The present invention relates to the use of cannabidiolic acid (CBDA) 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). CBDA has been shown to be particularly effective in improving cognitive dysfunction in rodent models of ASD, FXS, RS and AS. The CBDA is preferably substantially pure. It may take the form of a highly purified extract of cannabis such that the CBDA is present at greater than 95% of the total extract (w/w) and the other components of the extract are characterised. Alternatively, the CBDA is synthetically produced.
