Alexithymia is a multidimensional psychiatric construct indicating impaired emotional awareness. Its main features are (i) difficulties in identifying feelings and distinguishing them from bodily sensations, (ii) difficulties describing feelings to others, (iii) an externally oriented style of thinking, and (iv) a poor imaginal capacity. Alexithymia attracts great attention among practitioners and researchers in the clinical field because it has the potential to unveil the emotional disturbances occurring in several mental and physical diseases. As has recently been shown, most of these diseases are not only characterized by an altered perception of emotional states but, more generally, by an altered perception of internal bodily states, namely an altered interoceptive awareness. Consequently, a large body of research has focused on the interplay between alexithymia and interoceptive deficits. Yet, the extent of their association is to date unclear. This question is coupled with a further one concerning whether all or just a few features of alexithymia have clinical relevance and/or an association with interoceptive deficits. Indeed, differences in interoceptive ability are not the only candidate to explain differences in emotional awareness. Rather, the sociocultural environment the individual is surrounded by might play a role at least in the way emotions are expressed, but also in the way emotions are felt. This thesis considers both the mentioned issues, thus addressing the relationship that alexithymia entertains with interoceptive abilities on the one hand and with sociocultural factors on the other. I call these, respectively, the embodied and the embedded aspects of alexithymia. This manuscript is articulated in four parts. Part I introduces alexithymia and shows how the operationalization of the construct through time has facilitated the broadening of its conceptual nucleus. Part II focuses on the embodied aspect of alexithymia, namely its relationship with interoceptive deficits. This section outlines results from two empirical studies testing the association between alexithymia and self-reported interoceptive awareness across three large nationality samples. Part III examines the embedded aspect of alexithymia, namely its relationship with sociocultural factors. Together these studies show that (1) interoceptive deficits are a core component of alexithymia, although the latter cannot be reduced to the former, and (2) differences in externally–oriented thinking are empirically predicted by sociocultural factors more than by self-reported interoceptive awareness, even within the same ethnocultural group. In the fourth and last part, a general discussion summarizes the contribution of this work, raising criticisms regarding the current operationalization of alexithymia and the misunderstandings it can cause, especially when combined with a fallacious interpretation of nosological categories. The thesis concludes with the suggestion that adopting a stricter conception of alexithymia and analyzing the interplay between its interoceptive and cognitive subcomponents is beneficial for both emotion theory and clinical practice.

Objective: Previous studies have established an association between number of traumatic experiences and alexithymia. The present study examines this relationship in a large-scale representative sample of the German general population (N=2,507) and explores the potential mediating effects of posttraumatic symptomatology, particularly avoidance/numbing. Methods: Alexithymia was assessed with the German version of the Toronto Alexithymia Scale (TAS-20). Posttraumatic symptomatology was operationalized by the symptom score of the modified German version of the Posttraumatic Symptom Scale, and traumatic experiences were assessed with the trauma list of the Munich Composite International Diagnostic Interview. Two mediation analyses were conducted. Results: Of the total sample, 24.2% (n=606) reported at least one traumatic experience, 10.6% (n=258) were classified as alexithymic, and 2.4% (n=59) fulfilled the criteria of posttraumatic stress disorder (PTSD). Participants who had survived five or more traumatic experiences had significantly higher alexithymia sum scores. The PTSD symptom cluster avoidance/numbing mediated the association between the number of traumatic experiences and alexithymia. Conclusions: Our findings illustrate an association between number of traumatic experiences and alexithymia and the influence of emotional avoidance and numbing within this relationship. The significant relationship between alexithymia and number of traumatic experiences in a general population sample further supports the concept of multiple and complex traumatization as associated with alexithymia. The results suggest the importance of further investigations determining the causal impact of alexithymia both as a potential premorbid trait and as consequence of traumatization. Lastly, future investigations are needed to clarify alexithymia as a distinct trauma-relevant characteristic for better diagnostics and specialized trauma-integrative therapy.

Objective: Previous studies have established an association between number of traumatic experiences and alexithymia. The present study examines this relationship in a large-scale representative sample of the German general population (N=2,507) and explores the potential mediating effects of posttraumatic symptomatology, particularly avoidance/numbing. Methods: Alexithymia was assessed with the German version of the Toronto Alexithymia Scale (TAS-20). Posttraumatic symptomatology was operationalized by the symptom score of the modified German version of the Posttraumatic Symptom Scale, and traumatic experiences were assessed with the trauma list of the Munich Composite International Diagnostic Interview. Two mediation analyses were conducted. Results: Of the total sample, 24.2% (n=606) reported at least one traumatic experience, 10.6% (n=258) were classified as alexithymic, and 2.4% (n=59) fulfilled the criteria of posttraumatic stress disorder (PTSD). Participants who had survived five or more traumatic experiences had significantly higher alexithymia sum scores. The PTSD symptom cluster avoidance/numbing mediated the association between the number of traumatic experiences and alexithymia. Conclusions: Our findings illustrate an association between number of traumatic experiences and alexithymia and the influence of emotional avoidance and numbing within this relationship. The significant relationship between alexithymia and number of traumatic experiences in a general population sample further supports the concept of multiple and complex traumatization as associated with alexithymia. The results suggest the importance of further investigations determining the causal impact of alexithymia both as a potential premorbid trait and as consequence of traumatization. Lastly, future investigations are needed to clarify alexithymia as a distinct trauma-relevant characteristic for better diagnostics and specialized trauma-integrative therapy.

Abstract Somatization is a widespread phenomenon causing subjective suffering and disability. The aim of the study was to assess somatization disorder (SD) and somatization symptoms among young adult population and their associations with sociodemographic factors, alexithymia and temperament as well as psychiatric comorbidity. Various suggestions have been presented to operationalize somatization but none of them has been shown to be superior to others. In this study two definitions were used: SD by DSM-III-R classification diagnostic criteria and "somatization" meaning four or more symptoms of the 35 symptoms of DSM-III-R SD criteria. The study population was a subsample of the Northern Finland Birth Cohort 1966 (NFBC 1966), consisting of cohort members living in Oulu (N = 1,609) on January 1st 1997. The NFBC 1966 is a general population birth cohort of 12,058 live-born children covering 96.3% of all deliveries in the catchment area. The best-estimated procedure was used for assessment of psychiatric morbidity including SD and somatization. Data were collected from the Finnish Hospital Discharge Register and from all available outpatient and inpatient records. Data on education were gathered from Statistics Finland. Other sociodemographic variables, alexithymia and temperament scores were drawn from questionnaires of the field study conducted in 1997 and from earlier follow-up studies. The prevalence of SD was 1.1% (N = 18). Of the subjects 6.1% (N = 97) had somatization. The female-to-male ratio was 5:1 and 6:1, respectively. SD was not recognized by any of the treating physicians, at least not documented in case notes. The observed occurrences of SD and somatization were at a level comparable with earlier international population studies. Somatization did not associate with depression or alexithymia, and neither could a characteristic temperament profile be recognized. Somatization was associated with psychological distress. These results indicate a need for training physicians to recognize SD and somatization and its comorbidity. This will have implications both for psychiatry and other medical specialties regarding collaboration and underlines the importance of liaison-psychiatry at general hospitals. The results suggest a need for more studies about the etiology and development of SD and somatization. / Tiivistelmä Somatisaatio on yleinen ilmiö, josta aiheutuu subjektiivista kärsimystä ja toimintakyvyn laskua. Tämän tutkimuksen tarkoitus oli arvioida somatisaatiohäiriön ja somatisaatio-oireilun yleisyyttä nuorilla aikuisilla sekä näiden ilmiöiden yhteyttä sosiodemografisiin tekijöihin, aleksitymiaan, temperamenttiin ja psykiatriseen sairastavuuteen. Somatisaation käsitteellistämiseksi on esitetty useita vaihtoehtoja mutta mikään niistä ei ole osoittautunut muita paremmaksi. Tässä tutkimuksessa käytetiin kahta määritelmää: DSM-III-R -diagnoosiluokituksen mukaista somatisaatiohäiriön diagnoosia tai somatisaatio-oireilua, jossa esiintyy neljä tai useampia DSM-III-R:n 35 somatisaatiohäiriön oireesta. Tutkimusaineiston muodostivat Pohjois-Suomen vuoden 1966 syntymäkohortin ne jäsenet, jotka asuivat Oulussa 1. tammikuuta 1997 (N =  1,609). Alkuperäinen kohortti koostuu 12,058 elävänä syntyneestä tutkittavasta, mikä kattaa 96.3 % kaikista synnytyksistä Pohjois-Suomessa. Niin kutsutun best-estimated -menettelyn avulla arvioitiin tutkittavien psykiatrista sairastavuutta mukaan lukien somatisaatiohäiriö ja -oireilu. Tietoa kerättiin sairaaloiden poistoilmoitusrekisteristä. Avohoidon sairauskertomustieto koottiin kattavasti. Koulutusasteesta saatiin tieto Tilastokeskukselta. Muita sosiodemografisia tekijöitä, aleksitymiaa ja temperamenttia arvioitiin vuoden 1997 kenttätutkimuksen ja aiempien seurantatutkimusten tietojen avulla. Somatisaatiohäiriön esiintyvyys oli 1.1 % (N =  18). Somatisaatio-oireita todettiin 6.1 % (N =  97) tutkittavista. Naisten osuus oli somatisaatiohäiriössä 5:1 ja somatisaatio-oireilussa 6:1. Osoittautui, että lääkärit eivät tunnistaneet somatisaatiohäiriötä, ainakaan sitä ei oltu kirjattu sairauskertomuksiin. Havaitut somatisaatiohäiriön ja -oireilun esiintyvyydet ovat sopusoinnussa aiempien kansainvälisten tutkimusten kanssa. Somatisaatio-oireilu ei liittynyt masennukseen tai aleksitymiaan eikä somatisaatio-oireilusta kärsiville tutkittavilla todettu tyypillistä temperamenttiprofiilia. Somatisaatio liittyi psyykkiseen stressiin. Johtopäätöksenä voidaan todeta, että lääkäreille tulisi tarjota koulutusta somatisaatiohäiriön ja -oireilun tunnistamisessa. On tärkeää tunnistaa somatisaatio ja siihen liittyvä oheissairastavuus. Havainnot korostavat yleissairaaloiden yhteistyöpsykiatrian ja muiden erikoisalojen yhteistyön merkitystä somatisaatiosta kärsivien potilaiden tutkimuksessa ja hoidossa. Somatisaatiohäiriön ja -oireilun etiologian ja kehittymisen selvittämiseksi tarvitaan uusia tutkimuksia.