Tag Archives: the brain

The Genetics Behind Huntington’s

Huntington Disease is a rare genetic condition that most people have never even heard of unless a) they study it b) they personally know someone with the disease or c) they are a fan of House. Luckily for me only a) and c) apply in this situation. However, I believe Huntington’s like a variety of other diseases is something the public needs to be educated about because awareness really is the greatest way to inspire research into any field.

As autosomal dominant disorder this makes Huntington’s especially dangerous because as a dominant trait a person only needs one affected allele to develop the disorder. Were the trait recessive such as the trait for hemophaelia, for example, then the likelihood of having Huntington’s is significantly lowered. When a trait is autosomal this means that it is no carried by any of the sex chromosomes (X or Y), rather is carried by any of the other 22 chromosomes the human body has. In Huntington’s the gene affected is located on chromosome 4, specially on the p (upper, shorter) arm.

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The symptoms of Huntington’s has already been discussed on a previous post on basal ganglia disorders; however, in summation it results in damage to the striatum and cerebral cortex causing changes in personality including mood swings, involuntary movements known as hypokinesia and eventually dementia. As is common with most genetic disorders, the symptoms do not appear until adulthood. In Huntington’s the symptoms usually arise around mid-age, but unfortunately it can arise earlier than our 30s or 40s if unlucky. Once symptoms start appearing the person usually has about another 5 to 15 years until death. The age at which symptoms appear directly correlates with the genetics behind the abnormal gene.

Huntington’s is part of numerous diseases including varies ataxias and fragile X syndrome that result due to trinucleotide repeat. Specifically, Huntington’s is due to a repeat of the CAG trinucleotide. Normal alleles carry about 10 to 35 copies, but those suffering from Huntington’s and various other neurodegenerative diseases have more than 40 repeats. People with around 60 repeats with develop Huntington’s around the age of 20. These repeats in CAG result in the production of a “mutant protein” that eventually fill the striatum and cerebral cortex causing degeneration and ultimately death of these brain cells. In healthy individuals the gene involved in Huntington’s encodes for a large protein known as huntingtin (Htt), which when normal enhances the production of a protein (BDNF) necessary for the survival of the cells in the striatum and cerebral cortex.

Stay tuned for a post later this week on current experimental treatment on Huntington’s! Thank you for reading :)

Citation:

Cummings, Michael. “Genetics of Behavior.” Human Heredity: Principles and Issues. 9th ed. Belmont: Brooks/Cole, 2011. 405-06. Print.

Cocaine and the Brain

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As part of a new series on drugs that affect the nervous system, I thought I would begin with cocaine. Unlike many other drugs for some reason cocaine is associated with the rich, famous and successful rather than with troubled teenagers and the homeless. Despite its allure cocaine is a highly additive and highly deadly substance. As a powerful stimulant the powerful high can last anywhere from 15-30  minutes up to an hour. Surprisingly, at least to me, approximately 14% of the American population has tried cocaine (WedMD, 2013) with the largest demographic being males between the age of 18 to 25.

Introduction 

Cocaine like most other recreational drugs affects the brain; if it didn’t there would not be much allure to them really. Most people are after all drawn to drugs because of the escape they offer. Unfortunately, no drugs that play with the mind are to be trusted. As a class A drug, the side effects more than out weighs the highs. Cocaine affects the the neurochemical pathways by blocking the re-uptake of neurotransmitters such as norepinephrine, serotonin, and dopamine.

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As it blocks these three common neurotransmitters it is called a triple re-uptake inhibitor. Drugs that increase the concentration of these specific neurotransmitters are said to be positively reinforcing meaning they create a pleasurably feeling that can become addicting. Addictions such as sex, gambling, eating, etc. can become addictive because they also produce pleasurable feelings that can be self-reinforcing.

The High 

In cocaine users these highs are described as euphoric with accompanying feelings of supremacy, positive mood and also an increase in energy and alertness. You can see why famous detective Sherlock Holmes may have been drawn to such a drug. However, sometimes the high can result in increased levels of anxiety, restlessness, paranoia and irritability. Such symptoms illustrate the dangers of playing with our neurochemical balance; we cannot be certain the pathways we affect are going to result in positive feelings. People with a family history of mental illness are increasingly vulnerable to the effects of cocaine use because such a major flux in their brain chemistry can trigger the onset of disorders ranging from bipolar disorder to schizophrenia.

Physiological Symptoms 

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The dangers of cocaine abuse are not just limited to the brain. Travelling through the blood, cocaine can have devastating effects of the heart, the kidneys, the respiratory system, the gastrointestinal tract and even sexual function. You can read more about these effects on WedMD.

Pharmacology 

Extracted from the coca leaf, cocaine or benzoylmethylecgonine is a crystalline tropane alkaloid (-ine suffix) meaning that it has a crystal-like and nitrogen-based structure that occurs naturally. The coca leaf is mostly found and cultivated in the Andes of South America. From the coca extract the two major forms of cocaine are crack cocaine and powdered cocaine.

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Crack cocaine is the free-base from of the drug meaning it still in its crystalline structure making it possible to be melted down to be smoked.  Powdered cocaine can be dissolved into water or inhaled.

A major danger with cocaine is that it contains a lipophilic group, a hydrophilic group, and an aliphatic group. Meaning it can pass through polar and non-polar membranes, specifically the blood-brain barrier.

Cocaine Addiction 

Over time the reward-system established by frequent cocaine abuse causes damage to the dopamine pathway. This damage means that the pleasure experienced becomes diminished and for the person to experience the same high they must now increase their dosage. Increased cocaine dosage obviously increases the physiological and psychological effects of cocaine addiction.

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Physiological and psychological effects of addiction:

  1. Mood swings
  2. High blood pressure
  3. Panic attacks
  4. Cognitive impairment
  5. Changes in personality
  6. Psychosis: including tactile hallucinations (“coke bugs” or formication)
  7. Paranoia
  8. Insomnia
  9. Tachycardia (increased heart rate)

Symptoms of cocaine withdrawal include:

  1. Depression
  2. Paranoia
  3. Exhaustion
  4. Mood swings
  5. Itching
  6. Anxiety
  7. Insomnia
  8. Craving

Cocaine Overdose and Treatment 

Due to the serious nature of the effects of cocaine abuse, cocaine overdose is common amongst users. The most common cause of death due to overdose is tachycardia, and is a result of the body weakening due to the drug rather than an a lethal dosage. As such, cocaine related deaths are frequently accidental. The increased heart rate elevates blood pressure to the point of  respiratory failure, stroke, cerebral hemorrhage, or heart-failure.

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Unfortunately, even when a person overdosing is brought to an emergency room not much can be done except treat the symptoms. As of right now there is no antidote for cocaine. However, it is still important that these symptoms are treated as it may be able to prevent the above listed causes of cocaine-related deaths.

The symptoms to look for include:

  1. Nausea
  2. Chest pain
  3. Increased heart rate
  4. Fever
  5. Tremors
  6. Vomiting
  7. Seizures
  8. Paranoia
  9. Hallucinations
  10. Delirium

 

Thank you for reading! Please comment with any drug you would like to learn about next.

Citations:

“Cocaine Overdose Symptoms and Treatment.” Cocaine Overdose Symptoms, Signs, and Treatment. Project Know, 2013. Web. 16 Aug. 2013. <http://www.projectknow.com/research/cocaine-overdose/&gt;.

“Cocaine Use and Its Effects.” WebMD. WebMD, n.d. Web. 16 Aug. 2013. <http://www.webmd.com/mental-health/cocaine-use-and-its-effects&gt;.

“DrugFacts: Cocaine.” National Institute on Drug Abuse. NIH…Turning Discovery Into Health®, Apr. 2013. Web. 16 Aug. 2013. <http://www.drugabuse.gov/publications/drugfacts/cocaine&gt;

 

The Brain: Lower-Level Brain Structures

On average humans have a 1:45 ratio between brain to body. This implies that there is a correlation between intelligence and brain to body ratio. However, there are exceptions to this implied correlation. In fact, intelligence is better gauged by the complexity of brain structures.

Primitive vertebrates like sharks, only have structures for basic survival functions – breathing, resting, and feeding. Lower mammals such as dogs are slightly more complex with a brain allowing for emotion and memory. Humans have structures that enable all basic functions, memory, emotion but also structures for information processing and foresight.

The brainstem is the oldest part of the brain as well as central core of it. It begins where the spinal cord swells as it entres the skull; the brainstem is vital for basic automatic survival functions.

  • The medulla is the base of the brainstem: controlling heart rate and breathing.
  • The brainstem-crosser over point is where the nerves from the opposite sides of the body meet.
  • The reticular formation is the nerve network in the brainstem that extends up to the thalamus. It plays an important role in controlling arousal (control of consciousness), specifically our sleep cycle. Other vital roles of the reticular formation includes motor control, visceral control (instinctual), and sensory control.
  • The pons or “bridge” connects the medulla with the cerebral cortex. In addition, the pons helps connect the right and left hemisphere as well controlling autonomic functions such as arousal.
  • The thalamus is the brain’s “sensory switchboard,” located on top of the brainstem. It directs messages to the sensory receptive areas in the cerebral cortex and transmits responses from the sensory areas to the cerebellum and medulla.

brain stem

The cerebellum or the “little brain” is attached to the rear of the brainstem and helps coordinate voluntary movement and balance. The cerebellum of kind of nonverbal memory and learning. It also manages sustaining functions with the spinal cord.

The limbic system is at the border of the brainstem and the cerebral hemisphere and is associated with emotions and drives.

  • The amygdala consists of two almond shaped clusters that influence aggression and fear.
  • The hypothalamus sits below the thalamus and directs maintenance activities such as appetite, thirst and body temperature. Furthermore, it helps govern the endocrine system via the pituitary gland.

Neuroscientists and neuropsychologists can stimulate the pleasure centres in our brain to calm patients. It is also understood that addictive drugs trigger our pleasure system.

brain basic and limbicHow Nootropics Impact the Brain

A class of supplements and drugs called “nootropics” can have a positive impact on parts of the brain. Drugs like piracetam have displayed resistance to adverse brain conditions such as cerebral hypoxia. These nootropic compounds have a affinity brain tissue in the hippocampus and cortex. Nootropic supplements, such as Ashwagandha, can be found online from sites such as fitpowders.com and amazon.com.