Biomarkers associated with cognitive impairment in post-traumatic stress disorder : A systematic review of current evidence.

Objective
This systematic review aimed at synthesizing current evidence on biomarkers associated with cognitive impairment (CI) in Post-Traumatic Stress Disorder (PTSD).

Methods
A systematic literature search was conducted for studies assessing biomarkers associated with CI in PTSD.

Results
Of the 10,149 titles screened, 8 studies met our inclusion criteria. In a single longitudinal study, MRI volumes, Aβ and tau accumulation were not associated with CI in PTSD. Studies on structural imaging reported no significant association between morphological changes and CI. Two studies on diffusion neuroimaging showed abnormalities in white matter tracts which were cross-sectionally associated with CI in PTSD. Similarly, lower resting-state functional connectivity in neocortical networks, and elevated tau in the neocortex were also cross sectionally associated with CI. Two single studies on biochemical biomarkers showed that sixteen novel plasma proteins and lower BDNF, indicative of genetic vulnerabilities associated with neural and synaptic dysfunctions commonly observed in neurodegeneration, were cross-sectionally associated with CI in PTSD. Overall, evidence is of low quality.

Conclusions
Longitudinal research utilizing large representative samples of trauma exposed populations are needed to establish the utility of specific biomarkers in monitoring cognitive decline in PTSD.

Highlights

•  A systematic review on biomarkers of cognitive impairment (CI) in PTSD was conducted; 8 studies met inclusion criteria.

•  Despite their potential importance, no biomarker has as yet been validated.

•  In a single longitudinal study identified, MRI volumes, Aβ and tau accumulation were not associated with CI in PTSD.

•  Diffusion neuroimaging showed abnormalities in white matter tracts which were cross-sectionally associated with CI in PTSD.

•  This paper provides clear recommendations on how to overcome the current issues in this research field.