To the Editor: Two recent studies,1,2 including one reported in the Journal of the American Geriatrics Society,1 used Veterans Affairs (VA) patient databases to establish posttraumatic stress disorder (PTSD) as a risk factor for dementia. PTSD and dementia are common and place considerable burden on patients, caretakers, and society.3,4 The co-occurrence of conditions involving memory loss (dementia) and intrusive expression of trauma memories (PTSD) underscores the need to better understand their interactions. Reports of cases in which PTSD worsened with cognitive decline5 and mild cognitive impairment as a precipitant for "delayed-onset PTSD"6 suggest that pathways between dementia and PTSD are bidirectional and that neurodegeneration can disinhibit trauma memories. Current models of PTSD refer to amygdala activation that is inadequately inhibited by higher cortical structures.7 Specific dementia subtypes affect cortical and subcortical structures differently.8 The objectives of the current study were to characterize activation of war trauma memories in veterans with dementia and evaluate relationships with dementia subtypes. Dramatic presentations evaluated by the principal investigator (PI) (DLD) inspired this study, which was conducted by reviewing patient records and was approved by the Washington, DC, VA Medical Center institutional review board. Cases were identified from the complete roster of psychiatric evaluations for a geriatric medicine clinic over a 2-year period based on a diagnosis of dementia and a caregiver's report of new-onset disruptive behavior related to patients' traumatic military experiences. Controls were selected in a 2:1 ratio by identifying patients with dementia who had also served in a war zone but did not have reports of reenactments of traumatic military experiences. After the PI identified cases and controls from the clinic roster, postgraduate trainees reviewed chart files guided by a chart review instrument. Data included demographics; war theater of service; the presence of PTSD, hypertension, diabetes mellitus, stroke, Parkinson's disease (PD), and symptoms associated with Lewy body dementia (LBD) (severe sensitivity to antipsychotic medications, visual hallucinations, and severe sleep wake disturbance); and dementia subtypes that the PI had previously diagnosed using available clinical and laboratory data. Sixteen cases of 197 (8%) patients that the PI saw during the study period met the case criteria. All had episodes with vocalizations of war-related references (e.g., asking for help from soldiers, "secure the perimeter"). For all cases, most episodes occurred at night and appeared to arise from sleep. Seven had episodes in which they were physically combative, including by shielding a spouse from perceived danger. All of the cases and two of the 32 controls had prior diagnoses of PTSD (P<.001). There were no differences in the frequency of other diagnoses except a trend for higher rates of strokes (P<.09), and LBD features were more frequent in the cases (all P<.001). As indicated in Figure 1, the distribution of dementia subtypes was significantly different in the two groups, with all but one case having been diagnosed with a subcortical type of dementia. Percentage of cases and controls with specific dementia subtypes, chi-square=11.3, P<.02. Although preliminary because of the limitations of retrospective chart review and the experience of one clinic, these observations suggest that trauma-related reenactments are not uncommon in older war veterans with dementia and occur in those previously diagnosed with PTSD. Episodes that appear to be dissociative flashbacks can be dramatic and disruptive. A predominance of sleep-related episodes and a preliminary association with subcortical dementias was also found. These associations suggest a relationship with rapid eye movement (REM) behavior disorder (RBD), which features behavioral enactments during sleep due to failure of the normal inhibition of motor activity of REM sleep. RBD has been found to be a prodrome of LBD and PD9 and has been linked to PTSD.10 Thus RBD might provide a relevant model for understanding relationships between trauma memory reactivation of PTSD and dementia. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Dr. Mellman has recently been engaged as a consultant to Eisai pharmaceuticals. The activity has no relationship to the study report. Dr. Mellman's activity as a mentor to novice investigators was supported in part by National Institutes of Health Frant K24 MH001917, a midcareer award in patient-oriented research. Author Contributions: Everyone who contributed significantly to the work has been included in the authorship, and all authors contributed to the conception and design, acquisition of data, analysis and interpretation of data; drafting the article or revising it critically for important intellectual content; and final approval of the submitted manuscript. Sponsor's Role: There was no external sponsorship of the study.
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