Depression and hippocampal volume in the aging brain: an epidemiological investigation
Notice bibliographique
Résumé
Background: Magnetic resonance imaging (MRI) studies have reported that patients with depression have smaller hippocampal volume (HcV) than healthy controls. However, the temporality of this association is unresolved. Two main hypotheses are proposed to explain the depression-HcV relationship. The neurotoxicity hypothesis suggests that HcV atrophy results from biological and neurochemical alterations that accompany depression and stress; an alternative hypothesis is that reduced HcV could be a susceptibility factor for depression. Disentangling the temporality of the depression-HcV atrophy relationship is of particular interest in older adults as it can help unravel the complex processes underlying aging-related cerebral, cognitive, and mood changes. Research objectives: The overall aim of this thesis was to examine the two main hypotheses on the temporal relationship between depression and HcV atrophy in a population-based sample of older adults; the specific objectives were: 1) To assess whether history of previous depression and more proximal depressive symptoms are related to HcV atrophy; 2) To estimate the association between life-course socioeconomic position (SEP), as a proxy for increased stress, and HcV atrophy; 3) To examine whether HcV atrophy is associated with subsequent depressive symptoms. Study population: Data come from the Three-City-Dijon-MRI cohort, a prospective population-based French cohort of older adults (n=1328, age=65-80 years) who were followed biennially for over ten years and who had two cerebral MRI scans, at baseline and four-year follow-up. Manuscript 1- Examining the neurotoxicity hypothesis: We estimated the association between history of previous depression and proximal depressive symptoms (Center for Epidemiologic Studies-Depression (CES-D) scale) and both baseline HcV and rate of HcV atrophy. We found that baseline depressive symptoms were associated with smaller HcV in women; in contrast, history of depression and more proximal depressive symptoms were associated with faster HcV atrophy in women but not in men. Our findings also showed that treatment for depression was associated with slower HcV atrophy in men and women. Manuscript 2- Life-course SEP and HcV atrophy: To further explore the neurotoxicity hypothesis and its implication that stressful conditions may contribute to HcV atrophy, we examined the relationships of SEP with HcV and HcV atrophy using three life-course SEP models: (i) the sensitive/critical-period model which focused on SEP at three periods over the life-course: childhood SEP (parental education), early-adulthood SEP (participants’ education), and mid-life SEP (participants’ socioprofessional attainment); (ii) life-course cumulative SEP; and (iii) social-mobility of life-course SEP trajectories. Childhood and early-adulthood SEP were not related to HcV outcomes. Participants with lower socioprofessional attainment in mid-life had smaller HcV and faster HcV atrophy. Results also suggested that cumulative low SEP and disadvantageous SEP trajectories over the life-course were associated with faster HcV atrophy. Manuscript 3- Exploring the hypothesis that HcV atrophy is a susceptibility factor for depression: We used linear mixed-models to estimate the associations between rate of HcV atrophy and (i) average-over-follow-up depressive symptoms (CES-D scores) measured biennially over the subsequent six years and (ii) change in depressive symptoms. Results indicated that, in women, faster HcV atrophy was associated with more average over-follow-up depressive symptoms and with worsening of symptoms over the two subsequent years. No association was detected in men. Conclusion: Our findings suggest a complex and bi-directional relationship between HcV atrophy and depressive symptoms in women but not in men. The results also highlight the role for stress-related experiences (previous depression and lower SEP) in explaining some of the variability in HcV atrophy at older age.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,002 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».