While the association between adult
Attention Deficit/Hyperactivity Disorder (A-
ADHD) and
Substance Use Disorders (SUDs) has been widely explored, less attention has been dedicated to the various
substance use variants. In a previous paper, we identified two variants: type 1 (use of stimulants/alcohol) and type 2 (use of
cannabinoids). In this study, we compared demographic, clinical and symptomatologic features between Dual Disorder A-
ADHD (DD/A-
ADHD) patients according to our
substance use typology, and A-
ADHD without DD (NDD/A-
ADHD) ones. NDD patients were more frequently diagnosed as belonging to inattentive
ADHD subtype compared with type 1 DD/A-
ADHD patients, but not with respect to type 2 DD/
ADHD. NDD/A-
ADHD patients showed less severe symptoms of hyperactivity/impulsivity than DD/A-
ADHD type 1, but not type 2. Type 1 and type 2 patients shared the feature of displaying higher impulsiveness than NDD/A-
ADHD ones. General psychopathology scores were more severe in type 2 DD/
ADHD patients, whereas type 1 patients showed greater similarity to NDD/A-
ADHD. Legal problems were more strongly represented in type 1 than in type 2 patients or NDD/A-
ADHD ones. Our results suggest that type 1 and type 2
substance use differ in their effects on A-
ADHD patients-an outcome that brings with it different likely implications in dealing with the diagnostic and therapeutic processes.