The present invention generally relates to the use of drugs for the treatment of neurobehavioral disorders or symptoms of a neurobehavioral disorder associated with dysfunction of the trimonoamine modulating system (TMMS). More specifically, the invention describes methods for the treatment of a neurobehavioral disorder and/or treatment or prevention of symptoms of a neurobehavioral disorder by administering suitable Isoindole derivatives alone or in combination with other agents so as to provide relatively equal inhibitory effect on serotonin, dopamine and norepinephrine transporters.