Table 2.

Possible biomarkers linking post-traumatic stress disorder and neurodegeneration.

Biomarker Type	Level of Evidence
Brain imaging
Reduced cortical thickness	++
Reduced volume of specific right cortical regions	++
Reduced white matter tract integrity	++
Reduced structural grey matter connectivity	+
Reduced right hippocampal volume	±
Increased amygdalar volume	?
Increased BOLD variability in the basal forebrain	?
Genetic and epigenetic
Association between ALOX12 SNPs and reduced right prefrontal volume	+
Association between GC SNPs and PTSD risk	+
Upregulation of FKBP5, REST, SEPT4 in leukocytes	+
miR-139-5p	+
Reduced telomere length	?
Post-mortem expression of COL6A3, GCNT1, GPRIN3 in brain	?
Biochemical
Reduced serum total vitamin D	+
Increased rate of metabolic syndrome	+
Elevated peripheral NfL	±
Reduced peripheral Aβ 42/40 ratio	±
Immune-inflammatory
Serum CRP	+
Serum sTNF-RII	+
CSF IL-6	+
Sleep-related
Increased rates of RSBD or dream enactment behavior	++
Increased REM sleep with atonia	+

Key: ++, positive evidence from more than one study; +, positive evidence from a single study; ±, conflicting results; ?, positive results only in sub-group analyses or results of uncertain significance.