What is depression ?
There are several categories of mood disorders (unipolar, bipolar, seasonal depression…) that are characterized by the appearance and recurrence of Major Depressive Episodes” (MDE).
A major depressive episode is not a reactionary sadness or a state of malaise, but is characterized by the presence of five of nine symptoms (sad mood, anhedonia, weight loss or gain, sleep disorders, feelings of guilt, etc.) persisting for at least two weeks, and by a change in the patient’s daily life compared to his or her previous situation.
None of these symptoms can be explained by grief or attributable to the direct physiological effects of a drug or other medical condition. The symptoms are accompanied by suffering felt by the subject or by those around him/her, and by an alteration in social and professional functioning.
The diagnosis of a major depressive episode is clinical and therefore subjective, insofar as there is currently no known biological test to confirm it. Diagnostic tools (standard questionnaires) have been developed to try to reduce this subjectivity in the field of research.
The etiology of these disorders is poorly understood, although the interaction of several biological factors (including genetic predisposition) and environmental factors (stress, emotional deprivation, abuse, etc.) is suspected.
According to the World Health Organization :
✔ The prevalence of depression is 5-10% of the population,
✔ 8-20% of the population will experience it in their lifetime,
✔ There is no ethnic or racial influence on the prevalence of depression
✔ 15% to 20% of patients with mood disorders attempt suicide
✔ Up to 50% of chronic sick leave is due to depression and anxiety
✔ depression is the world’s leading cause of disability
The different treatments for depression
The primary treatments for major depressive episodes are antidepressant drugs and psychotherapy.
The treatment of depression is primarily based on medication. There are several types of antidepressants with different mechanisms of action, which offers doctors several therapeutic possibilities (monotherapies, dual therapies, etc.). At least three weeks of treatment are necessary before a thymic improvement appears.
Drug treatments are effective in 60% to 70% of cases. In the other cases, the term “drug resistance” is used.
The psychotherapies used are of several types (psychodynamic therapies, cognitive and behavioural therapies, etc.) and vary greatly in duration (from several weeks to several years). They are effective after several weeks and require the active participation of the patient, which sometimes makes them unsuitable for the acute phases of the depressive episode, particularly in the case of melancholic states.
They are mainly used in the long term, generally as a complement to other treatments, and to prevent recurrence.
- Electroconvulsive therapy
Electroconvulsive therapy (ECT) (formerly seismotherapy) involves inducing an epileptic seizure by delivering a weak and very brief electric current through electrodes applied to the skull. It is performed under general anaesthesia. It is more effective than antidepressants and is also faster. It is used to treat the most severe depression, drug-resistant depression, or when other treatments are contraindicated.
Transcranial Magnetic Stimulation
Transcranial Magnetic Stimulation has proven its effectiveness in the treatment of depression. It is now recommended by learned societies and covered by the health systems of several industrialised countries (Germany, Netherlands, United States, Canada, Australia, New Zealand, Israel, etc.).
- How does a Transcranial Magnetic Stimulation (TMS) treatment work?
Treatment of depression with Transcranial Magnetic Stimulation (TMS) generally consists of daily sessions of about 20 minutes repeated over a period of 3 to 6 weeks. As TMS is minimally invasive, these sessions are often carried out on an outpatient basis. These repeated stimulations will lead to the modulation of the neuronal activity of a brain network involved in mood regulation.
The brain area stimulated in the first instance, belonging to a region of the brain called the dorsolateral prefrontal cortex (or DPLFC), is located at the junction of Brodman’s areas 9 and 46. The Syneika One neuronavigator precisely defines this target according to the patient’s brain anatomy, and guides the manipulator to accurately position the TMS coil.
This target will be stimulated at “high frequency” (usually 10 Hz) in case of stimulation on the left hemisphere, or at “low frequency” (1Hz) in case of stimulation on the right hemisphere.
The optimisation of the expected therapeutic effect of rTMS requires rigorous control, over the course of the sessions, of the procedure for locating the stimulation probe in relation to the target cortical area.
This control is carried out by the Syneika One neuronavigator.
- Effectiveness of Transcranial Magnetic Stimulation TMS
The expected result at the end of the first weeks of stimulation is a positive response for one patient out of two (50% reduction in score on a Hamilton scale) and remission for 20% of patients (HDRS<8)
If the symptoms do not improve sufficiently, the doctor may first suggest moving on to the target in the opposite hemisphere, the orbitofrontal cortex.
- What are the side effects of Transcranial Magnetic Stimulation ?
The most common side effects of TMS in the treatment of depression are headaches or discomfort at the stimulation site, experienced by a third of patients, especially during the first sessions. These side effects generally disappear spontaneously after the session.