While researching material for a book on Abraham Lincoln, Dr. John G. Sotos came across a letter written in 1852 in which Mary Todd Lincoln (1812-1882) is described as having a 'sore mouth'. Knowing this to be a common symptom of vitamin B12 deficiency (glossitis), the Johns Hopkins trained cardiologist, former chief scientist to WebMD and medical science advisor to multiple medical television series, began to collate medical accounts of the former First Lady's checkered life.

In a scholarly article published in 2016 and his book "The Mary Lincoln Mind-Body Sourcebook" (Mt. Vernon Book Systems, 2017), Dr. Sotos makes the case that no single diagnosis can explain the 30 year history of multiple, poorly defined symptoms and psychiatric illness as well as Pernicious Anemia does. He points out that her parents were both from a part of Scotland in which Pernicious Anemia was found to be more prevalent than expected and with her pallor, paresthesias, ataxia, episodic weakness, depression, frequent delusions, hallucinations and psychotic behavior, provide strong support for a diagnosis that had not been described yet - severe vitamin B12 deficiency.

Historical diagnoses are intriguing and whether or not they can be proven, should not diminish the value they provide. Whether Mrs Lincoln had Pernicious Anemia is not as important as that her many ailments are quite compatible with untreated severe vitamin B12 deficiency, many of which are often forgotten about today. This is the value of Dr. Sotos' medical sleuthing.