The Department of Veterans Affairs has published a proposed regulation in the Federal Register that would change its rules to add five diagnosable illnesses which are secondary to service-connected traumatic brain injury. The proposed regulation is available online here. 
VA proposes to add a new subsection to its adjudication regulation by revising 38 CFR 3.310 to state that if a veteran who has a service-connected TBI also has one of the five illnesses, then the illness will be considered service connected as secondary to the TBI.
Service connection under the proposed rule depends in part upon the severity of the TBI – mild, moderate or severe – and the period of time between the injury and onset of the secondary illness. However, the proposed rule also clarifies that it does not preclude a veteran from establishing direct service connection even if those time and severity standards are not met. It also defines the terms mild, moderate and severe, consistent with Department of Defense guidelines.
Comments on the proposed rule will be accepted over the next 60 days. A final regulation will be published after consideration of all comments is received.
VA's decision is based on a report by the National Academy of Sciences, Institute of Medicine (IOM), "Gulf War and Health, Volume 7: Long-Term Consequences of TBI." In its report, the IOM's Committee on Gulf War and Health concluded that "sufficient evidence of a causal relationship" - IOM's highest evidentiary standard - existed between moderate or severe levels of TBI and diagnosed unprovoked seizures. The IOM found "sufficient evidence of an association" between moderate or severe levels of TBI and Parkinsonism; dementias, which VA understands to include presenile dementia of the Alzheimer type and post-traumatic dementia; depression (which also was associated with mild TBI); and diseases of hormone deficiency that may result from hypothalamo-pituitary changes.