The use of cannabidivarin (CBDV) in the treatment of autism spectrum disorder (ASD) and ASD-associated disorders such as Fragile X syndrome (FXS)； Rett syndrome (RS)； or Angelman syndrome (AS). The second invention disclosed relates to the use of CBDV in the treatment of schizophrenia and the third is related to the treatment of cognitive dysfunction. In some instances, the CBDV is preferably substantially pure. It may take the form of a highly purified extract of cannabis such that the CBDV is present at greater than 95% of the total extract (w/w) and the other components of the extract are characterised. Alternatively, the CBDV is synthetically produced. In some instances the CBDV is administered with one or more concomitant medications, such as an anti-epileptic drug.
