Transcript Document
Do personality traits contribute to resiliency to brain pathology? Sarah Tomaszewski Farias, Maritza Dowling, Dan Mungas, Bruce Reed, Joshua Sonnen, Milton Strauss Conceptual Approach Conceptually, reserve explains deviations from the level of cognitive performance that would be expected for a given amount of brain pathology Methodological approach: we modeled reserve as residual cognition after accounting for neuropathology (and brain weight?) and then we examined variables that account for this residual Personality trait examined: Neuroticism/distress proneness/negative affectivity and trait anxiety Rationale Chronic reaction to threat triggers overactivation of the HPA axis and the release of stress hormones (i.e. glucocorticoids, particularly cortisol) It is hypothesized that chronic exposure to cortisol increases excitatory amino acid release, resulting in neuronal injury The hippocampus is particularly vulnerable to such effects since it has a high density of glucocorticoid receptors Hippocampal atrophy has been associated with PTSD and other chronic psychiatric syndromes Elevated basal cortisol is associated with hippocampal atrophy (in pts with AD) Frontal systems (particularly anterior cingulate) have also been implicated Conceptual Model Npath 1 Npath 2 Npath 3 Education Cognitive factor Residual/ reserve Distress Proneness Cognitive Activity Cog 1 Cog2 Cog 3 Cog4 Cog5 Cog 6 Data Sources Rush Memory Assessment Project (MAP) and ROS Similar to previous studies presented Distress proneness variable Recall that Neuroticism was defined as the total score obtained in the following FIVE items (common to both ROS and MAP): Variable # Variable Name Question v2 inferior ------I often feel inferior to others v3 tense--------- I often feel tense and jittery v4 getangry -----I often get angry at the way people treat me v5 discourg------Too often, when things go wrong, I get discouraged and feel like giving up v6 helpless-------I often feel helpless and want someone else to solve my problems Trait Anxiety Variable The trait anxiety construct included the following 10 items common to both MAP & ROS Question: For the next statements, circle Y for YES if it describes how you generally feel or N for NO if it does not describe how you generally feel. 1. I feel pleasant. 2. I feel nervous and restless 3. I wish I could be as happy as others seem to be. 4. I feel that difficulties are piling up so that I cannot overcome them. 5. I lack self-confidence. 6. I feel secure. 7. I feel inadequate. 8. I am content. 10. I take disappointments so keenly that I can t put them out of my mind. Coding: Integer 1 = Yes 2 = No 8 = REFUSAL 9 = DON'T KNOW The Reliability index (Omega) is 0.927252 Distress proneness on residual NOTE – THE CORRELATION BETWEEN NEUOTICISM & TRAIT ANXIETY IS 0.578 FIRST, I EXAMINED EFFECTS OF NEUROTICISM & ANXIETY SEPARATELY. TESTS OF MODEL FIT Chi-Square Test of Model Fit Value Degrees of Freedom P-Value Scaling Correction Factor for MLR Value Degrees of Freedom P-Value 1421.795* 596 0.0000 1.028 14267.244 726 0.0000 CFI/TLI CFI TLI 0.939 0.926 RMSEA (Root Mean Square Error Of Approximation) Estimate 90 Percent C.I. Probability RMSEA <= .05 0.046 0.043 0.982 SRMR (Standardized Root Mean Square Residual) Value 0.038 0.049 Distress proneness on residual RES ON NEUTICNW -0.077 0.018 -4.327 0.000**** The R2 with Neuroticism as covariate is Latent Variable EPISR SEMR WMR PSPR PORGR FLR RES Estimate 0.738 0.678 0.848 0.803 0.818 0.765 0.049 S.E. 0.038 0.056 0.033 0.034 0.065 0.031 0.023 Est./S.E. 19.304 12.144 25.725 23.892 12.563 24.574 2.140 Two-Tailed P-Value 0.000 0.000 0.000 0.000 0.000 0.000 0.032** Trait Anxiety on residual RES ON TRTANX2 -0.175 0.058 -3.013 0.003** The R2 with trait anxiety as a covariate is Latent Variable EPISR SEMR WMR PSPR PORGR FLR RES Estimate S.E. 0.739 0.679 0.849 0.802 0.817 0.766 0.031 0.038 0.056 0.033 0.034 0.065 0.031 0.020 Two-Tailed Est./S.E. P-Value 19.364 12.157 25.689 23.697 12.530 24.658 1.506 0.000 0.000 0.000 0.000 0.000 0.000 0.132 ns Model with both Distress Proneness and Trait Anxiety RES ON NEUTICNW TRTANX2 -0.172 -0.089 0.062 0.067 Latent Variable RES Estimate 0.055 S.E. 0.025 -2.766 -1.322 0.006**** 0.186 ns R^2 Two-Tailed Est./S.E. P-Value 2.206 0.027** Other variables to consider We also examined social engagement and size of social network – neither alone or in a joint model accounted for significant variance in the residual term (trend of social engagement in individual model p = .068) It may be possible to examine physical activity – but the variable we appear to have is only ‘current’ physical activity (not retrospective ratings of earlier life activity) and variable is highly skewed Remaining questions Previous work by the Rush group suggests that distress proneness does not relate to traditional neuropathology of aging variables (amyloid, tangels, LBs, infarcts) – Other evidence suggests chronic distress may lead to nonspecific changes such as decreased dendritic arborization – Should we look at a model that does not include brain weight (which may reflect these nonspecific changes)? Other work from the Rush group suggest that distress proneness may have differential effects on different cognitive domains (episodic memory) – Should we look separately at the residual terms for specific cognitive domains?