PTSD: National Center for PTSD
Co-occurring PTSD and Neurocognitive Disorder (NCD)
Co-occurring PTSD and Neurocognitive Disorder (NCD)
Research findings over the past decade have shown a connection between posttraumatic stress disorder (PTSD) and neurocognitive disorders (NCD) among older adults and those who experienced traumatic brain injuries (TBI). However, we do not have sufficient data to fully understand the complex pathways through which PTSD and NCD alter one another's risk and expression.
In This Article
NCD and Dementia
NCD refers to the group of disorders in which the primary clinical concern is acquired cognitive impairment rather than developmental cognitive impairment. With the release of the 5th edition of the Diagnostic and Statistical Manual (DSM-5), the term "dementia" was subsumed by the classification NCD (1). It is noted in DSM-5 that "dementia" may be retained for use in settings where the term is customary and understood by patients and clinicians. However, NCD is preferable, especially for conditions that affect younger individuals and are not degenerative (e.g., secondary impairment to TBI or HIV). As cognitive deficit can occur in a number of domains (i.e., complex attention, executive function, learning and memory, language, perceptual-motor, and social cognition), the broader definition of NCD is also useful when decline occurs in a single domain, rendering the term "dementia" inaccurate (1).
Mild NCD Versus Major NCD
The diagnoses categorized as NCD exist on a continuum from mild to major cognitive and functional impairment. Decline at any level of the continuum can be acquired from a number of sources including TBI, substance or medication use, HIV infection, Alzheimer's disease, or other brain diseases. Major NCD, regardless of the manner in which it was acquired, is characterized by significant cognitive decline relative to a previous level of functioning as well as high impairment in daily functioning. Mild NCD involves moderate cognitive deficits that do not interfere with basic daily functioning but is associated with greater effort or accommodation to maintain functioning (1).
PTSD and NCD Co-occurrence
Bi-directional relationship between PTSD and NCD
Cross-sectional—and increasingly longitudinal—studies indicate that earlier PTSD is a risk factor for the later development of NCD (2,3). A meta-analysis of 12 longitudinal studies comparing risk for NCD in people with versus without PTSD found that PTSD was associated with 1.6 times greater risk of developing all-cause dementia (3). The risk of developing NCD was actually somewhat higher in general populations versus Veteran populations (3).
Is it possible that the development of NCD can also influence PTSD? A systematic review found much less systematic evidence for this causal direction (versus PTSD leading to NCD), but did find 11 publications including 39 total cases, where the development of NCD appeared to lead to delayed-onset, recurrent, or worsened PTSD (2).
The pathways through which PTSD and NCD affect each other are unclear. There are multiple shared comorbidities (e.g., depression, alcohol use, hypertension, and cardiovascular disease) along with increasing evidence of the association of PTSD with accelerated aging, neurocognitive changes, and several other physical manifestations of chronic stress, all of which would need to be untangled in order to understand the complex relationship between PTSD and NCD.
Possible risk factors for concurrent PTSD and NCD
One common shared risk factor for the development of PTSD and NCD is the presence of a mild traumatic brain injury (mTBI). Most research on TBI and PTSD suggests that experiencing mTBI places one at greater risk for PTSD and NCD (4). For example, among injured patients admitted to a trauma hospital, those who sustained a mild TBI were 1.92 times more likely to have PTSD than those injured without a mild TBI (5). Similarly, in a sample of U.S. soldiers 3 to 4 months after returning from deployment to Iraq, 43.9% who reported loss of consciousness (due to injury) met criteria for PTSD compared with 16.2% who sustained other physical injury and 9.1% who were not injured (6). While it is well established that as TBIs become more severe the risk of cognitive impairment also increases (7), several studies have suggested that PTSD is less likely to occur in the context of moderate and severe, compared to mild, TBI possibly due to the hypothesized protective nature of loss of consciousness during or directly following a traumatic event (8,9).
Substance use also may increase the risk for both NCDs and PTSD. One study found that Veterans with substance use disorder (SUD) who were residents of a VA residential nursing home had higher rates of PTSD, dementia, and physical problems compared to those without SUD (10).
Conclusions
PTSD and NCD often co-occur and having one increases the risk of developing the other. The 2 conditions also share several risk factors including mTBI and SUD. While research has identified a connection between PTSD and NCD, the direction and specific nature of the relationship between them has not been established. For more information about assessment and treatment considerations, see Assessment and Treatment for PTSD with Co-occurring Neurocognitive Disorder (NCD).
References
- American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed). https://doi.org/10.117/appi.books.970890425596
- Desmaris, P., Weidman, D., Wassef, A, Bruneau, M., Friedland, J., Bajsarowicz, P., Thibodeau, M, Herrmann, N., & Nguyen, Q. D. (2019). The interplay between post-traumatic stress disorder and dementia: A systematic review. American Journal of Geriatric Psychiatry, 28(1), 48-60. https://10.1016/j.jagp.2019.08.006
- Günak, M. M.m Billings, J., Carratu, E., Marchant, N. L., Favarato, G., & Orgeta, V. (2020). Post-traumatic stress disorder as a risk factor for dementia: Systematic review and meta-analysis. The British Journal of Psychiatry, 217(5), 600-608. https://10.1192/bjp.2020.150
- Loignon, A., Ouellet, M. C., & Belleville, G. (2020). A systematic review and meta-analysis on PTSD following TBI among military/Veteran and civilian populations. The Journal of Head Trauma Rehabilitation, 35(1), E21-E35. https://doi.org/10.1097/HTR.0000000000000514
- Bryant, R. A., O'Donnell, M. L., Creamer, M., McFarlane, A. C., Clark, C. R., & Silove, D. (2010). The psychiatric sequelae of traumatic injury. American Journal of Psychiatry, 167(3), 312-320. https://doi.org/10.1176/appi.ajp.2009.09050617
- Hoge, C. W., McGurk, D., Thomas, J. L., Cox, A. L., Engel, C. C., & Castro, C. A. (2008). Mild traumatic brain injury in U. S. soldiers returning from Iraq. The New England Journal of Medicine, 358(5), 453-463. https://doi.org/10.1056/NEJMoa072972
- Dikmen, S. S., Corrigan, J. D., Levin, H. S., Machamer, J., Stiers, W., & Weisskopf, M. G. (2009). Cognitive outcome following traumatic brain injury. Journal of Head Trauma Rehabilitation, 24(6), 430-438. https://doi.org/10.1079/HTR.0b013e3181c133e9
- Jamora, C. W., Young, A., & Ruff, R. M. (2012). Comparison of subjective cognitive complaints with neuropsychological tests in individuals with mild vs more severe traumatic brain injuries. Brain Injury, 26(1), 36-47. https://doi.org/10.3109/02699052.2011.635352
- Glaesser, J., Neuner, F., Lutgehetmann, R., Schmidt, R. & Elbert, T. (2004). Posttraumatic stress disorder in patients with traumatic brain injury. BMC Psychiatry, 4, 5. https://doi.org/10.1186/1471-244X-4-5
- Lemke, S., & Schaefer, J. A. (2010). VA nursing home residents with substance use disorders: Mental health comorbidities, functioning, and problem behaviors. Aging & Mental Health, 14(5), 593-602. https://doi.org/10.1080/13607860903586169
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