NEGATIVE SYMPTOMS IN SCHIZOPHRENIA - CONSIDERATIONS FOR CLINICAL-TRIALS

There is little agreement about the methodology of clinical trials of antipsychotic drugs in patients with negative symptoms. A literature r eview revealed wide variation in experimental design, rating scales an d study duration. This reflects differing views as to the definition a nd response to treatment of negative symptoms. Some degree of standard ization would improve comparability of studies and aid the development of new compounds. Patients included in such studies should have displ ayed negative symptoms for at least 6 months. Depressive symptoms, pos itive schizophrenic symptoms and extrapyramidal signs may all in fluen ce or be confused with negative symptoms and may respond to treatment; they should be at a low level at baseline and should be measured duri ng the study period. Studies should last at least 8 weeks. Several sca les are available for measuring negative symptoms and are reviewed; a global impression score should be used additionally.