Archiv der Kategorie: brain

Der neurologische Grund für die Siesta

AlphaGalileo meldet

The Spaniards may have been right all along – a siesta after a hearty lunch is natural, new research suggests. Sientists at The University of Manchester have for the first time uncovered how brain cells or ‘neurons’ that keep us alert become turned off after we eat. The findings – published in the scientific journal Neuron this week – have implications for treating obesity and eating disorders as well as understanding levels of consciousness. “It has been known for a while that people and animals can become sleepy and less active after a meal, but brain signals responsible for this were poorly understood,” said Dr Denis Burdakov, the lead researcher based in Manchester’s Faculty of Life Sciences.

Siesta für alle!

Werbeanzeigen

Kiffen hilft vergessen, …

… wenn man’s positiv sehen will. Diese Meldung macht heute die Runde:

Memory, speed of thinking and other cognitive abilities get worse over time with marijuana use, according to a new study published in the March 14, 2006, issue of Neurology, the scientific journal of the American Academy of Neurology.
The study found that frequent marijuana users performed worse than non-users on tests of cognitive abilities, including divided attention (ability to pay attention to more than one stimulus at a time) and verbal fluency (number of words generated within a time limit). Those who had used marijuana for 10 years or more had more problems with their thinking abilities than those who had used marijuana for five to 10 years. All of the marijuana users were heavy users, which was defined as smoking four or more joints per week.
„We found that the longer people used marijuana, the more deterioration they had in these cognitive abilities, especially in the ability to learn and remember new information,“ said study author Lambros Messinis, PhD, of the Department of Neurology of the University Hospital of Patras in Patras, Greece. „In several areas, their abilities were significant enough to be considered impaired, with more impairment in the longer-term users than the shorter-term users.“ (…) In a test where participants needed to remember a list of words that had been read to them earlier, the non-users remembered an average of 12 out of 15 words, the shorter-term users remembered an average of nine words and the long-term users remembered an average of seven words.

Methodenkritik: Viel zu viel psychisch Kranke

Die US-Professoren Allan V. Horwitz (Soziologie) und Jerome Wakefield (Sozialarbeit) vertreten in einem soeben erschienen Fachartikel die Ansicht, dass die in letzter Zeit publizierten enorm hohen Zahlen von Menschen mit unbehandelten Depressionen massiv zu hoch seien. Diese Ziffern seien ein Produkt der gewählten Methodologie, die quasi zwingend zu überhöhten Zahlen führen müsse.

The High Percentages of Depression Have Been Greatly Exaggerated

The Methodology of Community Surveys Leads to an Overestimate of Mental Illness

Washington, DC—According to widely reported community-based research, almost half the U.S. population suffers from depression. But research by two sociologists indicates that percentage is greatly exaggerated or is a misrepresentation. The extraordinarily high rates of untreated mental illness reported by community studies are false, say Allan V. Horwitz, a sociology professor in the Institute of Health at Rutgers University, and Jerome Wakefield, a professor in the School of Social Work at New York University. Community studies rely on standard, closed-format questions about symptoms with no context provided to differentiate between reactions to normal life stress (i.e., a death, a romantic break up, work or school stress) and pathological conditions that indicate clinical mental illness.

Hier der Link zum Originalartikel in der Fachzeitschrift „Contexts“ im .pdf-Format (Alternativlink, falls ersterer nichts liefert). Im Weltgesundheitsbericht der WHO von 2001 steht:

Mental and behavioural disorders are estimated to account for 12% of the global burden of disease

Im Weltgesundheitsbericht von 2002 sind bei den developed countries „neuropsychiatric disorders“ (Das sind: Unipolar depressive disorders, Bipolar disorder, Schizophrenia, Epilepsy, Alcohol use disorders, Alzheimer and other dementias, Parkinson disease, Multiple sclerosis, Drug use disorders, Post-traumatic stress disorder, Obsessive-compulsive disorder, Panic disorder, Insomnia [primary], Migraine, Mental retardation [lead-caused], Other neuropsychiatric disorders) laut Grafik 4.8 für gut 20% der DALYs (ungefähr: durch Tod und Krankheit verlorene Lebensjahre) verantwortlich. Die 450 Millionen, die laut WHO an „mental or behavioural disorder“s leiden, sind 7% der Weltbevölkerung. Horwitz und Wakefield reden in ihrem Artikel eine sehr klare Sprache:

According to large, community-based research studies that the media report with great fanfare, alarming numbers of Americans suffer from mental disorders. The most frequently cited study, the National Comorbidity Survey, claims that half the population suffers from a mental illness at some point. Moreover, these same studies show that few people diagnosed as mentally ill seek professional treatment. Policy discussions, scientific studies, media reports, advocacy documents, and pharmaceutical advertisements routinely cite such figures to show that mental disorder is a public health problem of vast proportions, that few sufferers receive appropriate professional treatment, that untreated disorders incur huge economic costs, and that more people need to take medication or seek psychotherapy to overcome their suffering. Awareness of large numbers of untreated, mentally ill people in the community has reshaped mental health policy, justifying efforts to address this “unmet need for treatment”—for example, by training general practitioners or public school personnel to screen for and treat mental disorders. Despite their rhetorical value, the high rates are a fiction; the studies establish no such thing.

Höhere Ausbildung schützt vor Alzheimer, aber…

… die Krankheit schreitet dafür rascher voran, wenn sie denn mal voll ausgebrochen ist. Das meldet das „Journal of Neurology, Neurosurgery, and Psychiatry“ (Communiqué bei Eurekalert) auf der Basis einer 5 Jahre dauernden Studie an 312 über 65 Jahre alten New YorkerInnen. Die Hypothese: Besser Ausgebildete haben mehr Nervenverbindungen und mehr Synapsen. Damit könnte ev. das Gehirn länger besser umgehen mit den Verheerungen, die Alzheimer anrichtet. Ab einem gewissen Punkt aber sind die verbleibenden Reserven rascher aufgebraucht…

Warum versteh ich Dich?

(Max Planck Gesellschaft) Warum verstehen wir Menschen komplizierte Sätze und unsere nächsten Verwandten – die Affen – hingegen nur einzelne Worte? Nun haben Wissenschaftler des Leipziger Max-Planck-Instituts für Kognitions- und Neurowissenschaften herausgefunden, dass im menschlichen Gehirn zwei Hirnareale für verschiedene Verarbeitungsleistungen der Sprache zuständig sind. Sie stellten fest, dass einfache Sprachstrukturen in einem evolutionär älteren Hirnareal verarbeitet werden, über das auch Affen verfügen. Komplizierte Strukturen jedoch aktivieren Prozesse in einem entwicklungsgeschichtlich jüngeren Hirnareal, das nur höherentwickelte Spezies (Mensch) besitzen. Diese Befunde liefern einen wichtigen Baustein zum Verstehen des menschlichen Sprachvermögens (PNAS, 6. Februar 2006).

Das „chronische déjà vu Syndrom“

Aus der Abteilung „Das kenn ich doch von irgendwo…“

(The Reporter – University of Leeds Newsletter) Many of us have experienced déjà vu – the unsettling sensation of knowing that a situation could not have been experienced, combined with the feeling that it has. It is usually so fleeting that psychologists have until recently thought it impossible to study. But for some people, the feeling of having been there before is a persistent sensation, making every day a ‘Groundhog Day’. Psychologists from Leeds’ memory group are working with sufferers of chronic déjà vu on the world’s first study of the condition.
Dr Chris Moulin first encountered chronic déjà vu sufferers at a memory clinic. “We had a peculiar referral from a man who said there was no point visiting the clinic because he’d already been there, although this would have been impossible.” The patient not only genuinely believed he had met Dr Moulin before, he gave specific details about the times and places of these ‘remembered’ meetings.
Déjà vu has developed to such an extent that he had stopped watching TV – even the news – because it seemed to be a repeat, and even believed he could hear the same bird singing the same song in the same tree every time he went out. Chronic déjà vu sufferers are not only overwhelmed by a sense of familiarity for new experiences, they can provide plausible and complex justifications to support this. “When this particular patient’s wife asked what was going to happen next on a TV programme he’d claimed to have already seen, he said ‘how should I know? I have a memory problem!’” Dr Moulin said.

Moulin führt übrigens auch einen Blog.