Veterans of the first Gulf War (1990–1991) are reaching middle and older adulthood in differing degrees of health and biological age. Many Gulf War veterans report myriad negative symptoms classified as Gulf War illness (GWI), a chronic multi-symptom illness.

To describe and analyze deficit accumulation, among veterans with Severe GWI (SGWI+) and those without Severe GWI (SGWI−), to assess the association between a medically unexplained illness and aging.

This study uses a retrospective cohort design with quasi-longitudinal data.

The recruitment sample included 10,042 Gulf War era veterans across all four US Census regions.

The analytic sample included 1,054 participants of the GWECB for whom SGWI case status could be determined and who had valid responses for at least 90% of the deficits included in the deficit accumulation index.

Chronic health conditions were retroactively reported, including year of diagnosis, enabling us to create a longitudinal measure of deficit accumulation. This deficit accumulation index (DAI) ranged from 0–1 for each respondent in each year between 1991–2013. We compare veterans with SGWI+ to those with SGWI− using the CDC case definition.

Most veterans in our sample could expect to spend more years with moderate or substantial deficits than without deficits. SGWI+ was associated with spending more years with substantial deficits than those with SGWI−. Veterans in middle age (age 35–65) experienced more years with substantial deficits than younger veterans. Individuals with SGWI+ had 13 times the hazard of accumulating substantial deficits than those without.

This study demonstrated that veterans with SGWI+, even those in midlife, experienced aging as measured by accumulating deficits. Practitioners should consider patients with multi-symptom illnesses as at risk of accelerated aging, tailoring treatments to address patients’ holistic needs.