This study aims to assess the rate of depressed patients (unipolar or bipolar) with basal plasma lithium levels above 0.1 µeq/L.~It also aims to :~compare basal plasma lithium levels according to the occurrence of a suicidal event in the year prior to inclusion ;~assess the association of lithium levels with the intensity of current suicidal ideation ;~assess the association of lithium levels with impulsiveness ;~assess the association of lithium levels with characteristics of bipolar disorder (for patients with bipolar disorder) ;~assess the association of lithium levels with emotional lability ;~assess, in the patients with a suicidal event in the year prior to the inclusion, the association of lithium levels with the characteristics of suicide attempts~To do so, 158 patients currently suffering from a major depressive disorder and who have not received any lithium treatment over the last year, will be included and divided in two groups :~Depressed patients with a history of suicidal event over the last 12 months (suicide attempters/ideations) ;~Depressed patients with no history of suicidal event over the last 12 months (affective controls).~Following a clinical assessment, a blood sample will be collected from each participant to measure basal plasma lithium levels.~Study participation will be done in one day.~The investigators expect :~an inverse association between lithium levels and suicidal events in patients~an inverse association between lithium levels and impulsiveness and aggression in patients This study will contribute to a better knowledge on suicidal behavior, especially by confirming the protective effect of lithium and improving the understanding of the mechanisms involved.~This knowledge will eventually make it possible to develop prevention and management strategies.~More appropriate prevention and management strategies better adapted to patients at risk of suicide.
Suicidal behavior is a major public health issue and there are currently no specific treatments for it.~However, lithium, the reference treatment for bipolar disorder, have been shown to be effective in preventing suicidal risk.~Apart from drug treatments, lithium is present in our environment and its levels varies from one individual to another, depending, especially, on diet.~Knowing that patients with a mood disorder generally have a poor lifestyle and a less rich and varied diet than the general population, variations in basal lithium levels can be expected in these patients.