The present application provides an inhibitory compound, such as a peptide, and methods for using the inhibitory compound in the treatment, diagnosis or monitoring of cognitive and mood disorders that are typically associated with memory loss and/or loss of executive function. In one example, the inhibitory compound is a peptide that mimics the N-terminal sequence of the intracellular loop of α5 subunit of α5GABAA receptors. Also provided are compositions and methods for treating a disorder associated with memory loss or loss of executive function. The therapeutic method comprises the step of inhibiting binding of radixin to α5GABAA receptors, for example, by administration of the presently described inhibitory compound or peptide.