effects, melatonin can also affect the body by causing nausea and abnormal cramping as melatonin affects the stomach which can lead to one feeling sick and experiencing cramps, diarrhea, and other stomach issues.

 

    Pharmacokinetics is the study of a drug in the body, how the drug is absorbed, distributed, metabolized, and excreted are key factors of the study when it comes to drug design. Most drugs are consumed orally and are primarily absorbed by the organs of the digestive system such as the stomach and small intestines. However adverse drug events are seen more often in women than in men. For a long time, drug use in women was not well studied because women have hormone cycles that throw off data on how the drug was used. They found that women and men were the exact same only on day 5 of a woman’s cycle. So often female mice were excluded from the studies to get a better look at the drug in male mice without the side effects of hormone cycles. This has caused a large problem in the industry as these drugs are tested on male mice and are being prescribed to female humans without the study of how the hormones in their bodies affect the drug. Men and women are very different and thus the drug dosages and the drugs prescribed should be different. There are many such examples of the pharmacokinetic drug effects between females and males.

 

    An example of a pharmacokinetic drug absorption difference between females and males is that the gastric emptying of solids is significantly slower in women compared to men. In order for a drug to be absorbed it must travel through the gastrointestinal tract and be absorbed through the small intestines. But because women's rates are slower, drug absorption is also slowed. This means that it will take longer for the absorption of a drug to occur in women compared to men.

     

    An example of a pharmacokinetic drug distribution difference in females and males is the regional blood flow differences. Some drugs are distributed in the muscle through injection. Men's and women's muscles do not differ in the location however they can differ in size and in regional blood flow. When exercising women typically have higher heart rates compared to men. This is mainly because women have smaller hearts, and therefore lower stroke volumes and lower blood volume compared to men. So typically, it takes a little longer for distribution to occur in women than in men. Additional factors that affect distribution are body weight, muscle mass, and body fat; all of which differ dramatically between men and women. 

    An example of a pharmacokinetic drug metabolism difference in females and males is the drug antipyrine. It was found that this drug had a shorter half-life in women compared to men. This can be an issue because the drug will circulate longer in females than males, leading to more interactions in the body and can result in overmedication adverse effects in women.

    There are not a lot of examples of a pharmacokinetic drug excretion difference in females and males as drugs are predominantly excreted via the kidneys. One of the only ideas I could find is that a pregnant mother might have a hard time excreting a drug that crosses the placenta barrier into the baby, as the developing baby would process the drug differently and the excretion might be different. Overall, there are a lot of differences in how drugs are used in the body between males and females and there should be better studies dedicated to seeing these differences so they can be applied in the medical world. 

    

    In conclusion, there are many differences between the structure of the brain and brain functions between women and men. By studying these differences in structure, it can better be understood how different behaviors, thinking, and psychological differences came to be. It can also impact our understanding of how the brain works. By observing differences in pharmacokinetics, we can also see how women and men process drugs differently and how pharmacology should be taking into account gender differences in drug design. The structure and function differences of the brain between women and men help us understand the function of the brain, and our ability to design drugs that impact the brain.