Posts tagged psychiatric disorders
Articles and news from the latest research reports.
New form of brain plasticity: Study shows how social isolation disrupts myelin production
Research may prompt new investigations into white matter’s role in psychiatric disorders as well as connections between mood and myelin diseases, like MS
Animals that are socially isolated for prolonged periods make less myelin in the region of the brain responsible for complex emotional and cognitive behavior, researchers at the University at Buffalo and Mt. Sinai School of Medicine report in Nature Neuroscience online.
The research sheds new light on brain plasticity, the brain’s ability to adapt to environmental changes. It reveals that neurons aren’t the only brain structures that undergo changes in response to an individual’s environment and experience, according to one of the paper’s lead authors, Karen Dietz, PhD, research scientist in the Department of Pharmacology and Toxicology in the UB School of Medicine and Biomedical Sciences.
Dietz did the work while a postdoctoral researcher at Mt. Sinai School of Medicine; Jia Liu, PhD, a Mt. Sinai postdoctoral researcher, is the other lead author.
The paper notes that changes in the brain’s white matter, or myelin, have been seen before in psychiatric disorders, and demyelinating disorders have also had an association with depression. Recently, myelin changes were also seen in very young animals or adolescents responding to environmental changes.
"This research reveals for the first time a role for myelin in adult psychiatric disorders," Dietz says. "It demonstrates that plasticity in the brain is not restricted to neurons, but actively occurs in glial cells, such as the oligodendrocytes, which produce myelin."
(Source: eurekalert.org)
Prenatal Testosterone Levels Influence Later Response to Reward
New findings led by Dr. Michael Lombardo, Prof. Simon Baron-Cohen and colleagues at the University of Cambridge indicate that testosterone levels early in fetal development influence later sensitivity of brain regions related to reward processing and affect an individual’s susceptibility to engage in behavior, that in extremes, are related to several neuropsychiatric conditions that asymmetrically affect one sex more than the other.
Although present at low levels in females, testosterone is one of the primary sex hormones that exerts substantial influence over the emergence of differences between males and females. In adults and adolescents, heightened testosterone has been shown to reduce fear, lower sensitivity to punishment, increase risk-tasking, and enhance attention to threat. These effects interact substantially with context to affect social behavior.
This knowledge about the effects of testosterone in adolescence and adulthood suggests that it is related to influencing the balance between approach and avoidance behavior. These same behaviors are heightened in the teenage years and also emerge in extremes in many neuropsychiatric conditions, including conduct disorder, depression, substance abuse, autism, and psychopathy.
Scientists have long known that sex differences influence many aspects of psychiatric disorders, including age of disease onset, prevalence, and susceptibility. For example, according to the World Health Organization, depression is twice as common in women than men, whereas alcohol dependence shows the reverse pattern. In addition to many other factors, sex hormone levels are likely to be important factors contributing to sex differences in psychopathology.
However, research to date has mainly focused on sex hormone levels during adolescence and adulthood, when hormone levels are heightened and built upon substantial prior developmental experience. Sex hormone levels are also heightened during critical periods of fetal brain development, but the impact of such prenatal surges in sex hormone levels on subsequent adult brain and behavioral development has received relatively little attention.
"This study is the first to directly examine whether testosterone in fetal development predicts tendencies later in life to engage in approach-related behavior (e.g., fun-seeking, impulsivity, reward responsivity) and also how it may influence later brain development that is relevant to such behaviors," said first author Lombardo.
In this study, they tested a unique cohort of boys, 8-11 years of age, whose fetal testosterone had been previously measured from amniotic fluid at 13-20 weeks gestation. The boys were scanned with functional magnetic resonance imaging technology to assess changes in brain activity while viewing pictures of negative (fear), positive (happy), neutral, or scrambled faces.
They found that increased fetal testosterone predicted more sensitivity in the brain’s reward system to positively, compared to negatively, valenced facial cues. This means that reward-related brain regions of boys with higher fetal testosterone levels respond more to positive facial emotion compared to negative facial emotion than boys who with smaller levels of fetal testosterone.
In addition, increased fetal testosterone levels predicted increased behavioral approach tendencies later in life via its influence on the brain’s reward system. Lombardo explained, “This work highlights how testosterone in fetal development acts as a programming mechanism for shaping sensitivity of the brain’s reward system later in life and for predicting later tendency to engage in approach-related behaviors. These insights may be especially relevant to a number of neuropsychiatric conditions with skewed sex ratios and which affect approach-related behavior and the brain’s reward system.”
Dr. John Krystal, Editor of Biological Psychiatry, commented, “These remarkable data provide new evidence that hormonal exposures early in life can have lasting impact on brain function and behavior.”
(Source: alphagalileo.org)
Single protein targeted as the root biological cause of several childhood psychiatric disorders
New research in The FASEB Journal suggests that dysfunction in the SRGAP3 protein may lead to schizophrenia, hydrocephalus, mental retardation and some forms of autism in childhood
A new research discovery has the potential to revolutionize the biological understanding of some childhood psychiatric disorders. Specifically, scientists have found that when a single protein involved in brain development, called “SRGAP3,” is malformed, it causes problems in the brain functioning of mice that cause symptoms that are similar to some mental health and neurological disorders in children. Because this protein has similar functions in humans, it may represent a “missing link” for several disorders that are part of an illness spectrum. In addition, it offers researchers a new target for the development of treatments that can correct the biological cause rather than treat the symptoms. This discovery was published in November 2012 print issue of The FASEB Journal.
"Developmental brain disorders such as schizophrenia, hydrocephalus, mental retardation and autism are among the most devastating diseases in children and young adults," said Dusan Bartsch, Ph.D., a researcher involved in the work from the Department of Molecular Biology at the Central Institute of Mental Health at the University of Heidelberg in Mannheim, Germany. "We hope that our findings will contribute to a better understanding, and in the end, to better treatments for these disorders."
Bartsch and colleagues made this discovery using mice with the SRGAP3 protein inactivated. Then they conducted several experiments comparing these mice to normal mice. The mice with inactive SRGAP3 showed clear changes in their brains’ anatomy, which resulted in altered behavior similar to certain symptoms in human neurological and psychiatric diseases. An involvement of SRGAP3 in different brain disorders could indicate that these disorders are possibly connected, as SRGAP3 is a key player in brain development. These different disorders could be connected via the SRGAP3 protein because they all emerge from disturbed development of the nervous system.
"Since Freud put biological psychiatry on the map, we’ve slowly increased our understanding of how mental health is dictated by chemistry," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "Eventually we’ll understand the complex biology underlying most psychiatric illnesses, from genes to proteins to cell signaling to overt behaviors. Along the way, as in this report, we’re likely to find single targets close to the roots of apparently different mental illnesses."
(Source: eurekalert.org)
Every day, we face thousands of decisions both major and minor — from whether to eat that decadent chocolate cupcake to when to pursue a new romantic relationship or to change careers. How does the brain decide? A new study suggests that it relies on two separate networks to do so: one that determines the overall value — the risk versus reward — of individual choices and another that guides how you ultimately behave.