In studies made in the last decade, patients consulting doctors because of depression and anxiety have very often turned out to suffer from bipolar type II and similar conditions with alternating depression and hypomania/mania (the bipolar spectrum disorders - BP). Specifically, about every second patient seeking consultation because of depression has been shown to suffer from BP, mainly bipolar type II. BP is often concealed by other psychiatric conditions, e.g. recurrent depression, psychosis, anxiety, addiction, personality disorder, attention-deficit hyperactivity disorder and eating disorder. BP shows strong heredity. Relatives of patients with BP also have a high frequency of the psychiatric conditions just mentioned. Conversion ("switching") from recurrent unipolar depressions (recurrent UP) to BP is common in very long longitudinal studies (over decades). Mood-stabilizing medicines are recommended to a great extent in the treatment of BP, since anti-depressive medicines are often not effective and involve a substantial risk of inducing mood swings. Particularly in the long-term pharmacological treatment of depression in BP anti-depressive medicines may worsen the condition, e.g. inducing a symptom triad of dysphoria, irritability and insomnia: ACID (antidepressant-associated chronic irritable dysphoria).