, new research suggests.
In an analysis of more than 12,000 middle-aged women who had experienced at least one trauma in their lives, those with PTSD symptoms showed an approximately twofold faster decline in cognition during follow-up compared with those who did not have PTSD symptoms.
These associations were not fully explained by other known cognition-related factors such as depression, the researchers noted.
“PTSD may increase the risk of dementia by accelerating cognitive decline at midlife,” coinvestigator Jiaxuan Liu, a doctoral candidate at Harvard TH Chan School of Public Health, Boston, said in an interview.
“Our findings may suggest the value of earlier cognitive screening among individuals with PTSD and the importance of PTSD prevention and treatment across the lifespan,” she added.
The results were published online in JAMA Network Open.
Vital public health issue
“Cognitive decline at midlife and older is of vital public health interest,” Ms. Liu said. “It is a risk factor for a variety of poor health outcomes and strongly predicts Alzheimer’s disease and other dementias.
Although PTSD has been linked to lower cognitive function and dementia incidence, it has not been known whether it is associated with decline in cognitive function, she added.
“In addition, both PTSD and dementia are more common in women than men, so it’s important to understand a possible link,” Ms. Liu said.
Because no large-scale study had examined whether PTSD is associated with cognitive decline in women, the current researchers examined PTSD symptoms and their association with repeated measures of cognitive function among a large civilian trauma-exposed cohort of women aged 50-70 years at study baseline.
Participants were drawn from the Nurses’ Health Study II, a longitudinal study of a cohort of 116,429 U.S. female nurses who were between 25 and 42 years old at enrollment in 1989. Participants completed biennial questionnaires, with follow-up on an ongoing basis.
The current analysis included 12,270 trauma-exposed women (mean age at baseline, 61.1 years) who completed assessments every 1 or 12 months for up to 24 months after baseline. The mean follow-up time was 0.9 years.
In the study population, 95.9% were non-Hispanic White, 1.3% were Hispanic, 1% were Asian, 0.6% were Black, and 1.2% were classified as “other.”
Higher depression scores
Lifetime trauma exposure and PTSD symptoms were assessed from March 1, 2008, to Feb. 28, 2010, using the Short Screening Scale for DSM-IV PTSD.
In total, 67% of the participants reported experiencing PTSD symptoms. The women were divided into four groups, on the basis of symptom number: no PTSD symptoms (n = 4,052), one to three PTSD symptoms (n = 5,058), four to five PTSD symptoms (n = 2,018), and six to seven PTSD symptoms (n = 1,052).
The Cogstate Brief Battery, a validated and self-administered online cognitive assessment, was completed by participants between Oct. 3, 2014, and July 30, 2019. The researchers measured cognitive function with two composite scores: psychomotor speed and attention, and learning and working memory.
Covariates potentially associated with cognitive decline included demographic, educational, and behavior-related health factors such as body mass index, physical activity, cigarette smoking, diet quality, and alcohol consumption.
The researchers conducted secondary analyses that adjusted for symptoms and history of depression as well as the consequences of potential practice effects of taking the test multiple times.
Behavior-related health factors “did not substantially differ by PTSD symptom level,” the investigators noted. However, compared with women who did not have PTSD symptoms, those who had such symptoms had higher depressive symptom scores and higher rates of clinician-diagnosed depression.
Both cognitive composite scores improved through the follow-up period, “likely because of practice effects,” the researchers wrote. But after adjusting for practice effects, they found a decline over time in both composite scores.