Alexithymia is a personality construct first identified in hospitalized psychosomatic patients. It is characterized by difficulties in identifying (DIF) and describing (DDF) feelings, an externally oriented, or concrete and pragmatic thinking style (EOT), as well as a scarcity of fantasy and imagination. Alexithymia has been associated with increased psychiatric and somatic morbidity across diagnostic categories, as well as increased markers of physiological stress. The etiology of alexithymia is unclear although childhood environmental influences are likely to play a role in it. Several studies imply that alexithymia is a heterogeneous phenomenon with possible subtypes that have differential associations with mental health and emotion regulation. This dissertation is part of the FinnBrain Birth Cohort Study, in which we analyzed a large sample of fathers and mothers and compared their alexithymic traits with mental and physical health outcomes, as well as self-reported early-life adversities in childhood.

Our results support the hypotheses of the existence of two alexithymia subtypes: One characterized by high levels of DIF, as well as increased depressive and anxiety symptoms; and another characterized by high levels of EOT, exhibiting lower psychiatric symptomatology. However, EOT, even while not increasing the risk for mood or anxiety symptoms, was associated with increased substance use in men, and a higher BMI and higher prevalence of gestational diabetes in women. In pregnant women, alexithymic traits, and especially the dimension of DIF, was additionally associated with higher hair cortisol concentrations during late pregnancy, indicating heightened levels of chronic stress. Regarding early-life adversity, we showed that alexithymia was specifically related to childhood experiences of emotional neglect and was associated with adult attachment insecurity.

These findings show that alexithymic traits have differential associations with psychiatric symptomatology, substance use and metabolic health. Importantly, they show that many of these associations are independent of mood and anxiety. Findings on early-life adversity in alexithymia imply that depression with concurrent alexithymia may represent a specific subtype of depression, treatment of which may benefit from a focus on childhood emotional neglect and attachment insecurity.