In the article, in light of the hypothesis about the pathogenesis of epilepsy the author considers certain clinical manifestations of epilepsy, touches upon the neurochemistry of behavior, as well as neurotransmitter hypothesis of schizophrenia. According to the hypothesis, in epileptic patients, epileptogenic substances are permanently accumulating in the brain, which in the course of epileptic activity in the brain undergo metabolic changes requiring their removal from the organism. When the concentration of epileptogenic substances in the brain reaches a threshold value, they cause a seizure, and in lower concentrations, they cause epileptic activity typical for the interictal period. In the context of this hypothesis, there are discussed the clinical signs of epilepsy such as forced normalization, reinforcement epilepsy activity during the sleep deprivation and one of the paradoxical effect of antiepileptic drugs such as phenomenon when antiepileptic drugs prescribed cause an improvement of the electroencephalographic image but the clinical deterioration and increasing frequency of seizures, and the change of antiepileptic drugs give us the opposite results: improvement of the clinical picture and the deterioration of the electroencephalographic image. The author suggests names for this type of dissociation (discrepancy) between the clinical and electroencephalographic picture and for the electroclinical dissociation discovered earlier by Weiner, and also for clinical-electroencephalographic dissociation of forced normalization with the ability to easily give names to other types of clinical and electroencephalographic dissociation discovered in the future in patients with epilepsy. According to the supplemented hypothesis, epileptogenic substances, except that, during epileptic activity in the brain undergo metabolic transformations necessary for their removal from the body; there are alsoalternative transformation neurochemical pathways necessary for their further removal (elimination) from the organism. The hypothesis discusses the modern principles of epilepsy and mental diseases treatment. Forced normalization is considered as one of the manifestations of epilepsy aggravation and “clinical-electroencephalographic dissociation”. When reviewing biological antagonism of schizophrenia and epilepsy the author suggests a hypothesis that if an area of the brain producing epileptogenic substances and an area of the brain producing endogenic psychogenic substances causing psychopathology coexist simultaneously, then, in the event of a generalized convulsive seizure involving the brain in full, epileptogenic as well as psychogenic substances are released. At the same time epilepsy is demonstrated, while schizophrenia is not. The same could be the mechanism of therapeutic activity (effect) of electroconvulsive therapy. Psychogenic substances can also be released through interictal epileptic activity. The significance of the blood-brain barrier is considered. In addition to the antiepileptic and antipsychotic system of the brain, the concepts of the borderline and extracerebral antiepileptic and antipsychotic systems are proposed, where the blood-brain barrier is presented as the borderline antiepileptic and antipsychotic system.