1. The Influence of Dispositional Mindfulness on Inhibitory Capacity in a Trauma-Exposed Sample
Tina Wang1, Carolyn Davies, M.A.1, Lisa Burklund, Ph.D. 1,2, Jared Torre1,
Matthew Lieberman, Ph.D. 1, Michelle Craske, Ph.D. 1
1University of California Los Angeles; 2Defense Group Inc.
INTRODUCTION
RESULTS: LEVELS OF MINDFULNESS (BETWEEN SUBJECTS)
PARTICIPANTS
Do veterans with PTSD exhibit reduced dispositional mindfulness and impaired response inhibition compared to veterans without PTSD?
Does dispositional mindfulness affect performance-based inhibitory control, such that greater mindfulness is associated with faster reaction times and less error rates?
Veterans with PTSD (n=18)
17 males, 1 female
Mean age = (range: years)
Trauma-exposed healthy controls (n=20)
16 males, 4 females
Mean age = (range: years)
Ethnicity:
42.1% Hispanic/Latino
26.3% White/Caucasian
13.2% Mixed Race
10.5% Asian/Pacific Islander
7.9% Black/African-American
All participants were recruited from the Greater Los Angeles County
t(33)=2.42, p=0.02
t(33)=2.66, p=0.01
PTSD patients showed a significant deficit in response inhibition, committing more errors on NoGo trials than controls (Swick et al. 2012).
The inability of patients with PTSD to inhibit intrusion of traumatic recollections aggravates psychomotor slowness, increases number of errors, and impairs Stroop performance (Kertzman et al. 2014).
In trauma-exposed individuals, those with relatively high levels of mindfulness skills tend to have lower levels of symptoms (Schoorl, Mil-Klinkenberg, & Van Der Does 2014), such that there are reductions in avoidance (Kumar et al. 2008; Lykins and Baer 2009) and fewer difficulties with emotion regulation (Vujanovic et al. 2010).
RESULTS: GO REACTION TIMES (BETWEEN SUBJECTS)
F(3, 31) = 1.490, p = .236, R2 = .126
RESULTS: REGRESSION TABLES
Higher levels of dispositional mindfulness are also associated with performance on measures of cognitive control, such as inhibitory control in young adults (Anicha, Ode, Moeller, & Robinson, 2012).
Table 1. Regression results for MAAS and Group as a predictor of GO trial reaction times
Unstandardized Beta
Standardized Beta
p-value
Group
0.009
0.063
0.930
MAAS
0.002
0.031
0.911
MAASxGroup
-0.010
-0.244
0.712
Table 2. Regression results for MAAS and Group as a predictor of NOGO trial error rates
-0.195
-0.025
0.972
0.124
0.033
0.904
0.169
0.075
Table 3. Regression results for KIMS and Group as a predictor of GO trial reaction times
0.271
1.898
0.134
KIMS - Describe Subscale
0.483
0.109
KIMSxGroup
-0.011
-1.959
0.102
Table 4. Regression results for KIMS and Group as a predictor of NOGO trial error rates
1.104
0.137
0.917
-0.125
-0.122
0.695
-0.073
-0.22
0.859
Hypothesis: Veterans with PTSD would have lower levels of dispositional mindfulness, and lower mindfulness scores would be associated with slower reaction times and higher error rates on the Go-NoGo task, above and beyond diagnostic category.
SURVEY MEASURES
F(3, 30) = .380, p =.768, R2 = .037
Kentucky Inventory of Mindfulness Skills (KIMS)-Describe Subscale
8 items, 5-point likert scale
Self-report inventory that is used to assess mindfulness skills, with higher scores reflecting more mindfulness
Sample item:
I can easily put my beliefs, opinions, and expectations into words.
never or very rarely true – (5) almost always or always true
Mindful Attention Awareness Scale (MAAS)
15 items, 6-point likert scale
Self-report inventory that is used to assess a sensitive awareness of the present (a core characteristic of mindfulness), with higher scores reflecting higher levels of mindfulness disposition
I could be experiencing some emotion and not be conscious of it until some time later. (1) almost always – (6) almost never
RESULTS: NOGO ERROR RATES (BETWEEN SUBJECTS)
DISCUSSION
F(3, 31) = .267, p = .848, R2 = .025
Summary
Consistent with hypothesis, healthy control veterans had greater dispositional mindfulness compared to those with PTSD.
Go-NoGo results did not support our hypothesis: There was no effect of group or mindfulness scores on Go-NoGo performance, suggesting that those individuals with more dispositional mindfulness did not exhibit better inhibitory control or less impulsive behavior.
Limitations
Small sample size and use of a non-emotional Go-NoGo task
Future Directions
Examine the effect of dispositional mindfulness on performance during a threat-related behavioral response task with larger sample groups.
GO-NOGO MOTOR INHIBITION TASK
Participants are asked to press a button each time they see one particular letter (Go trials) and not press the button when they see any other letter (NoGo trials)
Go trials occur approximately 80% of the time and NoGo trials the remaining 20% of trials (300 trials total per participant)
The number of button presses on NoGo trials will provide a behavioral index of inhibitory errors
F(3, 30) = .038, p =.990, R2 = .004