Ricerc@Sapienza

Over the last five decades, a number of biological oriented personality theories have been proposed
to explain how anatomical and functional differences in the human brain are responsible for
individual differences in personality. Catechol-O-methyltransferase (COMT) gene for the Val158Met
single nucleotide polymorphism (rs4680) is known to influence the activity of the enzyme responsible
for dopamine metabolism and has been linked with various aspect of personality dimensions and
cognitive processes. In the present study, non-clinical participants (201 women and 53 men) were
administered the Temperament and Character Inventory-Revised, Tellegen Absorption Scale,
Differential Attentional Processes Inventory, and Waterloo-Stanford Group Scale of Hypnotic
Suggestibility, Form C. Among these participants, COMT polymorphism (parameterized as a 3-level
variable: 0 = Met/Met, 1 = Val/Met, 2 = Val/Val) was assessed in 117 women and 51 men. Hypnotic
Suggestibility scores were significantly correlated with scores from the Absorption, Extremely
Focused Attention, and Dual Attention for Physical-Cognitive task. We failed to find the expected
significant association between COMT and Hypnotic Suggestibility scores. In contrast, COMT scores
were significantly correlated with scores from Novelty Seeking (r = -.15, p = .049) and its
Disorderliness subscale (r = -.21, p = .006). A principal component analysis (with varimax rotation),
performed on personality and attention measures, yielded a four-factor solution: Factor-1 (Moderately
Focused Attention, Dual Attention Cognitive-Cognitive, and Dual Attention Physical-Cognitive),
Factor-2 (Novelty Seeking, Reward Dependence, and Harm Avoidance), Factor-3 (Hypnotic
Suggestibility, Absorption, and Extremely Focused Attention), and Factor-4 (Persistence). These
factors accounted for 18.4%, 16.3%, 16.2%, and 12.3% of the total variance, respectively. These
findings guided us in the choice of the COMT, Persistence, Extremely Focused Attention, and
Absorption scores as predictors of Disorderliness scores in separate multivariate regression
analyses. Lower COMT activity, higher Absorption scores, and lower Persistence scores accounted
for 18% of the total variance in the whole sample, and 10.8% in female sample. In male sample,
higher Absorption and lower Persistence scores significantly predicted Disorderliness scores that
accounted for 7.4% of the total variance. Since our male sample was relatively small, further research
is needed to understand gender differences, if any, using a larger male sample.