The present invention is concerned with a method of treating a disease selected from the group consisting of cognitive disorders, anxiety, Alzheimer's disease, and schizophrenia comprising administering a therapeutically effective amount of a substituted imidazo[1,5-a][1,2,4]triazolo[1,5-d][1,4]benzodiazepine derivatives of the following formula wherein R1 is halogen, lower alkyl, lower alkynyl, cycloalkyl, lower alkoxy, OCF3, —NHR, —NHC(O)R or —NHSO2R; R2 is hydrogen, methyl or aryl which is unsubstituted or substituted by one or two substituents selected from the group consisting of halogen and lower alkoxy; R3 is hydrogen, lower alkyl, lower alkenyl, cycloalkyl, lower alkoxy, —O(CH2)n+1—O-lower alkyl, —(CH2)n-aryl which is optionally substituted by lower alkyl or halogen, heteroaryl, —NHR, —N(R)2, wherein each R can be the same or different, —NHCH2C≡CH, or pyrrolidin-1-one; R is hydrogen, lower alkyl, lower alkyl substituted by halogen, heteroaryl, —(CH2)nO-lower alkyl, —NH-lower alkyl, cycloalkyl or aryl, and n is 0, 1, 2 or 3; and with their pharmaceutically acceptable acid addition salts. The invention also provides novel compounds of formula I-A and pharmaceutical compositions containing them. The most preferred indication is Alzheimer's disease.