COMMENTARY

Dementia Risk May Be Increased in Female Veterans

Laurie Barclay, MD

Disclosures

January 24, 2019

Military-Related Risk Factors in Female Veterans and Risk of Dementia

Yaffe K, Lwi SJ, Hoang TD, et al
Neurology. 2018 Dec 12. [Epub ahead of print]

Study Summary

Previous research suggests that male veterans with military-related traumatic brain injury (TBI), posttraumatic stress disorder (PTSD), or depression may be at increased risk for dementia in later life. This cohort study sought to assess whether the same conditions increased the risk for dementia in older female veterans also, something that is presently undetermined.

Investigators analyzed data from 109,140 female veterans aged 55 years or older (mean age, 69 years) who were free of dementia at baseline and had at least one follow-up visit at US Veterans Health Administration medical centers between October 2004 and September 2015. Diagnoses of baseline TBI, PTSD, depression, and medical conditions and incident dementia were based on ICD-9-CM codes obtained from medical record review. The association between military-related risk factors and dementia diagnosis was analyzed using Fine-Gray proportional hazards models that considered the competing risk for death.

Of the 109,140 female veterans in the study cohort, 20,410 had depression only, 1363 had PTSD only, and 488 had TBI only, whereas 5044 had more than one of these conditions and 81,135 had none. Dementia developed during follow-up (mean 4.0 years, standard deviation 2.3 years) in 4125 female veterans (4%) overall, including 5.7% of women with TBI, 5.2% of those with depression, 3.9% of those with PTSD, 3.9% of those with more than one condition, and 3.4% of those with none of the conditions.

Compared with participants without TBI, PTSD, or depression, those with any of these diagnoses had a significant increase in risk of developing dementia, after adjustment for demographics and medical conditions that could affect dementia risk, such as hypertension, diabetes, and alcohol abuse. Subdistribution hazard ratio (sHR) was 1.49 (95% confidence interval [CI], 1.01-2.20) adjusted for TBI, 1.78 (95% CI, 1.34-2.36) adjusted for PTSD, and 1.67 (95% CI, 1.55-1.80) adjusted for depression. Dementia risk was more than doubled in female veterans with more than one of these diagnoses (adjusted sHR, 2.15; 95% CI, 1.84-2.51).

Viewpoint

This study is limited by its reliance on medical diagnosis codes to ascertain TBI, PTSD, and depression, which might fail to capture women with less severe symptoms of these disorders. In addition, the observational design precludes causal inferences regarding the association of these disorders with dementia risk.

Despite these limitations, the findings suggest that female veterans with military-related risk factors had an approximately 50%-80% increased risk of developing dementia compared with those without these diagnoses, and that risk was more than doubled in those with multiple risk factors. The findings are similar to those documented previously among male veterans.

As more women enter military service and assume combat roles, greater understanding is needed regarding the association between development of dementia and exposure to TBI, PTSD, and/or depression, especially because women may be at increased risk for some of these military-related diagnoses. Nearly one third of veterans deployed for Operations Enduring Freedom and Iraqi Freedom are estimated to have one or more of these conditions.

The findings support the need for clinicians to increase screening for TBI, PTSD, and depression in older women, especially female veterans. Women with any of these risk factors should undergo closer monitoring for development of dementia. Future studies should evaluate whether treatment of these military-related conditions is associated with mitigation of increased dementia risk.

 

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