ME/CFS Brain Fog: Cognitive Rehabilitation Trial

Inclusion Criteria: * diagnosis of ME/CFS that preceded cognitive complaints * mild or greater cognitive impairment * moderate or greater brain fog * some impairment in the performance of daily activities * ≥ 18 years, no upper limit if medically stable * reside in the community (as opposed to a hospital or skilled nursing facility) * able to travel to the laboratory on multiple occasions * has Internet service * has a personal computer, laptop, or tablet that can access the Internet * sufficiently fit, from both a physical and mental health perspective, to take part in the study * adequate sight and hearing to complete the UFOV test * adequate thinking skills, e.g., ability to follow directions and retain information to complete UFOV and CTAL, as marked by the judgement of the screener that the candidate is able to adequately complete the UFOV and CTAL * sufficient English proficiency (i.e., ability to speak, understand, read, and write to take part in study activities) Exclusion Criteria: * cognitive impairment due to a developmental disability, psychiatric disorder, or substance abuse, or due to another type of brain injury, such as traumatic brain injury, stroke, or a progressive brain disease, such as Alzheimer's Dementia * current substance abuse disorder * diagnosis of postural orthostatic tachycardia syndrome (POTS) by a healthcare provider * prior cognitive processing speed training on DoubleDecision or a similar program * cannot tolerate taVNS * prior history of heart attack or other serious cardiac events * implanted medical device of any type * vasovagal syncope or history of fainting * history of seizures or epilepsy * temporomandibular Joint (TMJ) syndrome or other conditions that cause substantial jaw pain * history of peripheral nerve injury to the head, neck, or face * pregnant or breastfeeding * not able or willing to get an MRI scan * not able or willing to get a blood draw