Gyrification brain abnormalities associated with adolescence and early-adulthood cannabis use

Trabajo presentado a la 10ª Reunión anual de la Sociedad Española de Investigación sobre Cannabinoides celebrada en Santander del 26 al 28 de noviembre de 2009.-- et al.Although cannabis is the most widely used illicit drug in the world, the long-term effect of its use in the brain remains controversial. In order to determine whether adolescence and early-adulthood cannabis use is associated with gross volumetric and gyrification abnormalities in the brain, we set up a cross-sectional study using structural magnetic resonance imaging in a sample of general population subjects. Thirty cannabis-using subjects (mean age, 25.7 years; mean duration of regular use, 8.4 years, range: 3-21) with no history of polydrug use or neurologic/mental disorder and 53 non-using control subjects (mean age, 28.6 years) were included. Cannabis users had a 1.7% reduction in gray matter volume and a 31.3% increase in cortical cerebrospinal fluid (CCSF) volume in the right hemisphere; bilaterally decreased concavity of the sulci in the frontal, temporal and parietal lobes; and thinner sulci in the right frontal and parietal lobes. CCSF volume was significantly correlated with less concave sulci and more convex gyri. Among non-users, age was significantly correlated with decreased gyrification (i.e., less concave sulci and more convexe gyri) and decreased cortical thickness, supporting the notion of age-related gyrification changes. However, among cannabis users gyrification indices did not show significant dependency on age, age of regular cannabis use initiation, or cumulative exposure to cannabis. These results suggest that cannabis use in adolescence and early-adulthood might involve a premature alteration in cortical gyrification similar to what is normally observed at a later age, probably through disruption of normal neurodevelopment. However, further prospective longitudinal research is needed to examine the mechanisms of this long-term cannabis related harm and the possible recovery after abstinence.Peer Reviewe

Neuronal hyperactivity accelerates depletion of neural stem cells and impairs hippocampal neurogenesis

Adult hippocampal neurogenesis is believed to maintain a range of cognitive functions, many of which decline with age. We recently reported that radial neural stem cells (rNSCs) in the hippocampus undergo activation-dependent conversion into astrocytes, a mechanism that over time contributes to a reduction in the rNSC population. Here, we injected low and high levels of kainic acid (KA) in the dentate gyrus to assess whether neuronal hyperexcitation, a hallmark of epileptic disorders, could accelerate this conversion. At low levels of KA, generating epileptiform activity without seizures, we indeed found increased rNSC activation and conversion into astrocytes. At high levels, generating sustained epileptic seizures, however, we find that rNSCs divide symmetrically and that both mother and daughter cells convert into reactive astrocytes. Our results demonstrate that a threshold response for neuronal hyperexcitation provokes a dramatic shift in rNSC function, which impairs adult hippocampal neurogenesis in the long term.publisher: Elsevier articletitle: Neuronal Hyperactivity Accelerates Depletion of Neural Stem Cells and Impairs Hippocampal Neurogenesis journaltitle: Cell Stem Cell articlelink: http://dx.doi.org/10.1016/j.stem.2015.04.003 associatedlink: http://dx.doi.org/10.1016/j.stem.2015.04.011 content_type: article copyright: Copyright © 2015 Elsevier Inc. All rights reserved.status: publishe