Researchers assessed 817 youth (aged 12 to 21) who previously participated in the National Consortium on Alcohol and Neurodevelopment in Adolescence study. They found that 123 subjects (15.2%) had used cannabis in the past year, and that cannabis use impaired inhibitory control, emotional control, and task planning.

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Adolescent Executive Dysfunction in Daily Life- Relationships to Risks, Brain Structure and Substance UseDownload
This paper is also stored here: http://bit.ly/2L0aMWa inside the CED Foundation Archive