Low-level cognitive ability in young adulthood and other risk factors of depression in an observational cohort study among deployed Danish soldiers

Lars Ravnborg Nissen*, Karen Inge Karstoft, Mia Sadowa Vedtofte, Anni Brit Sternhagen Nielsen, Merete Osler, Erik Lykke Mortensen, Gunhild Tidemann Christensen, Søren Bo Andersen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Purpose: Evidence exists of an association between pre-morbid lower cognitive ability and higher risk of hospitalization for depressive disorder in civilian cohorts. The purpose of this study was to examine the relationship of cognitive ability at conscription with post-deployment depression and the influence of (1) baseline factors: age, gender, and pre-deployment educational level, (2) deployment-related factors: e.g., war-zone stress and social support, and (3) co-morbid PTSD. 

Methods: An observational cohort study linking conscription board registry data with post-deployment self-report data. The study population consisted of Danish Army military personnel deployed to different war zones from 1997 to 2015. The association between cognitive ability at conscription and post-deployment depression was analyzed using repeated-measure logistic regression models. 

Results: Study population totaled 9716 with a total of 13,371 deployments. Low-level cognitive ability at conscription was found to be weakly associated with post-deployment probable depression after adjustment for more important risk factors like gender, education, and deployment-related factors [odds ratio (OR) 0.93, 95% confidence interval (CI) 0.88–0.99]. The co-occurrence rate with PTSD was nearly 60%. When adding co-morbid PTSD as an independent variable, the association between cognitive ability and probable depression became insignificant, OR 0.95, CI 0.89–1.02. 

Conclusions: Low cognitive ability at conscription is a risk factor for depression among returning military personnel, but unimportant compared to gender, education, and deployment-related factors. Part of this effect may be related to co-morbid PTSD. Use of cognitive ability score as an isolated selection tool cannot be recommended because of low predictive performance.

Original languageEnglish
JournalSocial Psychiatry and Psychiatric Epidemiology
Volume54
Issue number4
Pages (from-to)497-506
ISSN0933-7954
DOIs
Publication statusPublished - 3. Apr 2019

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Military Personnel
cognitive ability
soldier
adulthood
Cohort Studies
Depression
Logistic Models
Odds Ratio
Confidence Intervals
Education
gender
personnel
confidence
Military
Age Factors
Self Report
Population
Registries
hospitalization
military

Keywords

  • Cognitive ability
  • Depression
  • Epidemiology
  • Military
  • PTSD

Cite this

Nissen, Lars Ravnborg ; Karstoft, Karen Inge ; Vedtofte, Mia Sadowa ; Nielsen, Anni Brit Sternhagen ; Osler, Merete ; Mortensen, Erik Lykke ; Christensen, Gunhild Tidemann ; Andersen, Søren Bo. / Low-level cognitive ability in young adulthood and other risk factors of depression in an observational cohort study among deployed Danish soldiers. In: Social Psychiatry and Psychiatric Epidemiology. 2019 ; Vol. 54, No. 4. pp. 497-506.
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title = "Low-level cognitive ability in young adulthood and other risk factors of depression in an observational cohort study among deployed Danish soldiers",
abstract = "Purpose: Evidence exists of an association between pre-morbid lower cognitive ability and higher risk of hospitalization for depressive disorder in civilian cohorts. The purpose of this study was to examine the relationship of cognitive ability at conscription with post-deployment depression and the influence of (1) baseline factors: age, gender, and pre-deployment educational level, (2) deployment-related factors: e.g., war-zone stress and social support, and (3) co-morbid PTSD. Methods: An observational cohort study linking conscription board registry data with post-deployment self-report data. The study population consisted of Danish Army military personnel deployed to different war zones from 1997 to 2015. The association between cognitive ability at conscription and post-deployment depression was analyzed using repeated-measure logistic regression models. Results: Study population totaled 9716 with a total of 13,371 deployments. Low-level cognitive ability at conscription was found to be weakly associated with post-deployment probable depression after adjustment for more important risk factors like gender, education, and deployment-related factors [odds ratio (OR) 0.93, 95{\%} confidence interval (CI) 0.88–0.99]. The co-occurrence rate with PTSD was nearly 60{\%}. When adding co-morbid PTSD as an independent variable, the association between cognitive ability and probable depression became insignificant, OR 0.95, CI 0.89–1.02. Conclusions: Low cognitive ability at conscription is a risk factor for depression among returning military personnel, but unimportant compared to gender, education, and deployment-related factors. Part of this effect may be related to co-morbid PTSD. Use of cognitive ability score as an isolated selection tool cannot be recommended because of low predictive performance.",
keywords = "Cognitive ability, Depression, Epidemiology, Military, PTSD",
author = "Nissen, {Lars Ravnborg} and Karstoft, {Karen Inge} and Vedtofte, {Mia Sadowa} and Nielsen, {Anni Brit Sternhagen} and Merete Osler and Mortensen, {Erik Lykke} and Christensen, {Gunhild Tidemann} and Andersen, {S{\o}ren Bo}",
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Low-level cognitive ability in young adulthood and other risk factors of depression in an observational cohort study among deployed Danish soldiers. / Nissen, Lars Ravnborg; Karstoft, Karen Inge; Vedtofte, Mia Sadowa; Nielsen, Anni Brit Sternhagen; Osler, Merete; Mortensen, Erik Lykke; Christensen, Gunhild Tidemann; Andersen, Søren Bo.

In: Social Psychiatry and Psychiatric Epidemiology, Vol. 54, No. 4, 03.04.2019, p. 497-506.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Low-level cognitive ability in young adulthood and other risk factors of depression in an observational cohort study among deployed Danish soldiers

AU - Nissen, Lars Ravnborg

AU - Karstoft, Karen Inge

AU - Vedtofte, Mia Sadowa

AU - Nielsen, Anni Brit Sternhagen

AU - Osler, Merete

AU - Mortensen, Erik Lykke

AU - Christensen, Gunhild Tidemann

AU - Andersen, Søren Bo

PY - 2019/4/3

Y1 - 2019/4/3

N2 - Purpose: Evidence exists of an association between pre-morbid lower cognitive ability and higher risk of hospitalization for depressive disorder in civilian cohorts. The purpose of this study was to examine the relationship of cognitive ability at conscription with post-deployment depression and the influence of (1) baseline factors: age, gender, and pre-deployment educational level, (2) deployment-related factors: e.g., war-zone stress and social support, and (3) co-morbid PTSD. Methods: An observational cohort study linking conscription board registry data with post-deployment self-report data. The study population consisted of Danish Army military personnel deployed to different war zones from 1997 to 2015. The association between cognitive ability at conscription and post-deployment depression was analyzed using repeated-measure logistic regression models. Results: Study population totaled 9716 with a total of 13,371 deployments. Low-level cognitive ability at conscription was found to be weakly associated with post-deployment probable depression after adjustment for more important risk factors like gender, education, and deployment-related factors [odds ratio (OR) 0.93, 95% confidence interval (CI) 0.88–0.99]. The co-occurrence rate with PTSD was nearly 60%. When adding co-morbid PTSD as an independent variable, the association between cognitive ability and probable depression became insignificant, OR 0.95, CI 0.89–1.02. Conclusions: Low cognitive ability at conscription is a risk factor for depression among returning military personnel, but unimportant compared to gender, education, and deployment-related factors. Part of this effect may be related to co-morbid PTSD. Use of cognitive ability score as an isolated selection tool cannot be recommended because of low predictive performance.

AB - Purpose: Evidence exists of an association between pre-morbid lower cognitive ability and higher risk of hospitalization for depressive disorder in civilian cohorts. The purpose of this study was to examine the relationship of cognitive ability at conscription with post-deployment depression and the influence of (1) baseline factors: age, gender, and pre-deployment educational level, (2) deployment-related factors: e.g., war-zone stress and social support, and (3) co-morbid PTSD. Methods: An observational cohort study linking conscription board registry data with post-deployment self-report data. The study population consisted of Danish Army military personnel deployed to different war zones from 1997 to 2015. The association between cognitive ability at conscription and post-deployment depression was analyzed using repeated-measure logistic regression models. Results: Study population totaled 9716 with a total of 13,371 deployments. Low-level cognitive ability at conscription was found to be weakly associated with post-deployment probable depression after adjustment for more important risk factors like gender, education, and deployment-related factors [odds ratio (OR) 0.93, 95% confidence interval (CI) 0.88–0.99]. The co-occurrence rate with PTSD was nearly 60%. When adding co-morbid PTSD as an independent variable, the association between cognitive ability and probable depression became insignificant, OR 0.95, CI 0.89–1.02. Conclusions: Low cognitive ability at conscription is a risk factor for depression among returning military personnel, but unimportant compared to gender, education, and deployment-related factors. Part of this effect may be related to co-morbid PTSD. Use of cognitive ability score as an isolated selection tool cannot be recommended because of low predictive performance.

KW - Cognitive ability

KW - Depression

KW - Epidemiology

KW - Military

KW - PTSD

U2 - 10.1007/s00127-018-1648-1

DO - 10.1007/s00127-018-1648-1

M3 - Journal article

C2 - 30617593

AN - SCOPUS:85059659853

VL - 54

SP - 497

EP - 506

JO - Social Psychiatry and Psychiatric Epidemiology

JF - Social Psychiatry and Psychiatric Epidemiology

SN - 0933-7954

IS - 4

ER -