This disclosure is directed to pyrido[4,3-b]indoles having rigid moieties. The compounds in one embodiment are pyrido[4,3-b]indoles having an unsaturated hydrocarbon moiety. The compounds in another embodiment are pyrido[4,3-b]indoles having a cycloalkyl, cycloalkenyl or heterocyclyl moiety. Pharmaceutical compositions comprising the compounds are also provided, as are methods of using the compounds in a variety of therapeutic applications, including the treatment of a cognitive disorder, psychotic disorder, neurotransmitter-mediated disorder and/or a neuronal disorder.