Table 4 Summary of the regression of the variable “total score in PANSS” (R² = 0.82; F = 7.03; p = 0.000)

Smoked cannabis alone

0.53

0.06

5.09

0.000

Tobacco consumption

0.80

0.23

6.13

0.000

Frequency of tobacco use

0.42

0.12

3.43

0.001

Age of onset of cannabis use

− 0.91

0.15

− 4.74

0.000

Often smoked cannabis alone

0.91

0.39

7.20

0.000

Perception of risk related to tobacco and cannabis use

0.15

0.21

2.13

0.039

Representations of the unpleasant psychological effects and physical risks of cannabis

− 0.32

0.65

− 3.85

0.000

Representations of positive school effects of cannabis

0.37

0.19

2.53

0.016

Representations of dependency

0.47

0.72

5.31

0.000

Cannabis dependence

− 0.45

0.09

− 3.59

0.001