Although a wide variety of methods are available for the de novo design of drugs to inhibit a target deemed to be useful for chemotherapy (de Souza Neto et al., 2020) , only a few of these can be easily adapted for the design of CNS drugs, because most molecules are unable to cross the BBB. Generative AI models that can produce molecules with a specified distribution of properties are particularly promising . However, for some applications, evolutionary algorithms have the advantage that models need not be retrained for selection of fragment libraries, selection of libraries of chemical reactions for generating mutations, or for modification of fitness function .