Longitudinal assessment of sleep disordered breathing in Vietnam veterans with post-traumatic stress disorder

Purpose: Previous work has demonstrated the relatively high prevalence of risk factors for cognitive impairment, such as sleep disordered breathing (SDB) and obesity, in Vietnam War era veterans with post-traumatic stress disorder (PTSD). No data are currently available on the longitudinal stability of SDB as a risk factor for cognitive decline in that population, which this study now reports. Methods: Sample consisted of 48 veterans of the Vietnam War with PTSD who completed longitudinal sleep assessments over a 3-year period. The primary outcome measure, the Apnea-Hypopnea Index (AHI) indicator, was determined during standard overnight polysomnography. Body mass index (BMI) was calculated using standard measurements. - Measures of cognitive function tapped auditory verbal memory as measured by the Rey Auditory Verbal Learning Test and executive functioning as measured by the Color-Word Interference Test of the Delis-Kaplan Executive Function System battery. Statistical analyses included mixed effects modeling. Results: In this sample, AHI increased significantly by 2.19 points per year (beta=2.19; P<0.005). AHI worsened over the 3-year period, increasing from a mean of 18.7 +/- 15.7 to 24.7 +/- 17.4 points. Neither BMI nor cognition showed significant change over the 3-year period. Conclusion: SDB worsened in a group of veterans of the Vietnam War with PTSD over a 3-year period. The worsening of SDB over time suggests the need for appropriate countermeasures in populations at risk for progression of the condition.