The author of the term "borderline personality disorders" is considered to be the psychoanalyst Stern, who distinguished the following features of this disorder: mental pain, narcissism, hypersensitivity, inflexibility of the body and mind, lack of a sense of security, masochism, projection mechanisms and disorders of perception of reality. Biological factors include: dysfunction of the limbic system, damage to the central nervous system, including organic damage to the brain (perinatal trauma, encephalitis, trauma to the head), and epileptic episodes (1, 2).

We present the case of a 20-year-old patient treated at the Department of Psychiatry of Collegium Medicum in Bydgoszcz. The patient had a borderline personality, characterized by instability of relationships, the image of herself and emotions, and a lack of control over impulses. She lived with a sense of abandonment by others, and had a tendency to start intense, unstable relationships with men, often leading to emotional crises. Frequently, without understandable reasons, she formulated suicidal threats or made self-inflicted injuries on her body, and experienced uncontrolled bursts of anger. She also had a tendency to impulsive behaviour, regardless of its consequences, and was characterized by emotional instability. Her ability to plan the future was almost non-existent, and bursts of anger often led to sudden behaviours or "behavioural explosions". Anger was often triggered by criticism or by her impulsive actions being counteracted by other people. She complained about a constant feeling of internal emptiness. The patient underwent year-long cognitive-behavioural psychotherapy, with a good therapeutic effect. In order to reduce the disorders in the control of impulsive-behavioural behaviours, the patient was treated to good therapeutic effect with a selective serotonin reuptake inhibitor (SSRI), sertraline, in a dose of 100 mg/day for 12 months.

Contemporary literature concerning borderline personality assigns a significant role to mental experiences related to traumas from childhood, such as molestation and sexual harassment, as well as negligence of the child's emotional and developmental needs. About 40-71% of patients with borderline personality report that they have experienced sexual molestation (3, 4). It has been observed that there is a connection between the extent to which a given person was sexually molested in childhood and the intensity of disorders typical of the borderline personality. Other significant factors for development of the disease are a family medical history associated with alcoholism or drug addiction, and affective disorders among close relatives (5, 6). Impulsive behaviours observed in patients with borderline personality disorders may be associated with changes in the areas of the frontal-limbic system of the brain related to suppressing aggression. This applies particularly to such areas of the brain as: the frontal-orbital cortex, the prefrontal dorsolateral cortex, the anterior cingulate cortex (ACC), and the amygdala-hippocampal region. Biological predisposi-tions, apart from affective instability and excessive aggressiveness, as well as impulsiveness, include: hypersensitivity to rejection leading to dysphoria, chronically lowered mood, frequent depressive reactions, frequent bursts of anger, and chronically elevated level of aggression (7, 8). It is believed that severe psychosocial traumas, which include loss of one or both parents, and sexual or physical abuse (beating), predispose to affective disorders and impulsive-aggressive behaviours through likely changes in neurotransmitters of the brain. The described circumstances seem to point to an important role played by physical or emotional trauma, which is destructive to the emotional, social and cognitive functioning of an individual, leading, in the first place, to disintegration of "the ego" then loss of the sense of identity, and resulting in specific defence mechanisms, such as split personality or denial and creation of a false "ego", which often manifests itself as a lack of awareness of one's own needs, feelings and wishes. The false "ego" reflects external requirements. Self-inflicted injuries may be a reaction to trauma. An ill person harms and rejects him- or herself by performing the role of "an injuring carer". Strong fear of closeness, as well as disorders with regard to the sense of identity in adult life, derive from negative experiences in childhood. Disorders with regard to the sense of identity manifest themselves in a lack of awareness of one's own needs, lack of sense of security, lack of trust towards oneself and other people, as well as self-assessment instability, to an extreme sense of worthlessness. The sense of rejection by close friends and relatives is the cause of uncomfortable and very strong feelings of anger and irritation, leading to a specific condition of mental chaos, causing confusion (9, 10).

1. The purpose of therapy in the patient with borderline personality was to alleviate the symptoms and improve the functioning, in particular, eliminate the acts of auto-aggression. In reaching the intended therapeutic effect, the selection of suitable therapeutic methods - psychotherapy and sertraline pharmacotherapy - was of major importance.

2. In the relationship with a patient with borderline disorders one has to ensure a working alliance, monitor the patient's security, and respond to changes in symptoms or observed crises. Sometimes it is more important to provide security to the patient, and sometimes to pay attention to improving relations with the therapist or functioning during treatment.