About this Research Topic
The Guest Editors and Editorial Office are indebted to the critical contribution made by Joyce Harary in coordinating this Research Topic - she has been instrumental to it's success.
Veterans are at an increased risk to develop dementia as well as neuropsychiatric disorders. Neuropsychiatric disorders prevalent in veterans, including depression and post-traumatic stress disorder (PTSD), act as independent risk factors for later development of dementia; and both disorders are also associated with higher rates of suicide, a major health concern within the veteran population. The shared pathogenic phenotypes observed in veterans diagnosed with neuropsychiatric and dementia-related disorders will, therefore, form the subject of this Research Topic. Specific chapters will also discuss the shared cellular and molecular substrates within veterans with neuropsychiatric disorders and/or dementia that future studies may target for the development of clinical biomarkers or potential therapeutic targets.
Epidemiological and clinical studies support an association between psychiatric disorders in veterans and their increased risk for dementia. Veterans with PTSD exhibit nearly a 2-fold higher risk for the development of dementia, while older veterans with depression have a substantial increased risk for development of dementia. Depression shares certain neuropsychiatric deficits with dementia. These include impaired working memory and attention, altered sleep patterns, and reduced psychosocial interactions. The shared neuropsychiatric deficits provide clinical evidence that veterans may share underlying pathophysiological mechanisms that promote their pathologies and cognitive impairments.
Efforts have been put forth to identify pathological biological and cellular mechanisms in veterans with psychiatric and dementia-type disorders. A number of mechanisms have been identified that are associated with their deployment or are consequent to traumatic brain injury (TBI). TBI is a significant post-deployment risk factor that increases susceptibility for both psychiatric disorders and dementia. Dysregulated immune responses have been observed in Veterans with PTSD and depression and have been recapitulated in model systems of stress-induced depression. Persistent immune activity is also observed in Veterans that present with different dementias. Previous studies show how exposures to immunological instigators such as psychological stress or infection increase susceptibility for amplified or persistent immune responses later in life. As veterans were often exposed to immunological stimulators during their deployments, such as certain pathogens and neurotoxins, their noted dysregulated immune activity may be related to exposures to these toxins. Priming of veterans immune system is one pathological mechanism that may therefore increase veterans susceptibility to both neuropsychiatric and neurodegenerative disorders. In addition, veterans diagnosed with both dementia and depression also exhibit metabolic perturbations. Impaired regulation of glucose homeostasis is a pathogenic phenotype in veterans that increases their risk for both the development of dementia and depression. Metabolic and immune impairments are two characterized physiological abnormalities with neuropsychiatric and dementia-related disorders. However, additional studies discussed here in these chapters will review the emerging cellular and molecular substrates that may impair mental health in veterans.
Mental health issues represent a significant economic and personal burden for veterans, and increase veterans’ susceptibility for their later development of dementia. Available resources should therefore be devoted to understand and characterize pathological mechanisms that may contribute to both disorders. Results from these studies may then be translated into specific guidelines and approaches policymakers can provide that are specific to veterans. In doing so, we can promote health in veterans, and reduce their risk for suicide and other neurological conditions.
Keywords: PTSD (post-traumatic stress disorder), depression, dementia, cognitive impairment, neuropsychiatry
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