Topic: Genetics and APOE
The apolipoprotein E (apoE) gene has been implicated in various conditions, most notably Alzheimer's disease and coronary artery disease. A predisposing role of the apoE4 isoform and a protective role of apoE2 isoform in those diseases have been documented. Here we investigated the role of apoE in resilience to trauma. Three hundred and forty-three US veterans were genotyped for apoE and were assessed for their lifetime trauma exposure (trauma score, T) and severity of posttraumatic stress disorder symptoms (PCL). The ratio PCL/T indicates sensitivity to trauma; hence, its inverse indicates resilience, R, to trauma. We found a significantly higher resilience in participants with apoE genotype containing the E2 allele (E2/2, E2/3) as compared to participants with the E4 allele (E4/4, E4/3). In addition, when the categorical apoE genotype was reexpressed as the number of cysteine residues per apoE mole (CysR/mole), a highly significant positive association was found between resilience and CysR/mole, such that resilience was systematically higher as the number of CysR/mole increased, from zero CysR/mole in E4/4 to four CysR/mole in E2/2. These findings demonstrate the protective role of the CysR/mole apoE in resilience to trauma: the more CysR/mole, the higher the resilience. Thus, they are in accord with other findings pointing to a generally protective role of increasing number of CysR/mole (from E4/4 to E2/2) in other diseases. However, unlike other conditions (e.g., Alzheimer's disease and coronary artery disease), resilience to trauma is not a disease but an adaptive response to trauma. Therefore, the effects of apoE seem to be more pervasive along the CysR/mole continuum, most probably reflecting underlying effects on brain synchronicity and its variability that we have documented previously (Leuthold et al., Exp Brain Res 226:525-536, 2013).
Key findings
- We found a significantly higher resilience in participants with apoE genotype containing the E2 allele (E2/2, E2/3) as compared to participants with the E4 allele (E4/4, E4/3).
- In addition, when the categorical apoE genotype was reexpressed as the number of cysteine residues per apoE mole (CysR/mole), a highly significant positive association was found between resilience and CysR/mole, such that resilience was systematically higher as the number of CysR/mole increased, from zero CysR/mole in E4/4 to four CysR/mole in E2/2.
- These findings demonstrate the protective role of the CysR/mole apoE in resilience to trauma: the more CysR/mole, the higher the resilience.
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Study details
- Evidence strengthLow
How this study scored 39/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record, multi-centre collaboration and free to read, so those were left out: it earned 22 of the 56 points we could judge it on, which is 39 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Experimental brain research) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 2 / 5 | 2017 — within 10 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 28299413) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 22 / 56 | Scored on 10 of 20 parts. We have no data for the rest, so they are left out: 22 of the 56 points we could judge it on is 39 out of 100. |
| Total | 39 / 100 | — |
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APA 7th
James, L. M., Engdahl, B. E., & Georgopoulos, A. P. (2017). Apolipoprotein E: the resilience gene. Experimental brain research. https://doi.org/10.1007/s00221-017-4941-4
Vancouver
James LM, Engdahl BE, Georgopoulos AP. Apolipoprotein E: the resilience gene. Experimental brain research. 2017. doi:10.1007/s00221-017-4941-4. PMID: 28299413.
BibTeX
@article{james2017-28299413,
author = {James, Lisa M and Engdahl, Brian E and Georgopoulos, Apostolos P},
title = {{Apolipoprotein E: the resilience gene}},
journal = {Experimental brain research},
year = {2017},
doi = {10.1007/s00221-017-4941-4},
pmid = {28299413},
url = {https://doi.org/10.1007/s00221-017-4941-4}
}