Abstract: The presently disclosed invention relates to a method of diagnosing Multiple Sclerosis (MS) in a patient comprising obtaining a sample from the patient, determining a level of one or more H2S generating enzymes in the sample from the patient, and diagnosing the patient with MS when the level of the one or more H2S generating enzymes is one of at least 15% higher or lower than a control level for the one or more H2S generating enzymes, and at least 10% higher or lower than a control level for the one or more H2S generating enzymes.

Abstract: A method of diagnosing Alzheimer's disease and related dementias (ADRD) in a patient comprising obtaining a plasma sample from the patient; determining a level of a biochemical sulfide in the plasma sample from the subject by trapping volatilized H2S in the plasma sample using alkaline buffer with monobromobiamine, and detecting the level of biochemical sulfide in the plasma sample, the biochemical sulfide being one of acid-labile sulfide, bound sulfide, and total sulfide; and diagnosing the patient with ADRD when the level of the biochemical sulfide is at least an elevated threshold level for the biochemical sulfide.