Participants and Procedure
-Participants consisted of 63 African American and Caucasian men and women between the ages of 30-64 (at baseline) who were recruited as part of a larger study examining Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS).
-Participants were recruited from thirteen Baltimore city neighborhoods between 2004 and 2008, based on income (125% below or above the poverty line), race (African American or Caucasian), and age (between 30 and 64 years).
-Data for the HANDLS study was collected across 3 waves spanning a time period of approximately 9 years.
-Data for the current study focused on the 21 HANDLS participants who reported Intimate Partner Violence (IPV) victimization in wave 3, but reported no history of IPV victimization prior to their participation in wave 1.
-The initial sample meeting these criteria consisted of 24 participants, but because of missing data, the effective sample size was 21, in addition to 42 matched controls.
-Within the effective sample, 48% of participants identified as female and 52% identified as male. Further, 63% of participants identified as African American and 37% identified as Caucasian.
-Participants received monetary compensation, as well as comprehensive physical examinations, for their participation in the study.
-Informed consent was obtained for each participant prior to his or her participation in the study.
-Demographic information was obtained from each HANDLS participant during an interview conducted in the participants’ home. On a separate occasion, participants were administered various medical and psychological tests during an all-day appointment on a mobile research vehicle (MRV). Detailed information regarding each participant’s medical history was also obtained.
-Although a number of measures were administered, only the data from the measures related to intimate partner violence and cognitive function were analyzed for the current study.
-Detailed information regarding the procedure for the HANDLS study has been described in previous studies (e.g., Evans et al., 2010).
Measures
Demographic information
-Demographic information was obtained during an in-person interview at the participant’s home prior to their participation in medical or psychological testing..
Trail Making Test (TMT) Part A
-Part A of the TMT consists of a sheet of paper displaying circles labeled “1” through “25”.
-This task requires the participant to sequentially connect the 25 circles as quickly and as accurately as possible by drawing straight lines from one circle to the next (e.g., connect circle “1” to circle “2” and so on).
-Studies suggest that part A of the TMT is a valid measure of visuoperceptual abilities.
-Scores are derived from the number of seconds it takes the participant to complete each task (AITB, 1944; Lezak, 1995; Reitan, 1992).
Trail Making Test (TMT) Part B
-Part B of the TMT consists of a sheet of paper displaying 25 circles with numbers (“1”-“12”) and letters (“A”-“L”).
-This task requires participants to connect the 25 circles, switching back and forth between numbers and letters (e.g., connect “1” to “A” and “A” to “2” and “2” to “B” and so on) as quickly and accurately as possible.
-This task serves as a measure of processing speed and cognitive flexibility.
-Scores are derived from the number of seconds it takes the participant to complete each task (AITB, 1944; Lezak, 1995; Reitan, 1992).
The Clock Drawing Test (CDT)
-This task is a measure of cognitive function that requires the participant to accurately depict a clock from memory using only a pencil and a blank sheet of paper.
-Participants were given a blank sheet of paper and were asked to draw the “face” of a clock, including the appropriate numbers, and set the time to “10 after 11” by drawing the “hands” of the clock.
-Participants received a maximum of 2 points for correctly drawing the face of the clock, a maximum of 4 points for correctly drawing the numbers in the clock, and a maximum of 4 points for correctly drawing the hands of the clock to read “10 after 11”.
-Research suggests that the CDT taps a wide range of cognitive abilities, including executive function (Shulman, 2000).
The Animal Naming (AN) Task
-This task is a measure of categorical verbal fluency that requires participants to recite the names of as many animals that they can in 60 seconds.
-Participants receive one point for each animal name that they recite. Duplicate and mythical animal names are not counted (Tombaugh, Kozak, & Rees,1999).
The Center for Epidemiological Studies Depression Scale (CES-D)
-The CES-D is a 20-item questionnaire used to assess the presence and frequency of depressive symptoms in the general population.
-Participants are asked to rate their depressive symptoms within the past week using a 4-point Likert scale ranging from “0” (“rarely or none of the time”) to “3” (“most or all of the time”). Scores for this measure range from 0 to 60. Scores greater than 16 are suggestive of clinically significant depressive symptomatology (Radloff, 1977).
Intimate Partner Violence
-Participants were considered part of the Intimate Partner Violence (IPV) group if they reported either sexual or physical abuse by a partner in wave 3, but reported no abuse prior to their participation in wave 1.
-Intimate partner violence in wave 1 was evaluated during each participant’s medical history interview. Intimate partner violence in wave 3 was evaluated using an audio computer-assisted self-interview (ACASI) software composed of various psychological measures.
-Participants’ reports of abuse were based on whether or not they answered yes to either of the following questions: “Since your last HANDLS examination, have you been hit, slapped, kicked, or otherwise physically hurt by (a partner)?" or “Since your last HANDLS examination, has anyone (partner) forced you to have an unwanted sexual act?"
Analyses
-All statistical analyses were performed using the statistical software "R" (R Core Team, 2013).
Matching
-In order to create a control group with similar covariate distributions, 42 participants who did not meet the criteria for the intimate partner violence (IPV) group were matched to the 21 participants who did meet the criteria for the IPV group. Participants were matched on sex, race, and age at baseline.
-The 1:2 matching procedure was performed using the “MatchIt” package (Ho, Imai, King, & Stuart, 2011) in R studio.
-Pearson's Chi-squared test with Yates' continuity correction was used to test differences in sex and race between the IPV group and matched controls.
-A Welch two-sample t-test was used to test differences in age between the IPV group and matched controls.
-No differences were found for sex (X2 = 0.0043, p = 0.948), race (X2 = 1.754, p = 0.185), or age (t(84.229) = 0.3605, p = 0.719) between the IPV group and matched controls.
Regression Models
-Linear mixed model regression analyses were performed for each of the four cognitive tests (i.e., Trail Making Test Part A, Trail Making Test Part B, Animal Naming Test, and Clock Drawing Test) using the “lme4” (Bates, Maechler, Bolker, & Walker, 2014) and “lmerTest” (Kuznetsova, Brockhoff, & Christensen, 2013) packages in R studio.
-Fixed effects and covariates for model 1 include age, sex, race, and history of intimate partner violence.
-Covariates and fixed effects for model 2 include age, sex, race, history of intimate partner violence, and clinically significant depressive symptomatology.
-The variable “age” served a dual purpose as both the age of the participant and the condition of time.
-Random effects for both models include the variation of age within HANDLS id, as well as the subclass assigned to each participant in the matching procedure.
-Backwards elimination was performed for non-significant fixed and random effects.
-P-values were calculated for t-tests based on Satterthwaite’s approximation for denominator degrees of freedom.
-Random effects were tested using log-likelihood ratio tests with one degree of freedom.