Is PTSD tied to cognitive decline in middle-aged women?

A large prospective study has shown an association between post-traumatic stress disorder (PTSD) and accelerated decline in cognitive function over time in middle-aged women, underpinning the importance of earlier cognitive screening in women with PTSD.

“Cognitive decline at midlife and older is of substantial public health interest because it is a risk factor for worse health in a wide variety of domains,” said the researchers. Given evidence reflecting strong associations between cognitive decline and Alzheimer’s disease and related dementias, it is imperative to identify novel risk and protective factors associated with cognitive decline. [Psychol Aging 2018;33:195-218; J Am Geriatr Soc 2017;65:2627-2633]

The study included 12,270 trauma-exposed women enrolled in the PTSD substudy of the Nurses’ Health Study II. About 70 percent of participants reported experiencing PTSD symptoms. Mean age was 61.1 years at baseline cognitive assessment and 29.7 years at worst trauma. Participants were asked about their exposure to traumatic events (eg, physical assault, natural disasters) and were classified according to PTSD symptom level (ie, no, 1–3, 4–5, and 6–7 symptoms). [JAMA Netw Open 2022;5:e2217698]

After adjusting for demographic factors, women with 6–7 PTSD symptoms had a significantly worse rate of change in learning and working memory (β=−0.08 SD/year; p<0.001), as well as psychomotor speed and attention (β=−0.05 SD/year; p=0.02), than those without symptoms.

A similar association was seen in the comparison between women with 4–5 PTSD symptoms vs those without symptoms in terms of rate of change in learning and working memory (β=−0.03 SD/year; p=0.03) but not in psychomotor speed and attention (β=0.01 SD/year; p=0.41).

Further adjustment for practice effects revealed that women with 6–7 PTSD symptoms experienced cognitive decline in learning and working memory about two times faster than those without symptoms (β=−0.14 vs −0.07 SD/year; p<0.001), at a pace equivalent to 0.69 vs 0.36 SD/5 years. Albeit nonsignificant, greater cognitive decline in psychomotor speed and attention was also seen among women with 6–7 PTSD symptoms vs those without symptoms (β=−0.10 vs −0.07 SD/year; p=0.07; equivalent to 0.51 vs 0.33 SD/5 years).

The findings align with evidence showing similar associations in individuals with exposure to extreme traumas (eg, childhood abuse, sexual abuse, military combat, the Holocaust). [Psychiatry Res 1995;59:97-107; J Nerv Ment Dis 2004;192:643-649; Psychol Bull 2015;141:105-140; J Anxiety Disord 2013;27:550-558] “These studies have generally found that persons with PTSD have lower cognitive function than those without PTSD,” the researchers noted, underlining that the largest cognitive differences in these studies were also in learning and memory.

The results also add to evidence showing that those with PTSD had a higher risk of developing dementia than those without PTSD. [J Am Geriatr Soc 2017;65:1043-1050; Alzheimers Dement 2018;14:28-34] “Our [findings imply] that PTSD may accelerate cognitive decline at midlife and older, thereby increasing the risk of dementia based on the assumption that acceleration in cognitive decline is associated with increased risk of dementia,” they said.

However, there are certain limitations that must be taken into context. The predominance of non-Hispanic white female nurses as participants may have limited generalizability of the findings, while the self-administered screening instrument (Cogstate Brief Battery) – though validated – may have led to misclassification.

“[Nonetheless, our] findings highlight the importance of PTSD prevention and treatment to promote healthy cognitive ageing and suggest that earlier cognitive screening among women with PTSD should be considered,” the researchers concluded.

They called for future studies that could shed light on the mechanisms underlying these associations and to ascertain whether PTSD remission correlates with reduction in cognitive decline. They also suggested evaluating the association between PTSD and cognitive decline beyond 24 months (the study’s maximum follow-up time).