Hyperdopaminergia has been identified at impulsive or psychotic patients, the polymorphism of COMT or other enzymes that metabolize dopamine could be involved. The deficiencies of the serotoninergic system in suicidal behaviour has been mentioned by many studies that indicate the reduction of 5-HT, 5-HIAA in CSF or 5-HTT polymorphism. Young patients with psychotic or depression symptoms manifest, frequently, aggressive and self-harm behaviour. Besides the association between the young age and the aggressivity of the patients with serious mental disorders, our study shows gender differences and this matter is sustained by hormonal factors. The study was conducted at the Gheorghe Preda Psychiatric Hospital in Sibiu. The study comprises 52 patients aged between 18 and 35 who were diagnosed with the diagnosis of Schizophrenia, Bipolar Affective Disorder, Depressive Episode and Major depressive disorder according to the DSM-5 criteria. Evaluation of the severity of psychiatric and depressive symptomathology were assessed with Brief Psychiatric Rating Scale and Beck Depression Inventory; aggression and self-aggression in the patients with Schizophrenia, respectively with Bipolar disorder, depressive episode and Major depression disorder were assessed with Buss Perry Aggression Questionnaire and Suicide Intent Scale. Regarding the severity of aggression in the young patients from our study (Buss Perry scale score), male gender is higher than female gender: higher percentages in males (35% and 10%) than in females (16 and 0%). Determining aggression in schizophrenia is possible due to COMT polymorphism that lead to impulsivity or psychotic symptoms. The study show a significant positive correlation between the severity of symptoms of schizophrenia and aggression. From the analysis of the severity of depression in young patients (SIS score) it is noted that its severity is higher in the female gender. Women had higher scores of moderate depression (58%) and severe (26%) than men (37 and 25%, respectively). This relationships could be possible due to the polymorphism of the gene encoding the 5-HTT serotonin transporter related with serotonin deficiency.The study do not show a significant positive correlation between the severity of the depressive symptomatology and the degree of the suicide intent.