2.1. Subjects
Six cannabis users and 7 control subjects were recruited at the
IMIM-Hospital del Mar Research Institute (Barcelona, Spain). The study
was reviewed and approved by the local institutional ethics committee
(CEIC-PSMAR). All subjects provided their written informed consent after
the study and procedures were explained to them in full. All the
subjects, of either sex, were between 18 and 40 years old, and the
cannabis users consumed 5 or more cannabis cigarettes per week. Subjects
were instructed to abstain from cannabis use for at least 12 h before
testing. The subjects were excluded if they fulfilled any of the
following criteria: (1) comply with the criteria for any severe mental
disorder according to DSM-V; (2) any history of severe congenital,
medical or neurological illness; (3) a history of severe mental illness
among first degree relatives; (4) consumption of other drugs of abuse
except alcohol and tobacco; and (5) present any medical condition with
nasal repercussions (rhinitis or bleeding). The consumption of cannabis
was verified by testing for tetrahidrocannabinol (THC) metabolites in
urine (Instant-View, Multipanel 10 Test Drug Screen: Alfa Scientific
Designs, USA). The exclusion criteria were verified using the Hamilton
Depression Rating Scale (HDRS-17), the individual’s clinical history and
a diagnostic interview according to DSM-V criteria (SCID). Furthermore,
a Neurological Evaluation Scale was used to evaluate neurological soft
signs (NSS (Buchanan et al., 1989) and the Global Assessment of
Functioning scale (GAF) was used to measure the level of functionality
(Endicott et al., 1976).