Major depressive disorder (MDD) is characterized by a very heterogeneous course and by a significant suffering and loss of functionality for people who develop it. The main objective of this thesis is to identify those brain structures that could be altered in first depressive episodes (FED) for their characterization as markers of the disorder and those structures that will predict or will show alterations while recurrences appear. To do this, the habenula was studied from a structural transversal neuroimaging approach to find potential differences between patients at different stages of depression and healthy controls. Subsequently, a longitudinal study of FED patients using voxel-based morphometry (VBM) has been carried out to identify which structures could be are altered in early stages of MDD and to identify if they are related to the appearance of recurrences. The first article included 95 patients in different stages of depression i. e. , FED, remitted-recurrent and chronic refractory depression patients and healthy controls (HC). The results showed that habenula white matter volume (WMV) was significantly higher in women-FED compared to those who suffered from chronic depression and with healthy control patients. Among the women, it is observed that greater habenular WMV correlate with elderly onset and shorter duration of the disease, although this result could not be confirmed in the analysis by groups. The second article has a sample of 33 FED and 33 HC that have been followed for two years. FED patients present lower WMV in the superior right frontal gyrus and in the anterior corona radiata than the healthy controls at baseline, although these differences seem to vanish during the follow-up. Longitudinal analysis showed that FED patients who suffered recurrences (n = 15) have enlarged WMV in left posterior corona radiata and right posterior thalamic radiation at the end of the follow-up. By contrasts, no differences in gray matter volume were observed between groups either at baseline nor at follow-up. In conclusion, the first study suggests that habenula's WMV is altered in the first stages of major depression and stands up for a putative preferential contribution of white matter over grey matter changes within this structure associated with early stages of MDD, particularly in women. Habenular WMV could translate those neuroplastic changes that occur during early remission. The second study supports the presence of prefrontal WM alterations in the early stages of depression. The disappearance of these alterations suggests that they are a state marker therefore, they may remit after an early intervention. WMV increases in posterior regions in recurrent FED patients could translate a compensatory effect of the brain, more specific for the white matter, to cope with the disease in the earliest phases.
Alteraciones cerebrales en la depresión mayor como factores predictores del curso de la enfermedad : hallazgos transversales y longitudinales en la sustancia blanca de pacientes con un primer episodio depresivo
Carceller Sindreu, M. D. M. (Author). 24 May 2019
Student thesis: Doctoral thesis
Student thesis: Doctoral thesis