article_snippet: Marijuana now contains increasingly high concentrations of tetrahydrocannabinol (THC), the psychoactive compound which gives the 'high'.
article_snippet: But concentrations of cannabidiol (CBD), a lesser known compound that is being investigated for its medical proponents, but does not create a 'high', has gone down.
article_snippet: The research was carried out by Dr Andy LaFrate, the president and director of research of Charas Scientific, a lab in Colorado, US, which carries out potency testing on marijuana samples on the market today.
article_snippet: The average potencies of the samples Andy LaFrate analysed was 20 per cent THC, but Andy LaFrate saw  values close to 30 per cent, which Andy LaFrate described as'huge'.
article_snippet: Andy LaFrate explained that 30 years ago, THC levels in marijuana were well below 10 per cent.
article_snippet: Researchers are currently investigating CBD as a treatment for schizophrenia, Huntington's disease and Alzheimer's disease, as well as anxiety and depression.
article_snippet: But unlike THC, CBD doesn't get provide the same 'high', which is why THC could be considered in treatments for children.
article_snippet: Extra potent: Concentrations of marijuana's active ingredient tetrahydrocannabinol (THC) (pictured) have increased from less than 10 per cent in samples from the 1980s to up to 30 per cent in samples tested today .
article_snippet: Dr LaFrate said: 'One thing that's been surprising is the level of microbial contamination in marijuana.' 'Many of the samples were covered in fungi or bacterial contaminants. '
highlights_snippet: scientists analysed levels of tetrahydrocannabinol (THC) in marijuana .
  
highlights_snippet: Found THC concentrations of 30%, compared to 10% three decades ago .
  