Posts Tagged ‘dopamine’

Schizophrenia is associated with structural and functional alterations of the visual system, including specific structural changes in the eye. Tracking such changes may provide new measures of risk for, and progression of the disease, according to a literature review published online in the journal Schizophrenia Research: Cognition, authored by researchers at New York Eye and Ear Infirmary of Mount Sinai and Rutgers University.

Individuals with schizophrenia have trouble with social interactions and in recognizing what is real. Past research has suggested that, in schizophrenia, abnormalities in the way the brain processes visual information contribute to these problems by making it harder to track moving objects, perceive depth, draw contrast between light and dark or different colors, organize visual elements into shapes, and recognize facial expressions. Surprisingly though, there has been very little prior work investigating whether differences in the retina or other eye structures contribute to these disturbances.

“Our analysis of many studies suggests that measuring retinal changes may help doctors in the future to adjust schizophrenia treatment for each patient,” said study co-author Richard B. Rosen, MD, Director of Ophthalmology Research, New York Eye and Ear Infirmary of Mount Sinai, and Professor of Ophthalmology, Icahn School of Medicine at Mount Sinai. “More studies are needed to drive the understanding of the contribution of retinal and other ocular pathology to disturbances seen in these patients, and our results will help guide future research.”

The link between vision problems and schizophrenia is well established, with as many as 62 percent of adult patients with schizophrenia experience visual distortions involving form, motion, or color. One past study found that poorer visual acuity at four years of age predicted a diagnosis of schizophrenia in adulthood, and another that children who later develop schizophrenia have elevated rates of strabismus, or misalignment of the eyes, compared to the general population.

Dr. Rosen and Steven M. Silverstein, PhD, Director of the Division of Schizophrenia Research at Rutgers University Behavioral Health Care, were the lead authors of the analysis, which examined the results of approximately 170 existing studies and grouped the findings into multiple categories, including changes in the retina vs. other parts of the eye, and changes related to dopamine vs. other neurotransmitters, key brain chemicals associated with the disease.

The newly published review found multiple, replicated, indicators of eye abnormalities in schizophrenia. One of these involves widening of small blood vessels in the eyes of schizophrenia patients, and in young people at high risk for the disorder, perhaps caused by chronic low oxygen supply to the brain. This could explain several key vision changes and serve as a marker of disease risk and worsening. Also important in this regard was thinning of the retinal nerve fiber layer in schizophrenia, which is known to be related to the onset of hallucinations and visual acuity problems in patients with Parkinson’s disease. In addition, abnormal electrical responses by retinal cells exposed to light (as measured by electroretinography) suggest cellular-level differences in the eyes of schizophrenia patients, and may represents a third useful measure of disease progression, according to the authors.

In addition, the review highlighted the potentially detrimental effects of dopamine receptor-blocking medications on visual function in schizophrenia (secondary to their retinal effects), and the need for further research on effects of excessive retinal glutamate on visual disturbances in the disorder.

Interestingly, the analysis found that there are no reports of people with schizophrenia who were born blind, suggesting that congenital blindness may completely or partially protect against the development of schizophrenia. Because congenitally blind people tend to have cognitive abilities in certain domains (e.g., attention) that are superior to those of healthy individuals, understanding brain re-organization after blindness may have implications for designing cognitive remediation interventions for people with schizophrenia.

“The retina develops from the same tissue as the brain,” said Dr. Rosen. “Thus retinal changes may parallel or mirror the integrity of brain structure and function. When present in children, these changes may suggest an increased risk for schizophrenia in later life. Additional research is needed to clarify these relationships, with the goals of better predicting emergence of schizophrenia, and of predicting relapse and treatment response and people diagnosed with the condition.”

Dr. Silverstein points out that, to date, vision has been understudied in schizophrenia, and studies of the retina and other ocular structures in the disorder are in their infancy. However, he added, “because it is much faster and less expensive to obtain data on retinal structure and function, compared to brain structure and function, measures of retinal and ocular structure and function may have an important role in both future research studies and the routine clinical care of people with schizophrenia.”

http://www.eurekalert.org/pub_releases/2015-08/tmsh-rcm081715.php

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Healthy people who are given commonly prescribed mood-altering drugs see significant changes in the degree to which they are willing to tolerate harm against themselves and others, according to a study published Thursday. The research has implications for understanding human morality and decision-making.

A team of scientists from the University College London (UCL) and Oxford University found that healthy people who were given the serotonin-boosting antidepressant citalopram were willing to pay twice as much to prevent harm to themselves or others, compared to those given a placebo. By contrast, those who were given a dose of the dopamine-enhancing Parkinson’s drug levodopa made more selfish decisions, overcoming an existing tendency to prefer harming themselves over others.

The researchers said their findings, published in the journal Current Biology, provided clues to the neurological and chemical roots of common clinical disorders like psychopathy, which causes people to disregard the emotions of others.

The researchers compared how much pain subjects were willing to anonymously inflict on themselves or other people in exchange for money. Out of 175 subjects, 89 were given citalopram or a placebo and 86 were given levodopa or a placebo.

They were anonymously paired up into decision-makers and receivers, and all subjects were given shocks at their pain threshold. The decision-makers were then allowed to choose a different amount of money in exchange for a different amount of shocks, either to themselves or the receivers.

On average, people who were given a placebo were willing to pay about 35p per shock to prevent harm to themselves and 44p per shock to prevent harm to others. Those who were given citalopram became more averse to harm, paying an average of 60p to avoid harm to themselves and 73p per shock to avoid harm to others. This meant that citalopram users, on average, delivered 30 fewer shocks to themselves and 35 fewer shocks to others.

However, those who were given levodopa became more selfish, showing no difference in the amount they were willing to pay to prevent shocks to themselves or others. On average, they were willing to pay about 35p per shock to prevent harm to themselves or others, meaning that they delivered on average about 10 more shocks to others during the trial than those who took a placebo. They also showed less hesitation about shocking others than those given the placebo.

Similar research conducted by the same team in November found that subjects were willing to spare the stranger pain twice as often as they spared themselves, indicating that they preferred harming themselves over others for profit, a behavior known as “hyper-altruism.”

“Our findings have implications for potential lines of treatment for antisocial behavior, as they help us to understand how serotonin and dopamine affect people’s willingness to harm others for personal gain,” Molly Crockett of UCL, the study’s lead author, said in a press release. “We have shown that commonly-prescribed psychiatric drugs influence moral decisions in healthy people, raising important ethical questions about the use of such drugs.

“It is important to stress, however, that these drugs may have different effects in psychiatric patients compared to healthy people. More research is needed to determine whether these drugs affect moral decisions in people who take them for medical reasons.”

http://www.ibtimes.com/antidepressants-affect-morality-decision-making-new-study-finds-1995363

A new drug that gives people superhuman strength, but leads to violent delusions, is gaining attention.

The drug, which has the street name of Flakka, is a synthetic stimulant that is chemically similar to bath salts. Flakka is fast developing a reputation for what seem to be its nasty side effects, including a tendency to give people enormous rage and strength, along with intense hallucinations.”

Even though addicted, users tell us they are literally afraid of this drug,” said James Hall, an epidemiologist at the Center for Applied Research on Substance Use and Health Disparities at Nova Southeastern University in Florida. “As one user recently reported, it’s $5 insanity.”

From what it is to how it may work, here are five facts about Flakka.

1. What is it?

Flakka, which is also called gravel in some parts of the country, is the street name for a chemical called alpha-PVP, or alpha-pyrrolidinovalerophenone. The chemical is a synthetic cathinone, a category that includes the mild natural stimulant khat, which people in Somalia and the Middle East have chewed for centuries. Chemically, Flakka is a next-generation, more powerful version of bath salts. Flakka was banned by the Drug Enforcement Administration in early 2014.

2. What are its effects?

At low doses, Flakka is a stimulant with mild hallucinatory effects.

Like cocaine and methamphetamine, Flakka stimulates the release of feel-good brain chemicals such as dopamine and norepinephrine, Hall said. The drug also prevents neurons, or brain cells, from reabsorbing these brain chemicals, meaning the effects of the drug may linger in the system longer than people anticipate.

3. What are the dangers?

The danger comes from the drug’s incredible potency. A typical dose is just 0.003 ounces (0.1 grams), but “just a little bit more will trigger very severe adverse effects,” Hall told Live Science. “Even a mild overdose can cause heart-related problems, or agitation, or severe aggression and psychosis.”

Because of the drug’s addictive properties, users may take the drug again shortly after taking their first dose, but that can lead to an overdose, Hall said. Then, users report, “they can’t think,” and will experience what’s known as the excited delirium syndrome: Their bodies overheat, often reaching 105 degrees Fahrenheit, they will strip off their clothes and become violent and delusional, he said. The drug also triggers the adrenaline-fueled fight-or-flight response, leading to the extreme strength described in news reports.

“Police are generally called, but it might take four or five or six officers to restrain the individual,” Hall said.

At that point, emergency responders will try to counteract the effects of the drug in the person’s system by injecting a sedative such as the benzodiazepine Ativan, and if they can’t, the person can die, Hall said.

In the last several months, 10 people have died from Flakka overdoses, he said. (Users of PCP, Ecstasy, cocaine and methamphetamine can also experience the excited delirium syndrome.)

4. How is it sold?

According to Hall’s research, alpha-PVP is often purchased online in bulk from locations such as China, typically at $1,500 per kilogram. Doses typically sell on the street for $4 or $5, and because each dose is so tiny, that means dealers can net about $50,000 from their initial investment, as long as they have the networks to distribute the drug.

5. Why are we only hearing about it now?

Evidence suggests the illegal drug has only recently come on the scene. Crime lab reports from seized drugs reveal that seizures of alpha-PVP have soared, from 699 samples testing positive for the drug in 2010, to 16,500 in 2013, according to the Drug Enforcement Administration’s National Forensic Laboratory Information System.

About 22 percent of the drug seizures that tested positive for alpha-PVP came from South Florida, according to the data.

http://www.livescience.com/50502-what-is-flakka.html

Everyone knows it’s easier to learn about a topic you’re curious about. Now, a new study reveals what’s going on in the brain during that process, revealing that such curiosity may give a person a memory boost.

When participants in the study were feeling curious, they were better at remembering information even about unrelated topics, and brain scans showed activity in areas linked to reward and memory.

The results, detailed October 2 in the journal Neuron, hint at ways to improve learning and memory in both healthy people and those with neurological disorders, the researchers said.

“Curiosity may put the brain in a state that allows it to learn and retain any kind of information, like a vortex that sucks in what you are motivated to learn, and also everything around it,” Matthias Gruber, a memory researcher at the University of California, Davis, said in a statement. “These findings suggest ways to enhance learning in the classroom and other settings.”

Gruber and his colleagues put people in a magnetic resonance imaging (MRI) scanner and showed them a series of trivia questions, asking them to rate their curiosity about the answers to those questions. Later, the participants were shown selected trivia questions, then a picture of a neutral face during a 14-second delay, followed by the answer. Afterward, the participants were given a surprise memory test of the faces, and then a memory test of the trivia answers.

Not surprisingly, the study researchers found that people remembered more information about the trivia when they were curious about the trivia answers. But unexpectedly, when the participants were curious, they were also better at remembering the faces, an entirely unrelated task. Participants who were curious were also more likley than others to remember both the trivia information and unrelated faces a day later, the researchers found.

The brain scans showed that, compared with when their curiosity wasn’t piqued, when people were curious, they showed more activation of brain circuits in the nucleus accumbens, an area involved in reward. These same circuits, mediated by the neurochemical messenger dopamine, are involved in forms of external motivation, such as food, sex or drug addiction.

Finally, being curious while learning seemed to produce a spike of activity in the hippocampus, an area involved in forming new memories, and strengthened the link between memory and reward brain circuits.

The study’s findings not only highlight the importance of curiosity for learning in healthy people, but could also give insight into neurological conditions. For example, as people age, their dopamine circuits tend to deteriorate, so understanding how curiosity affects these circuits could help scientists develop treatments for patients with memory disorders, the researchers said.

http://www.livescience.com/48121-curiosity-boosts-memory-learning.html