The evolution of ADHD

by Eric Schuman

Photo by by Ptit@l

Research has shown that ADHD (Attention deficit / hyperactivity disorder)  is strongly influenced by genes. It seems as if it is related to a problem within the dopamine reward system of the brain. Difficulties with this system could be the  reason that people with ADHD and ADD (attention deficit disorder) seem to have trouble staying focused.

The bad side of  ADHD is pretty obvious: It makes people seem unfocused, hyperactive. But new research proposes that it has benefits. Why else would the genes associated with ADHD still be in the gene pool?  Researchers Dan Eisenberg of Northwestern University and Ben Campbell of the University of Wisconson, Milwakee, think they have an answer. In a study published in BMC Evolutionary Biology, they posit that the sort of activities associated with ADHD—a want of novelty, behavioral flexibility, being hyper-aware in environments—were in fact advantageous to nomadic herdsman. They  go on to link ADHD to obesity. In the modern world where a scarcity of food (for many but clearly not all) no longer exists, dis-inhibition of seeking pleasure from things like food become exaggerated, leading to obesity. Many  children with ADHD have higher BMI’s (body mass index) than their peers, before they go on  medications that often lead to weight loss, they point out.

Campbell, Eisenberg and their collegues (2008) studied a tribe in Kenya. One half had stayed nomadic, and the other had become agricultural. They  explain that within a nomadic context, the ADHD genes are beneficiary. When in a more sedentary context, those same genes result in increased weight and malnutrition. This allele that contains these genes is, of course, connected with ADHD. Therefore, it seems ADHD is both positive and negative.

Seeking sensation through sex and politics

by Molly Tulipan

Bill Clinton and Monica Lewinsky. Warren Harding and Nan Britton. JFK and Marilyn Monroe. Sexual scandal has permeated the White House since America can remember.  Why do leading politicians risk their national reputations and their jobs for extramarital sex? The answer might just lie in their chemical makeup.
Monoamine oxidase A (MOA) is an enzyme that helps our bodies regulate important neurotransmitters like Dopamine. Involved in emotion, learning, and attention, this chemical messenger also has numerous links to risk-taking (Myers, 2006). Zuckerman (2000) discovered that people with sensation-seeking personalities often have excessive levels of Dopamine activity.  This is where MOA comes in to play; people who take fewer risks have higher levels of MOA, because MOA regulates Dopamine. Most people have enough MOA to keep their risk-taking behavior under control. For instance, older people have more MOA than younger people and thereby exhibit less frequent risk-taking behavior. (Ever wondered why young adults are more likely to put themselves in sticky situations than their grandparents?) Females have more MOA than males and are less likely to put themselves in dangerous situations such as drinking and driving and excessive drug use.  What happens when you don’t have sufficient MOA? Essentially, lower levels of MOA yield more dangerous behavior.

In 1971, psychologist Marvin Zuckerman linked levels of MOA to another behavior: sensation seeking, a term he coined.  Zuckerman created a complex personality test called the Sensation-Seeking Scale. Sensation seekers are characterized by a tendency to put themselves in new, exhilarating situations even if they are dangerous. People that pass for sensation seekers as defined by Zuckerman are also easily bored, particularly by repetition in the workplace, “predictable” experiences with others, and conventional work assignments (Zuckerman, 1964, cited in The University of Delaware 1997). It comes as little surprise, then, that sensation seekers might crave the excitement and volatile environment of the White House, and similarly, that their thrill-seeking personalities might also lead them to reckless sexual behavior.

MOA is not the only explanation for sensation seeking. As is always the case with assessing personality traits, risk-taking personalities are a delicate combination of nature and nurture. However, it is interesting to consider that the same traits that lead someone to such a high position of power might also lead them down the risky path of adultery. Even more fascinating: are these traits linked to chemicals in our bodies that lie partly beyond our control?

References

University of Delaware Office of Public Relations (1997). Sensational study: Psychology prof’s work ranks among world’s best. Retrieved October 6, 2008, from http://www.udel.edu/PR/UpDate/97/19/27.html

Author Unknown. (1998, September 9). Sex and the White House. BBC News.  Retrieved October 4, 2008, from http://news.bbc.co.uk/2/hi/events/clinton_under_fire/the_big_picture/167068.stm

Zuckerman, M. (2000, November) Are you a Risk Taker? Psychology Today.  Retrieved October 4, 2008, from
http://psychologytoday.com/articles/pto-20001101-000035.html

Carmichael, M. (2008, 12 March). His Cheating Brain. Newsweek. Retrieved October  2, 2008, from  http://www.newsweek.com/id/121492/output/print

Myers, D. (2006). Psychology (8th Edition in Modules). New York: Worth Publishers.

Do birds get a buzz from singing?

by Allie Tilden

Olds and Milner established in the 1950s that there are specific dopamine reward circuits and pleasure centers throughout the brain that respond to positive stimuli. Drugs, including cocaine and alcohol, have been shown trigger a response in these circuits. Several parts of the brain are involved in this process. The substantia nigra produces large amounts of dopamine, the septal area can be stimulated to release dopamine, and the nucleus accumbens has a large number of dopamine receptors (Meyers, 2007). The artificial stimulation of this  dopamine is associated with positive feelings, but can result in addiction through the processes of desensitization and reduced production. Dopamine receptors in the nucleus accumbens and elsewhere are killed off by the excess neurotransmitter, so that it requires a greater dose of the drug to produce the desired effect each time. But the body will actually produce less dopamine, to try and compensate for the excess.

Luckily, the dopamine-driven pleasure circuits are not just stimulated by drugs.   Natural pleasurable stimuli, such as food or sex,  trigger the same rewards system.  Japanese researchers Ya-Chun Huang and Neal Hessler conducted a study observing the effects of a bird’s song (the zebra finch) on dopamine reward circuits. The male bird has two different songs, one conducted in privacy potentially for practice and the other used to attract females.  Surprisingly they found that the bird produced a response in the dopamine reward circuits when singing for a female but not in privacy.

Why would it be more enjoyable to serenade a partner than just to sing to yourself? Evolution can likely be credited for the positive chemical reaction that occurs in the male finch; if he enjoys singing to females, he is likely to do it more often and therefore attract more mates. It is no stretch to imagine that humans should have a similar response to activities that woo a potential mate. If you can’t stop making yourself look nice, putting on nice clothes or showing off your strength, you may well be stimulating the same brain circuitry that can drive dangerous addictions.  Luckily, these evolution-favored behaviors are much safer than drugs.

References:

Dubuc, B. (2008). The Pleasure Centres.  The Brain From Top to Bottom [Web Site].  Retreived October 30, 2008 from http://thebrain.mcgill.ca/flash/i/i_03/i_03_cr/i_03_cr_que/i_03_cr_que.html

Meyers, D. G. (2007). Psychology (8th ed. in modules). New York: Worth Publishers

Public Library of Science (2008, October 6). Singing To Females Makes Male Birds’ Brains Happy. ScienceDaily. Retrieved October 6, 2008, from http://www.sciencedaily.com­ /releases/2008/10/081003122545.htm

A New perspective on Schizophrenia

By Veronica Swain

After about a half century of schizophrenia treatments that are labeled ‘inadequate’ by most physicians, Dr. Darryle Shoepp, a researcher at the Eli Lilly & Company has developed a drug that takes a different approach of treating the illness with lower side-effects.

Schizophrenia is a severe brain disease that interferes with normal brain and mental functions. The causes are relatively unknown but many believe that genetics and damage of an unborn child’s developing nervous system may be the cause. Beginning with Thorazine, the first medicine used to target the disease’s symptoms such as hallucinations, delusions and paranoia, and continuing with later treatments such as Zxprexa, many drugs have focused on blocking the dopamine receptor sites. By blocking the dopamine receptors sites, the biochemical balances are normalized and the symptoms are relieved. Although these drugs were hailed in the 90’s for their effect on alleviating the aforementioned symptoms, they did little to help the person improve their social communications which would improve their standard of living.

Dr. Shoepp has taken a new approach at treating the disease and has developed the drug LY2140023 which focuses on the neurotransmitter glutamate as opposed to dopamine. Glutamate is an important neurotransmitter that is involved in learning, memory and perception. The new drug works by regulating the reception of glutamate on its main receptors MDMA and AMPA which reduces the symptoms. After successful trial runs on humans, Dr. Shoepp and his colleagues have found that the new drug reduces symptoms of schizophrenia but it also causes fewer movement disorders which is a big improvement from previous drugs. Although the new drug won’t be out until after 2011, the new interest in the neurotransmitter glutamate has caused excitement in researchers who hope that glutamate will be able to provide better treatment to diseases such as Parkinson’s Disease and Alzheimer’s.

Can a couple of puffs really be that bad for you?

by Courtney Kaess

Recently I came along an article from foxnews.com titled Study: Youths Become Hooked on Cigarettes Within Two Days of Inhaling. Intrigued by such a bold headline, I decided to look into the study that the article referenced, and what I found there was definitely surprising. The study, conducted by a group from the University of Massachusetts Medical School, observed 1246 consenting sixth grade students from public schools in six surrounding urban and suburban communities over a four -year period. The study focused on 217 of the subjects who had inhaled from a cigarette over the course of the study. Out of those 217 subjects, 126 showed signs of dependence on nicotine. Ten percent of those 126 lost autonomy within two days of inhaling a cigarette, 25% lost autonomy within 30 days of inhaling their first cigarette, and 50% showed signs of dependence once they had been smoking seven cigarettes a month.

Therefore, even though the original headline I read referenced only about one percent of the original subject population, this study definitely shows that there is evidence that even a small amount of nicotine can trigger dependence on the drug. The use of nicotine causes the release of neurotransmitters such as acetylcholine and norepinephrine, which gives the user a sense of arousal and mental alertness. It also triggers the release of dopamine, which is used as a reward signal in the brain. These pleasurable consequences may explain the frightening effect that tobacco has on our youth.

Death by Meth

by Isabel Vondermuhll

Crystal meth is methamphetamine hydrochloride, the street form of the drug methamphetamine that comes in clear, chunky crystals and is heated and smoked. It is commonly known as crystal, ice and tina.

As for the science behind it, methamphetamine is a chemical stimulant which is similar to amphetamine, but creates a much stronger effect on the central nervous system.  In its legal form, it can be used to treat ADD, narcolepsy and, for short periods of time, obesity.   Mostly, however, it is used illegally for recreational purposes, for weight loss, and to maintain alertness, focus, motivation, and mental clarity for extended periods of time.  Methamphetamine releases high levels of dopamine in the brain, a neurotransmitter that is associated with pleasurable or rewarding experiences.   Meth users tend to display OCD behavior such as obsessive and repeated cleaning.  In withdrawal,  meth users show depression-like symptoms, excessive sleeping and eating, anxiety, and drug craving.

What made me decide to write about Crystal Meth was an acquaintance of mine who has since passed away as a result of his substance abuse.  When I was in high school I interviewed him about crystal meth for a health class presentation.  Click “more” to read some snippets:

The Biology Behind Teen Smoking

by Silvana Rueda

According to the American Lung Association, as many as 6,000 adolescents under the age of 18 start smoking each day, amounting to 800,000 new adolescent smokers annually.  We’re all familiar with the typical psychosocial influences on adolescents (peer pressure, parental influences, advertising, etc), which lead to tobacco experimentation, but recent studies shed light on a new biological reason behind teen smoking and cigarette addiction.  According to a study by the UC Irvine Transdisciplinary Tobacco Use Research Center (TTURC), the rewarding effects of nicotine have a greater response in the adolescent brain than in the adult brain.  Furthermore, researchers also discovered that the first exposure to nicotine produces a greater subsequent behavioral response in adolescents than in adults.

In a study reported on by Science Daily, James Belluzzi and Frances Leslie, tested adult and adolescent rats in controlled environments, monitoring the reinforcing effects of nicotine.  The animals were put in a cage with two distinct chambers, one of which exposed them to nicotine; not surprisingly, the rats preferred the chamber in which they would receive the rewarding drug.  Researchers also discovered that nicotine reinforcement was greatest in adolescent rats.  Following one brief exposure to nicotine, researched noticed extreme motor excitation and increased physical activity in adolescent rats, compared to adult rats.

Nicotine functions like any other addictive drug – by stimulating the release of the neurotransmitter dopamine, in the part of the brain which regulates rewards.  By activating this area and increasing levels of dopamine in the brain’s reward circuits, nicotine produces feelings of pleasure in the smoker.  Other properties of nicotine include the rapid distribution of the drug through the brain; nicotine levels peak within 10 seconds of inhalation, stimulating dopamine release.  However, within a few minutes the acute effects of nicotine disappear, including the associated feelings of pleasure, causing the smoker to continue using the drug, to maintain the drug’s pleasurable effects.

These properties are what make nicotine a very addictive substance.  And this research indicates that nicotine is even more addictive for adolescents than adults, which helps explain why approximately 90% of smokers begin smoking before the age of 21, according to the American Lung Association. Clearly, the danger lies in cigarette experimentation; once adolescents experiment with smoking, they’ll be more likely to get addicted than adults.  Such information promotes the fact that even more emphasis should be placed on discouraging adolescents from smoking.  That first cigarette is no longer as innocuous as it once seemed.