Natalia Elizalde PHOTO: Manuel Castells.

Natalia Elizalde from Pamplona has identified some neurobiological mechanisms that could be involved in chronic depression and in the vulnerability of some patients to relapse. This study is part of her doctoral thesis , elaborated at the School of Pharmacy and Human Nutrition and Dietetics of the University of Navarra and directed by Rosa Tordera, professor of Pharmacology at department .

According to the new doctor, while in the first depressive episodes the cause-effect relationship with stressful events is clearer, relapses appear more spontaneously: "This leads us to think that chronic depression or the different relapses are independent of the traumatic events and other neurobiological processes such as those we have found begin to appear and dominate".

Among them, the researcher highlights the alteration in the activity of serotonin neurons in the brainstem, "a problem that is completely corrected after antidepressant treatment". Likewise, the neurotrophic factor BDNF in the hippocampus decreases, a fact that could be related to the neuronal atrophy that is sometimes observed in the post-mortem tissue of depressed patients.

"In addition, in terms of neurotransmitter levels, we have found that the decrease in GABA in the ventral hippocampus is not resolved after antidepressant treatment, something that would influence the vulnerability to relapse that many people suffer," he stresses. The study also points out that chronic stress causes alterations in the expression of genes involved in neuronal plasticity, at the same time as it decreases cell proliferation and the birth of new neurons.

Twice as many women as men
As the researcher explains, depression is the most diagnosed psychiatric disease in developed countries, where it affects -in the case of Europe- 5% (acute cases) and 10% (milder cases) of the population. "Overall," adds the new doctor of Pharmacy from the University of Navarra, "the incidence in women is twice that of men, and its prevalence varies according to age. Here it is worth highlighting the increase in cases in young people between 15 and 24 years of age, due, among other causes, to situations of stress, anxiety, hyperactivity or attention deficit".

In relation to stress and depression, Natalia Elizalde clarifies that although they are related problems, both follow a different time course, "since depressive disorders, once initiated, last for months and even years, beyond the exhibition to the event that originated them. Hence, the seriousness of the disease lies not so much in the ineffectiveness of the treatments as in the high probability that it will become a chronic and recurrent ailment".

In this regard, the researcher recalls that the widely used antidepressants that increase serotonin and/or noradrenaline levels - fluoxetine (Prozac), paroxetine, citalopram or venlafaxine - "only partially palliate this damage, which is why it is so important to develop drugs that restore the functioning of the system, to which this study could contribute".