Dr. Johnston's research has focused on treatment and outcomes in acute ischemic stroke and she is the principle investigator on numerous NIH funded grants. She participates in numerous NIH-NINDS study sections and data safety monitoring committees and is chair of the NIH-NINDS clinical research collaboration (CRC) advisory team. She was an associate editor of the journal Neurology and the founding editor of the neurology resident and fellow section. She maintains a strong commitment to education and mentoring.