Gender Identity Disorder (GID) is characterized by a strong and persistent cross-gender identification that affects different aspects of behavior. Brain-derived neurotrophic factor (BDNF) plays a critical role in neurodevelopment and neuroplasticity. Altered BDNF-signaling is thought to contribute to the pathogenesis of psychiatric disordersand is related to traumatic life events. To examine serum BDNF levels, we compared one group of DSM-IV GID patients (n = 45) and one healthy control group (n = 66). Serum BDNF levels were significantly decreased in GID patients (p = 0.013). This data support the hypothesis that the reduction found in serum BDNF levels in GID patients may be related to the psychological abuse that transsexuals are exposed during their life.
Gender Identity Disorder (GID) is characterized by a strong and persistent cross-gender identification that affects different aspects of behavior(WHO, 1992; APA, 2000). The individuals experience gender dysphoria and desire to live and be accepted as a member of the opposite sex (Dhejne et al., 2011). It is a highly disabling disorder, characterized by intense psychological suffering (Lobato et al., 2006). The recommended treatment may be provided by a multidisciplinary team with physical and psychological assistance, hormone therapy and sex reassignment surgery (Lobato et al., 2006; Salvador et al., 2012). GID is a rare condition, with an estimated worldwide lifetime prevalence ranging 0.001–0.002% (Hoshiai et al., 2010).
The pathophysiology and etiopathogenesis of GID have not been fully elucidated (Selvaggi and Bellringer, 2011). Most of the current hypotheses on the possible cause of transsexuality presume a combination of a genetic background and an early organizational effect on the interaction of sex hormones with the developing brain during critical fetal periods (Garcia-Falgueras and Swaab, 2008). Results from a Dutch research group have showed a neurological basis for gender identity with sexual morphological differentiation of the brain (Garcia-Falgueras and Swaab, 2008; Kruijver et al., 2000; Selvaggi and Bellringer, 2011; Swaab et al., 2002; Zhou et al., 1995).
Lifetime psychiatric comorbidity in GID patients is high, and this should be taken into account in their assessment and treatment planning (Hoshiai et al., 2010). For most GID patients, a strong and persistent identification with the opposite sex and discomfort with one’s own sex is a life challenge that often creates distress and carries potential stigmatization (Hoshiai et al., 2010; Matsumoto et al., 2009). Moreover, it was reported that children with GID are at high risk for developing psychiatric problems (Wallien, 2007). Kersting et al. (2003) found a high prevalence of childhood trauma, especially emotional abuse and emotional neglect, in the transsexual sample (Kersting et al., 2003).
Brain-derived neurotrophic factor (BDNF) is a member of the growth factor family, involved in synaptic plasticity, neurogenesis, neuronal survival and normal maturation of neuronal developmental pathways (Fernandes et al., 2009; Gama et al., 2007; Grande et al., 2010) BDNF has a widely reported relation with corticosteroids that appear to play a key role in the environmentally mediated vulnerability to psychopathology (Grande et al., 2010). Besides, BDNF serum levels have been associated with traumatic life events and psychiatric disorders (Boulle et al., 2012; Kauer-Sant'Anna et al., 2007).
Given the evidence that GID patients suffer from chronic stress (Kersting et al., 2003; Matsumoto et al., 2009) and that chronic stress and psychiatric disorders are related to a decrease on BDNF levels (Kauer-Sant'Anna et al., 2007), we compared serum BDNF levels in a group of GID patients and a group of healthy controls. The aim of the present study, therefore, was to evaluate whether GID patients have lower BDNF levels than controls.
