Young people at risk of addiction have differences in key brain region
March 4, 2019
Science Daily/University of Cambridge
Young adults at risk of developing problems with addiction show key differences in an important region of the brain, according to an international team led by researchers at the University of Cambridge.
The study adds further evidence to support the idea that an individual's biological makeup plays a significant role in whether or not they develop an addictive disorder.
Adolescence and young adulthood is an important time in a person's development. It is during this time that individuals begin to demonstrate behaviours that are associated with addiction and which suggest that they may be at risk.
One of these behaviours is impulsivity. Sometimes, we need to make quick decisions, for example in response to a danger or a threat. At other times, it is better to hesitate and decide only after careful deliberation. Impulsivity refers to where we respond and act prematurely, without considering the consequences of our actions. While most people occasionally act impulsively, people affected by disorders including attention deficit hyperactivity disorder (ADHD), substance and behavioural addictions, and mental health problems such as depression and anxiety, show much greater levels of impulsivity.
In a study published today in the journal Neuropsychopharmacology, a team of researchers at Cambridge's Department of Psychiatry, in collaboration with a group at Aarhus University in Denmark, has shown a strong association between increased behavioural impulsivity in young adults and abnormalities in nerve cells in the putamen, a key brain region involved in addictive disorders.
As part of the study, 99 young adults aged 16 to 26 carried out a computer-based measure of impulsivity. The researchers also scanned the volunteers' brains using a sequence that is sensitive to myelin content. Myelin is a protein-rich sheath that coats the axis of a nerve cell, analogous to the plastic coating that surrounds electrical wiring, and is essential to fast nerve conduction in the brain and body.
The team found that those young adults who displayed higher measures of behavioural impulsivity also had lower levels of myelin in the putamen. This work builds on similar findings in rodent models of impulsivity from scientists at Cambridge and elsewhere.
"People who show heightened impulsivity are more likely to experience a number of mental health issues, including substance and behavioural addictions, eating disorders, and ADHD," says Dr Camilla Nord of the MRC Cognition and Brain Sciences Unit, lead author on the study.
This suggests that impulsivity is an 'endophenotype', say the researchers; in other words, a set of behavioural and brain changes that increases people's general risk for developing a group of psychiatric and neurological disorders.
"We know that most mental health symptoms are not specific to particular disorders," says Dr Nord. "This work provides an important piece of the puzzle in establishing brain signatures that are general across a number of mental health disorders, rather than specific to any single one."
The putamen is a key brain hub in addiction, sending dopamine signals elsewhere in the brain, and helping mediate how impulsively we behave. "The significance of decreased myelination implies there are tiny microstructural changes in this part of the brain affecting its function, and thereby affecting impulsivity," says senior author Dr Valerie Voon, also from Cambridge.
"The degree of myelination alters the speed and efficiency of neuronal communication, meaning that if a population has decreased myelination only in one particular region, as we show, there is something highly local about any changes in neural speed and efficiency," add co-author Dr Seung-Goo Kim.
Although it is not possible to say definitely whether the decreased myelination causes individuals to behave impulsively, the fact that all participants were healthy and had not been diagnosed with addiction or any other psychiatric diagnosis suggests a more causal link than has been demonstrated in previous studies.
In future, the finding may help in predicting an individual's risk of developing a problem with addiction, say the researchers, but they caution that this would require further research and testing.
The research was funded by the Aarhus University Research Foundation, the Danish Ministry for Social Affairs and the Interior and the UK Medical Research Council. The work was also supported by NIHR Cambridge Biomedical Research Centre.
https://www.sciencedaily.com/releases/2019/03/190304105436.htm
Raising eyebrows on neuroinflammation: Study finds novel role for 'skin plumping' molecule
Neuroscientists identify surprising brain action of cartilage component hyaluronic acid
July 11, 2019
Science Daily/Florida Atlantic University
Scientists have discovered a novel mechanism and role in the brain for hyaluronic acid -- a clear, gooey substance popularized by cosmetic and skin care products. Hyaluronic acid may be the key in how an immune signal moves from the blood stream to the brain, activating the brain's resident immune cells, the microglia. Findings from this study have important implications for better treatments for stroke, neurodegenerative diseases, as well as head injuries.
This clear, gooey substance, which is naturally produced by the human body, has been popularized by cosmetic and skin care products that promote healthier, plumper and more supple skin. Also recognized for its abilities to speed up wound healing, reduce joint pain from osteoarthritis, and relieve dry eye and discomfort, a neuroscientist at Florida Atlantic University's Brain Institute (I-BRAIN) and Schmidt College of Medicine, has discovered a novel mechanism and role in the brain for hyaluronic acid.
In a study published in the journal Brain, Behavior and Immunity, Ning Quan, Ph.D., lead author, a professor of biomedical science in FAU's Schmidt College of Medicine and a member of I-BRAIN, and collaborators, have discovered that hyaluronic acid may be the key in how an immune signal moves from the blood stream to the brain, activating the brain's resident immune cells, the microglia.
This unsuspected molecule may be the main signal passed between these cells, and this new discovery could lead to novel opportunities to shut down brain inflammatory responses. Findings from this study have important implications for better treatments for stroke, neurodegenerative diseases, as well as head injuries.
"We normally think of hyaluronic acid with respect to cartilage formation and also for its role in many processes including cancer progression and metastasis," said Quan. "However, what we have uncovered in our study is a completely unique role for this molecule. We have been able to document a connection between the blood cells and the brain cells, showing that the activating signal passed between these cells is hyaluronic acid."
Quan and collaborators from the Sichuan University, The Ohio State University, and the University of Illinois Urbana-Champaign, demonstrate that inflammation in the central nervous system is oftentimes quenched or restricted, as neurons are extremely vulnerable to inflammation-caused damages. However, this inflammation can be aberrantly amplified through endothelial cell-microglia crosstalk when the brain constantly receives inflammatory signals. Quan's work identified hyaluronic acid as the key signal released by endothelial cells to stimulate microglia and promote oxidative damage.
"To prevent the inflammation from being intensified in the brain, you have to stop the communication between the two cell types," said Xiaoyu Liu, Ph.D., another corresponding author of the study in FAU's Schmidt College of Medicine and I-BRAIN. "We found ascorbyl palmitate, also known as 'Vitamin C Ester,' to be quite effective in inhibiting microglia and reducing the production of inflammatory hyaluronic acid."
In the past, Vitamin C Ester has been widely used as a source of vitamin C and an antioxidant food additive. Now, this latest discovery suggests a novel function of Vitamin C Ester: treating central nervous system inflammation.
"As the newest addition to our Department of Biomedical Science, Dr. Quan's work already is making an important impact on our mission to advance understanding of human health and disease," said Janet Robishaw, Ph.D., senior associate dean for research and chair of the Department of Biomedical Science in FAU's Schmidt College of Medicine. "Long known as a popular skin and joint supplement, this discovery identifies a novel role for hyaluronic acid to potentially treat conditions caused by inflammation in the central nervous system."
Inflammation can occur in the central nervous system as a result of head trauma or stroke, or as part of a systemic immune response. Inflammation within the central nervous system has been associated with chronic neurodegenerative diseases including Alzheimer's disease, Parkinson's disease and multiple sclerosis.
"Neurological disorders such as Parkinson's disease and Alzheimer's disease impact all races, genders, and geographical backgrounds," said Randy Blakely, Ph.D., executive director of FAU's I-BRAIN. "Findings from this study may thus have global implications for how we treat neurodegeneration arising from traumatic brain injuries and brain changes associated with aging and dementia. This exceptional research by Dr. Quan and his colleagues is a testament to the cutting-edge work that is being conducted by our Brain Institute members and the research faculty in FAU's Schmidt College of Medicine."
https://www.sciencedaily.com/releases/2019/07/190711141439.htm