Genetic influences on alexithymia and their relationship with depressive symptoms

• Published in: Journal of psychosomatic research Vol. 71; no. 4; pp. 256 - 263
• Main Authors: Picardi, Angelo, Fagnani, Corrado, Gigantesco, Antonella, Toccaceli, Virgilia, Lega, Ilaria, Stazi, Maria Antonietta
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.10.2011; Elsevier
• Subjects: Adult and adolescent clinical studies; Affective Symptoms - genetics; Alexithymia; Behavioral genetics; Biological and medical sciences; Depression; Depression - genetics; Environmental aspects; Female; Genetic factors; Humans; Individual differences; Male; Medical sciences; Mood disorders; Personality Inventory; Psychiatric Status Rating Scales; Psychiatry; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Registries; Social Environment; Twins; Twins - genetics; Twins - psychology; Young Adult; Depression; Twins; Behavioral genetics; Alexithymia; Mood disorder; Symptomatology; Genetics; Personality; Behavior; Genetic determinism; Twin
• ISSN: 0022-3999; 1879-1360
• DOI: 10.1016/j.jpsychores.2011.02.016

Abstract Objective The factors involved in the etiology of alexithymia are still unclear. While a few studies suggested substantial genetic influences on alexithymia, it remains to be determined if these influences are independent of genetic influences on other mental health variables correlated with alexithymia, such as depression. This study is aimed at confirming previous findings of a genetic contribution to alexithymia, examining whether there are genetic or environmental influences common to alexithymia facets, and investigating whether genetic influences on alexithymia are independent of genetic influences on depression. Methods The 20-item Toronto Alexithymia Scale and a validated measure of depression were administered to a sample of 729 twins (45% males) aged 23–24 years drawn from the population-based Italian Twin Register. Genetic structural equation modeling was performed with the Mx program. Results Genetic factors accounted for 42% of individual differences in alexithymia. Unshared environmental factors explained the remaining proportion of variance. There was a substantial (0.65) genetic correlation between alexithymia and depression. The inclusion of depression as a covariate in the genetic models reduced the heritability estimate for alexithymia to 33%. Conclusions Despite some limitations, this study corroborates the notion that genetic factors contribute substantially to individual differences in alexithymia, with unshared environmental factors also playing an important role. Also, it suggests a genetic link between alexithymia and depression.