Abstract
Negative (deficit) symptoms of schizophrenia are a significant cause of poor social functioning and a low quality of life, and their treatment is difficult. The aim of this paper is to review the literature of the last two decades as well as current recommendations regarding their treatment. The introduction of the second-generation antipsychotic drugs (SGA) in mid-1990s brought hope for higher efficacy in the treatment of negative symptoms and improvement of cognitive dysfunctions when compared with the typical neuroleptics. Two decades of treatment experience have proven that all the SGAs are more efficacious than typical neuroleptics, although this difference is moderate. Amisulpride and ziprasidone show a significant efficiency in this respect. Combining other drugs with antipsychotics (add-on strategy) is the most common approach in the treatment of negative symptoms. Antidepressant drugs are the most widely used. Reduction in negative symptoms has been observed after their administration, particularly following mianserin and mitrazapine. Some efficacy has been found for drugs acting as agonists of the glycine site of the NMDA receptor (glycine, D-serine, D-cycloserine) and as glycine transporter's inhibitors (sarcosine), according to a postulate of NMDA glutamate receptor dysfunction in schizophrenia. Good results were observed after the application of drugs affecting the cholinergic system, immunological system, inflammatory processes and hormonal substances – when combined with antipsychotic drugs. Among the non-pharmacological methods, physical activity and brain stimulating methods have shown promising results. Unfortunately, currently available therapeutic methods do not provide a satisfying outcome in the treatment of negative symptoms. Further research in this field is one of the most important challenges of modern psychiatry.