This application provides for a method of increasing brain-derived neurotrophic factor (BDNF) serum level in a human subject comprising periodically administering to the subject an amount of laquinimod or pharmaceutically acceptable salt thereof effective to increase BDNF serum level in the human subject. The method can further comprise periodically administering to the subject an amount of a second BDNF-increasing agent. This application also provides for a method for treating a human subject suffering from a BDNF-related disease comprising periodically administering laquinimod or a pharmaceutically acceptable salt thereof in an amount effective to treat the human subject. This application additionally provides for use of laquinimod in the manufacture of a medicament for increasing BDNF serum level in a human subject. This application further provides for a pharmaceutical composition comprising an amount of laquinimod effective for use in increasing BDNF serum level in a human subject. This application also provides for a pharmaceutical preparation comprising an amount of laquinimod and an amount of a second BDNF-increasing agent effective for use in increasing BDNF serum level in a human subject.