3000-3999
Sites per thema:
psy0 algemeen
psy1 systemen
psy2 denken
psy3 brein
psy4 individu
psy50 diagnostiek
psy54 behandeling
psy6 optimaal
psy7 groepen
psy8 suboptimaal
psy9 optimaal

3700 Organische Dimensie



Interacties tussen organische

en psychologische processen



Hoe werken medicamenten samen met het psychotherapeutisch proces?

Hoe bepalen hersenfuncties gedrag en persoonlijkheidstrekken?


Neurotransmitters
Geneesmiddelen kunnen worden gebruikt om psychische problemen te behandelen die veroorzaakt worden als de neurotransmitters te veel of juist te weinig werken. (Over de werking van de hersenen en de rol van de neurotransmitters vind je hier een schitterende uitleg.) Er bestaan meer dan 50 verschillende neurotransmitters, elk met een specifiek effect in bepaalde delen van de hersenen. Eenzelfde neurotransmitter kan zelfs een verschillend effect hebben naargelang de plaats in de hersenen.

De best gekende neurotransmitters zijn dopamine, serotonine, noradrenaline en GABA.

Dopamine. De ziekte van Parkinson wordt veroorzaakt door het afsterven van neuronen die de neurotransmitter dopamine bevatten. Anderzijds gaat een overdosis aan dopamine in bepaalde delen van de hersenen gepaard met schizofrenie, gekenmerkt door emotionele problemen, hallucinaties en waanvoorstellingen. Toch is er geen verband tussen deze twee ziektebeelden, verschillende groepen neuronen zijn namelijk verantwoordelijk voor de twee ziekten. Zo worden geneesmiddelen die de dopamine-activiteit belemmeren met succes gebruikt bij schizofreniepatiënten en geneesmiddelen die de dopamine-activiteit stimuleren bij Parkinson-patiënten.
Dopamine heeft waarschijnlijk ook een effect op de gemoedstoestand, evenals noradrenaline en serotonine.

Noradrenaline en Serotonine. Antidepressiva werden bij toeval ontdekt. Artsen die tuberculose behandelden met het geneesmiddel iproniazid stelden bij hun patiënten een sterke verbetering van hun humeur vast. Het geneesmiddel bleek de beschikbaarheid van drie neurotransmitters te verhogen: noradrenaline, serotonine en dopamine. Verschillende bevindingen suggereerden dat een vermindering aan dopamine, noradrenaline en serotonine depressieve aanvallen voorafgaat. Op basis hiervan heeft men de laatste jaren efficiëntere antidepressiva ontwikkeld.

Geneesmiddelen zijn net als neurotransmitters chemische stoffen. Ze remmen of bevorderen de werking van die neurotransmitters.


Algemene regel

Als de scheikundige toestand verandert, verandert ook de psychische toestand.

Als de psychische toestand verandert, verandert ook de scheikundige toestand.


De regel spreekt voor zich. In het extreme geval kan je liefdesverdriet behandelen met een pil! Maar dat is natuurlijk niet de best geïntegreerde behandeling. De beste behandeling is die behandeling die zowel de organische als de psychische processen tegelijkertijd aanpakt, zodat beide processen elkaar kunnen bestuiven en stimuleren. Maw psychotherapie ondersteunt door medicatie.

Een voorbeeld over systematische desensitesatie (SD), een techniek voortspruitend uit de gedragstherapie. De basisgedachte van SD is het angstbeeld te deconditioneren door in een ontspannen toestand het angstbeeld op te roepen en tegelijkertijd de ontspanning te bevorderen of te behouden. De praktijk gaf nu aan dat het resultaat van SD eveneens bereikt kon worden dmv antidrepressiva (AD), de suggestie gevend dat een fobie een gevolg was van een depressie. Verder onderzoek toonde evenwel aan dat de 'pil' enkel werkt bij 'jonge' fobieën. Fobieën die reeds een functie hebben gekregen, die geneurotiseerd zijn, zijn niet langer vatbaar voor medicatie. De 'pil' werkt niet meer.


Probleemoorzaken
Een probleem heeft altijd, maar dan ook altijd, minstens drie oorzaken die tegelijkertijd voorkomen. Een therapeut die vertrekt van de visie dat een probleem juist één welbepaalde oorzaak heeft (een wijdverbreid uitgangspunt binnen de reguliere geneeskunde ...), is zijn titel niet waard.

Een syndroom ontstaat doordat minstens volgende drie factoren samen voorkomen:
  • gevoeligheid van het subject
  • een trigger, de uitlokkende factor
  • een bevestigende omgeving


De interconnectie
Elk medicament werkt na 15 à 30 minuten, behalve AD. AD werkt pas na 2 weken.

Soms wordt door de geneeskundige industrie beweert dat ze een geneesmiddel hebben dat reeds na 6 à 9 dagen werkt, maar die bewering is gestoeld op de Hamilton-test, meer bepaald de HAM-D-test. Deze meet tegelijkertijd derpressie en angst. De verbetering die na 6 à 9 dagen optreedt is binnen de angst; de depressie is echter nog onbeïnvloed.

De reden dat AD trager werkt, kan best uitgelegd worden aan de hand van een metafoor. Veronderstel een onderzeeër die zijn ballasttanks leegblaast en begint te stijgen. Zo lang hij stijgt zie je aan de oppervlakte niets. Pas als hij het wateroppervlakte doorbreekt neem je hem waar. Zo is het ook met AD. Je ziet een hele tijd niets, tot op het punt dat de verbetering doorbreekt.
De termijn van 14 dagen is net dezelfde als de termijn na dewelke een subject depressief wordt bij constante droomdeprivatie. Na 14 dagen is het lichaam verplicht de onverwerkte frustraties, die anders via dromen worden verwerkt, op een andere manier uit te werken, namelijk via depressie.

Geneesmiddellen wijzigen de scheikundige toestand, waardoor de psychische toestand verbetert.

Psychotherapie doet hetzelfde als medicatie, maar dan omgekeerd. Psychotherapie wijzigt de psychische toestand waardoor de scheikundige toestand verbetert.

Door psychotherapie te combineren met medicatie wordt de kans geboden minder neuroleptica te moeten geven aan de patient.


Voorbeeld
Door AD voor te schrijven bij cerebrale contactstoornissen (lichte trauma's aan de hersenen, meestal ontstaan door geboortemoeilijkheden) werden verrassende resultaten vastgesteld. AD verhelpt op prachtige wijze concentratieproblemen die tot frustraties of zelfs tot depressies zijn geworden. Er is dan ook een trend ontstaan om AD voor te schrijven, voornamelijk tricyclische.

Coma: how to predict whether severely brain-damaged patients will regain consciousness.
zie BBC.

Autism parents 'infection risk'Caring for children with developmental problems such as autism or Down's syndrome can weaken parents' immune systems, research suggests.

http://news.bbc.co.uk/2/low/health/7513661.stm


Scan 'detects obsessive disorder'Scientists say they have pinpointed differences in the way the brains of people with obsessive-compulsive disorder (OCD) work.

http://news.bbc.co.uk/2/low/health/7507970.stm


Evidence of 'risk-taking' brain
Minder onderdrukking van de DA-productie leidt tot meer risico-nemend gedrag [ http://news.bbc.co.uk/2/low/health/7802751.stm ]
Scientists say they have found physical evidence of brain differences which may drive "thrill-seekers" to act impulsively or dangerously.
A small study from Vanderbilt University in the US found the biggest "risk-takers" processed a brain "reward" chemical dopamine differently.
Scans spotted fewer "receptors" for the chemical on the cells which make it.
The Journal of Neuroscience study could help explain why some are vulnerable to drug abuse and other addictions.

"Our research suggests that in high novelty-seeking individuals, the brain is less able to regulate dopamine"
Dr David Zald
Vanderbilt University
Animal experiments have already shown that, like humans, some respond differently to novel environments - and those who explore them are more likely to self-administer cocaine when given the chance.
This behaviour is believed to be bound up in the activity of dopamine, a brain hormone which, among other things, can produce a sense of enjoyment connected with certain activities.
Dopamine-producing cells have an inbuilt self-regulating system which is supposed to stop them making too much of the hormone.
"Autoreceptors" on the surface of these cells respond to rising levels by cutting down production.
Rats which show more impulsive behaviour also have fewer of these autoreceptors, and the Vanderbilt scientists set out to see if this was also true in humans.
Free-spenders
They used PET scans to look at the level of dopamine autoreceptors in 34 healthy humans, who had also been quizzed to find out their personality type.
Just as in the animals, a propensity towards thrill-seeking, spending money freely, and spontaneity, could be linked to lower levels of autoreceptors.
Dr David Zald, who led the study, said: "We've found that the density of these dopamine autoreceptors is inversely related to an individuals interest in and desire for novel experiences.
"Our research suggests that in high novelty-seeking individuals the brain is less able to regulate dopamine, and this may lead these individuals to be particularly responsive to novel and rewarding situations that normally induce dopamine release."


Brain's adventure centre located
Centrum voor "avontuurlijkheid" gevonden [ http://news.bbc.co.uk/2/low/health/7469730.stm ]
Scientists have located a region of the brain that encourages humans to indulge in adventurous behaviour.
Sophisticated scans showed the region, located in a primitive area of the brain, is activated when people choose unfamiliar options.
The researchers believe this suggests that taking a chance is an ancient human trait that may have given humans an evolutionary advantage.
The University College London study features online in the journal Neuron.

"It makes sense to try new options as they may prove advantageous in the long run"
Dr Bianca Wittmann
University College London
The research took place at UCL's Wellcome Trust Centre for Neuroimaging.
Volunteers were shown a selection of images with which they had already been made familiar.
Each card had a unique probability of reward attached to it and, over the course of the experiment, the volunteers would be able to work out which selection would provide the highest rewards.
However, when unfamiliar images were introduced the researchers found that volunteers were more likely to take a chance and select one of these options than continue with their familiar - and arguably safer - option.
Using fMRI scanners, which measure blood flow in the brain to highlight which areas are most active, the researchers showed that when the subjects selected an unfamiliar option an area of the brain known as the ventral striatum lit up, indicating that it was more active.
The ventral striatum is in one of the evolutionarily primitive regions of the brain - suggesting that the process can be advantageous and will be shared by many animals.
Lead researcher Dr Bianca Wittmann said: "Seeking new and unfamiliar experiences is a fundamental behavioural tendency in humans and animals.
"It makes sense to try new options as they may prove advantageous in the long run.
"For example, a monkey who chooses to deviate from its diet of bananas, even if this involves moving to an unfamiliar part of the forest and eating a new type of food, may find its diet enriched and more nutritious."
Potential for exploitation
The researchers believe that making a new choice that turns out to be beneficial stimulates release of mood-changing chemicals such as dopamine, which make it more likely that we will continue to be adventurous in the future.
However, the researchers said that making new choices was often a fruitful strategy and also potentially made us more vulnerable to exploitation - for instance by the advertising industry.
Dr Wittmann said: "I might have my own favourite choice of chocolate bar, but if I see a different bar repackaged, advertising its 'new, improved flavour', my search for novel experiences may encourage me to move away from my usual choice.
"This introduces the danger of being sold 'old wine in a new skin' and is something that marketing departments take advantage of."
Professor Nathaniel Daw, now at New York University, who also worked on the study, said rewarding the brain for novel choices could have a more serious side effect.
"In humans, increased novelty-seeking may play a role in gambling and drug addiction, both of which are mediated by malfunctions in dopamine release."
Professor Seth Grant, of the Wellcome Trust Sanger Institute, said the ability to recognise novelty pre-dated the evolution of the striatum, as it had been identified in primitive invertebrates, such as the octopus, which do not have the structure.
However, he said it was probable that the striatum had helped more sophisticated species, including man, to refine the ability.

IS SCHIZOPHRENIA A BY-PRODUCT OF HUMAN EVOLUTION?


ScienceDaily (Aug. 5, 2008) — Metabolic changes responsible for the evolution of our unique cognitive abilities indicate that the brain may have been pushed to the limit of its capabilities. Research published today in BioMed Central's open access journal Genome Biology adds weight to the theory that schizophrenia is a costly by-product of human brain evolution.

Philipp Khaitovich, from the Max-Planck-Institute for Evolutionary Anthropology and the Shanghai branch of the Chinese Academy of Sciences, led a collaboration of researchers from Cambridge, Leipzig and Shanghai who investigated brains from healthy and schizophrenic humans and compared them with chimpanzee and rhesus macaque brains. The researchers looked for differences in gene expression and metabolite concentrations and, as Khaitovich explains, "identified molecular mechanisms involved in the evolution of human cognitive abilities by combining biological data from two research directions: evolutionary and medical".

The idea that certain neurological diseases are by-products of increases in metabolic capacity and brain size that occurred during human evolution has been suggested before, but in this new work the authors used new technical approaches to really put the theory to the test.
They identified the molecular changes that took place over the course of human evolution and considered those molecular changes observed in schizophrenia, a psychiatric disorder believed to affect cognitive functions such as the capacities for language and complex social relationships. They found that expression levels of many genes and metabolites that are altered in schizophrenia, especially those related to energy metabolism, also changed rapidly during evolution. According to Khaitovich, "Our new research suggests that schizophrenia is a by-product of the increased metabolic demands brought about during human brain evolution".
The authors conclude that this work paves the way for a much more detailed investigation. "Our brains are unique among all species in their enormous metabolic demand. If we can explain how our brains sustain such a tremendous metabolic flow, we will have a much better chance to understand how the brain works and why it sometimes breaks", said Khaitovich.


Journal reference:
  1. Khaitovich et al. Metabolic changes in schizophrenia and human brain evolution. Genome Biology, 2008 (in press) [link]





What Does IQ Really Measure?
by Michael Balter on 25 April 2011, 3:02 PM



ENLARGE IMAGE


Effort helps makes you smart? Kids who are more highly motivated on IQ tests achieve higher scores.

Credit: iStockphoto


Kids who score higher on IQ tests will, on average, go on to do better in conventional measures of success in life: academic achievement, economic success, even greater health, and longevity. Is that because they are more intelligent? Not necessarily. New research concludes that IQ scores are partly a measure of how motivated a child is to do well on the test. And harnessing that motivation might be as important to later success as so-called native intelligence.
Researchers have long debated what IQ tests actually measure, and whether average differences in IQ scores--such as those between different ethnic groups--reflect differences in intelligence, social and economic factors, or both. The debate moved heavily into the public arena with the 1994 publication of The Bell Curve by Richard Herrnstein and Charles Murray, which suggested that the lower average IQ scores of some ethnic groups, such as African-Americans and Hispanics, were due in large part to genetic differences between them and Caucasian groups. That view has been challenged by many scientists. For example, in his 2009 book "Intelligence and How to Get It," Richard Nisbett, a psychologist at the University of Michigan, Ann Arbor, argued that differences in IQ scores largely disappear when researchers control for social and economic factors.
New work, led by Angela Lee Duckworth, a psychologist at the University of Pennsylvania, and reported online today in the Proceedings of the National Academy of Sciences explores the effect of motivation on how well people perform on IQ tests. While subjects taking such tests are usually instructed to try as hard as they can, previous research has shown that not everyone makes the maximum effort. A number of studies have found that subjects who are promised monetary rewards for doing well on IQ and other cognitive tests score significantly higher.
To further examine the role of motivation on both IQ test scores and the ability of IQ tests to predict life success, Duckworth and her team carried out two studies, both reported in today's paper. First, they conducted a "meta-analysis" that combined the results of 46 previous studies of the effect of monetary incentives on IQ scores, representing a total of more than 2000 test-taking subjects. The financial rewards ranged from less than $1 to $10 or more. The team calculated a statistical parameter called Hedge's g to indicate how big an effect the incentives had on IQ scores; g values of less than 0.2 are considered small, 0.5 are moderate, and 0.7 or higher are large.
Duckworth's team found that the average effect was 0.64 (which is equivalent to nearly 10 points on the IQ scale of 100), and remained higher than 0.5 even when three studies with unusually high values were thrown out. Moreover, the effect of financial rewards on IQ scores increased dramatically the higher the reward: Thus rewards higher than $10 produced values of more than 1.6 (roughly equivalent to more than 20 IQ points), whereas rewards of less than $1 were only one-tenth as effective.

In the second study, Duckworth and her colleagues analyzed data from an earlier study of more than 500 boys from Pittsburgh, Pennsylvania, whose IQs were tested in the late 1980s by a team from the University of Wisconsin, Madison. During the IQ test, the boys, whose average age was 12.5 years, were videotaped; then observers trained to detect signs of boredom and lack of motivation (such as yawning, laying their heads on the table, or looking often around the room) viewed the videos and assigned motivation scores.
Researchers followed the boys over time, and when the boys reached early adulthood (average age 24), 251 of them agreed to a series of interviews about their educational and job achievements (there were no differences in IQ or other key factors between those boys who participated and those who didn't.)
Duckworth's team analyzed the results of these earlier studies to see what they said about the relationship between motivation, IQ scores, and life success. By constructing a series of computer models of the data, the team found that higher motivation accounted for a significant amount of the differences in IQ scores and also in how well IQ predicted later success in life. For example, differences in motivation levels accounted for up to 84% of the differences between the boys in how many years of school they had completed or whether they had been able to find a job. On the other hand, motivation differences accounted for about only 25% of the differences in how well they had done in school as teenagers. According to the researchers, that suggests that native intelligence does still play an important role in both IQ scores and academic achievement.
Nevertheless, the Duckworth team concludes that IQ tests are measuring much more than just raw intelligence--they also measure how badly subjects want to succeed both on the test and later in life. Yet Duckworth and her colleagues caution that motivation isn't everything: The lower role for motivation in academic achievement, they write, suggests that "earning a high IQ score requires high intelligence in addition to high motivation."
The study has important social policy implications, Duckworth says. "I hope that social scientists, educators, and policy makers turn a more critical eye to any kind of measure, intelligence or otherwise," she says, adding that how hard people try "could be as important to success in life as intellectual ability itself." Duckworth suggests that admissions to programs for "gifted and talented" children should not be based on IQ scores alone, but also on "who wants to do the work."
Nisbett agrees that the study is "tremendously important in its implications." Motivation, along with self-discipline, "are crucial," Nisbett says. "A high IQ and a subway token will only get you into town."
Lex Borghans, an economist at the Maastricht University in the Netherlands, who has also studied the relationship between intelligence tests and economic success, says the new report shows that "both intelligence and personality matter." Even if native intelligence cannot be increased, Borghans says, "there might be other routes to success."