Theresa H. M. Moore, MSc, Research Associate in the Department of Social Medicine at the University of Bristol, and Stanley Zammit, PhD, MB, MA, Clinical Lecturer in the Department of Psychological Medicine at Cardiff University, wrote the following in their July 28, 2007 article titled "Cannabis Use and Risk of Psychotic or Affective Mental Health Outcomes: A Systematic Review," published in The Lancet:

“There was an increased risk of any psychotic outcome in individuals who had ever used cannabis…with greater risk in people who used cannabis most frequently. There is now sufficient evidence to warn young people that using cannabis could increase their risk of developing a psychotic illness later in life.”

July 28, 2007