Study suggests ways to treat these deficits before the psychiatric symptoms develop
Researchers at the University of Montreal and CHU Sainte-Justine Research Centre have traced the origins of ADHD, substance abuse and conduct disorder, and found that they develop from the same neurocognitive deficits, which in turn explains why they often occur together.
"Psychopathology exists on multiple continua of brain function. Some of these dimensions contribute to a multitude of problems, others contribute to specific problems. Together, they explain patterns of comorbidity such as why ADHD and conduct problems co-occur with substance misuse at such a high rate," explained the study's lead author, Professor Patricia Conrod. "Our findings suggest that risk for externalizing problems exist on a continuum in the general population, are easily measured and can be targeted before diagnosable problems arise.
The findings also help reduce stigma and address some of the complexities when diagnosing and treating concurrent psychiatric problems. The implications are that clinicians can manage multiple psychiatric problems by focusing on how a young person is functioning on a fewkey neurocognitive dimensions. The next step is to develop evidence-based intervention strategies that will target these three areas of brain function"
The findings were established by studying the reward sensitivity and decision making patterns of 1,778 European 14-year-olds of comparable demographic profile. The teens were asked to undertake several tasks while undergoing an MRI and answer personality questionnaires.
Clinicians also profiled the participants, once at the time of the testing, and again two years later.. At age 14, 4.4% of participants were identified as having a diagnosis of conduct disorder, ADHD, or both; by 16, this figure had risen to 6.6%. Alcohol and substance abuse were also identified, with 3.7% and 10.6% prevalence respectively at age 14, and 18.0% and 27.1% respectively at age 16.
The researchers were able to use statistical modelling to see what risk factors were linked to which psychiatric symptoms. "This is the first study to model ADHD, conduct disorder and substance use problems in adolescence by using a novel statistical approach that identifies the shared variance among these problems as well as the neurocognitive risk factors that are common across these problems. Three key neurocognitive dimensions were identified as being implicated is most externalizing problems: impulsive action, impulsive choice (valuing immediate rewards over delayed rewards) and reward sensitivity.
A young person's performance and brain function on each of these dimensions were shown to be related to externalizing problems. Self report impulsivity, impulsive actions on a response inhibition task and the extent to which frontal brain regions are hypoactive when committing an impulsive action differentiated youth who were most at risk for ADHD and conduct problems from youth who are at risk for all externalizing behaviours more generally.
Thrill or sensation seeking and abnormal activity in frontal brain regions when anticipating rewards differentiated youth who were uniquely at risk for alcohol misuse relative to those at risk for problems generally." explained Natalie Castellanos-Ryan, first author of the study.
"There has recently been a trend in psychiatry to reformulate diagnostic categories from a dimensional and neuroscience perspective, fueled mainly by the high rates of comorbidity between certain disorders. This is precisely what we do with regards to externalizing disorders/problems. Our findings provide support for this new "dimensional" approach to psychiatric research by showing these disorder/problems share substantial variance as well as common risk factors and that they exist along a continuum in the general population."
The findings shed light on the cognitive deficits that could be targeted in order to potentially help treat comorbid cases (e.g. adolescents who have been diagnosed with both conduct disorder and substance use problems). "Comorbid cases are harder to treat and have worse prognosis than non-comorbid cases, and currently there are very few interventions or clinical strategies that are designed to treat comorbidity," Castellanos-Ryan said.
"Prevention and intervention approaches for externalizing problems – ADHD, conduct disorder and substance use – could benefit from incorporating training components that target the brain functions or deficits related to impulsive action, impulsive choice, and reward sensitivity.
Furthermore, these findings suggest that new intervention and prevention strategies targeting these deficits, either at the personality, cognitive or neural level, have the potential to concurrently impact on a number of clinical outcomes during adolescence and potentially before problems occur."
About the Study
Natalie Castellanos-Ryan, PhD, and Professor Patricia Conrod, PhD, are researchers affiliated with the University of Montreal's Department of Psychiatry and the Research Centre at the CHU Sainte-Justine Mother and Child Hospital Centre. Castellanos-Ryan is also affiliated with the university's School of Psychoeducation. The research team published "Neural and Cognitive Correlates of the Common and Specific Variance Across Externalizing Problems in Young Adolescence" in the American Journal of Psychiatry on July 30, 2014. The research was supported by the European Union-funded FP6 Integrated Project IMAGEN (Reinforcement- Related Behaviour in Normal Brain Function and Psychopathology; LSHM-CT- 2007-037286), the FP7 project IMAGEMEND (Imaging Genetics for Mental Disorders) and the Innovative Medicine Initiative Project EU-AIMS (115300-2), the Medical Research Council Programme Grant "Developmental Pathways Into Adolescent Substance Abuse" (93558), and the Swedish funding agency FORMAS. Further support was provided by the Bundesministerium für Bildung und Forschung (BMBF grants 01GS08152 and 01EV0711), the Deutsche Forschungsgemeinschaft (DFG) Reinhart-Koselleck Award (SP 383/5-1), and DFG grants SM80/5-2, SM 80/7-1, SFB 940/1. This research was also supported by the German Ministry of Education and Research (grant 01EV0711). Natalie Castellanos-Ryan's and Patricia Conrod's salaries are awarded from the Fonds de Recherche du Québec–Santé.
William Raillant-Clark | Eurek Alert!
New study: How stable is the West Antarctic Ice Sheet?
09.02.2016 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
Online shopping might not be as green as we thought
08.02.2016 | University of Delaware
Today, plants and microorganisms are heavily used for the production of medicinal products. The production of biopharmaceuticals in plants, also referred to as “Molecular Pharming”, represents a continuously growing field of plant biotechnology. Preferred host organisms include yeast and crop plants, such as maize and potato – plants with high demands. With the help of a special algal strain, the research team of Prof. Ralph Bock at the Max Planck Institute of Molecular Plant Physiology in Potsdam strives to develop a more efficient and resource-saving system for the production of medicines and vaccines. They tested its practicality by synthesizing a component of a potential AIDS vaccine.
The use of plants and microorganisms to produce pharmaceuticals is nothing new. In 1982, bacteria were genetically modified to produce human insulin, a drug...
Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock which attains an accuracy which had only been predicted theoretically so far. Their optical ytterbium clock achieved a relative systematic measurement uncertainty of 3 E-18. The results have been published in the current issue of the scientific journal "Physical Review Letters".
Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock...
The University of Würzburg has two new space projects in the pipeline which are concerned with the observation of planets and autonomous fault correction aboard satellites. The German Federal Ministry of Economic Affairs and Energy funds the projects with around 1.6 million euros.
Detecting tornadoes that sweep across Mars. Discovering meteors that fall to Earth. Investigating strange lightning that flashes from Earth's atmosphere into...
Physicists from Saarland University and the ESPCI in Paris have shown how liquids on solid surfaces can be made to slide over the surface a bit like a bobsleigh on ice. The key is to apply a coating at the boundary between the liquid and the surface that induces the liquid to slip. This results in an increase in the average flow velocity of the liquid and its throughput. This was demonstrated by studying the behaviour of droplets on surfaces with different coatings as they evolved into the equilibrium state. The results could prove useful in optimizing industrial processes, such as the extrusion of plastics.
The study has been published in the respected academic journal PNAS (Proceedings of the National Academy of Sciences of the United States of America).
Exceeding critical temperature limits in the Southern Ocean may cause the collapse of ice sheets and a sharp rise in sea levels
A future warming of the Southern Ocean caused by rising greenhouse gas concentrations in the atmosphere may severely disrupt the stability of the West...
12.02.2016 | Event News
09.02.2016 | Event News
02.02.2016 | Event News
12.02.2016 | Physics and Astronomy
12.02.2016 | Life Sciences
12.02.2016 | Medical Engineering