Memory for Nontrauma Related Information in Traumatized Populations

The research reviewed so far would lead one to suspect that individuals with maltreatment histories and/or PTSD might be particularly accurate at remembering trauma-related information. After all, such individuals appear to pay particular attention to trauma-related cues. However, other research points to deficits in memory function in child sexual abuse victims, especially those who have developed PTSD.

Most of the latter research has concerned memory for information that is not trauma-related. For example, Bremner, Vermetten, Afzal, and Vythilingam (2004) investigated differences in verbal declarative memory among women with self-reported child sexual abuse experiences, both with and without PTSD, and a nonmaltreated control group. These authors found that verbal declarative memory deficits were specifically related to PTSD: adults with child sexual abuse histories who had child sexual abuse-related PTSD had worse verbal declarative memory compared to women with child sexual abuse histories without PTSD and to nonabused women without PTSD. No relation was found between development (age at abuse) and memory, but verbal memory deficits were related to child sexual abuse severity and PTSD symptom severity.

Additional lines of research on victims of war-related traumatic events suggest that general and declarative memory is negatively affected by PTSD. Golier, Harvey, Legge, and Yehuda (2006) examined general memory performance using the California Verbal Learning Test (CVLT) in older combat veterans and Holocaust survivors both with and without PTSD as well as nontrauma-exposed controls. The CVLT consists of a series of word lists presented over five trials and was used to examine free recall (after both short and long delays), cued recall, and recognition memory performance. Findings indicated that participants with trauma histories and PTSD demonstrated significantly worse performance on these explicit memory tasks. Specifically, Holocaust survivors with PTSD had significantly lower scores than non-trauma-exposed controls on measures of free recall, cued recall, and recognition memory. Moreover, PTSD Holocaust survivors performed worse than non-PTSD Holocaust survivors in free recall memory. Memory performance for the combat veterans showed similar patterns. Combat veterans with PTSD performed significantly worse than non-trauma-exposed controls on measures of total learning, short-delay free and cued recall, long-delay free and cued recall, and recognition memory. The authors of this study noted that the participants included older adults (mean age = 69 years) and that the detrimental effects of PTSD on memory may have been greater and more generalized than those typically seen in younger PTSD patients. It is unknown to what extent the effects were related to age or to the chronicity (i.e., duration) of PTSD, or even to childhood trauma experiences as precursors to PTSD.

Research employing other measures of general memory functioning has found similar deficits in verbal and nonverbal memory performance in adult participants with PTSD compared to trauma-exposed participants without PTSD (e.g., Uddo, Vasterling, Brailey, & Sutker, 1993; Vast-erling, Brailey, Constans, & Sutker, 1998), and to non-trauma-exposed controls (e.g., Jelinek et al., 2006). Furthermore, Yasik, Saigh, Oberfield, and Halamandaris (2007) reported similar findings with children. In this study, compared to children exposed to trauma but without PTSD and non-trauma-exposed control participants, children with PTSD performed worse on a measure of general memory functioning (i.e., the Wide Range Assessment of Memory and Learning; Sheslow & Adams, 1990), thus replicating the relation between general memory impairment and PTSD reported in the adult literature. Taken together, these findings from the developmental and the adult literature suggest a specific association between memory impairment and PTSD rather than between memory impairment and trauma exposure in the absence of PTSD

However, research using the Deese/Roediger-McDermott (DRM) paradigm (Deese, 1959; Roediger & McDermott, 1995) provides evidence of memory deficits for neutral stimuli in trauma victims with

PTSD as well as without PTSD. The DRM task produces false memories for words in adults and children (e.g., Brainerd, Reyna, & Forrest, 2002; Ghetti, Qin, & Goodman, 2002). The task involves presenting a list of semantically related words (e.g., bed, rest, awake, tired, dream, wake, snooze, blanket, doze, slumber), all of which are associates of a critical lure (e.g., sleep) that is not presented. On a subsequent memory task, participants will often falsely remember the critical lure as having been presented. When adults are asked if they had a vivid feeling of remembering the critical lure or if they had a less distinctive feeling of familiarity, they often report the former (i.e., report the word as having been previously presented).

Zoellner, Foa, Brigidi, and Przeworski (2002) investigated the susceptibility of trauma victims to false memories on the DRM task. In this study, adult sexual and nonsexual assault victims with and without PTSD were compared to controls using the standard DRM paradigm. Trauma victims with and without PTSD produced more false memories of the critical lure in comparison to controls. In addition, participants with PTSD falsely recalled significantly more critical lures than did both the trauma victims without PTSD and the control group.

Bremner, Shobe, and Kihlstrom (2000) found similar DRM memory impairments with adult victims of child sexual abuse. However, their findings again implicate PTSD more than trauma exposure. Women with self-reported histories of child sexual abuse and PTSD had significantly higher levels of false recognition rates for the critical lure in comparison to participants with self-reported child sexual abuse histories and no PTSD and control participants. In fact, women with PTSD falsely recognized the critical lure more often than they correctly recognized studied words. These findings suggest that women who develop PTSD subsequent to child sexual abuse are more prone to memory distortions and illusions compared to those who did not develop PTSD. Possible explanations of these results are that these women are more dissociative, or that they suffered hippocampal damage, as indicated by previous research on PTSD (Bremner, 1999). Although these findings have been used to support claims that women with abuse histories and PTSD may be particularly susceptible to false memories in general, the word lists used in this study were relatively neutral. Research investigating DRM memory for trauma-related word lists in abuse populations with and without PTSD is needed.

Developmental researchers recently examined false memory in maltreated children (Howe, Cicchetti, Toth, & Cerrito, 2004). After presentation of standard DRM word lists, which contain mainly neutral, nontrauma-related themes, children ages 5 to 7 or 10 to 12 years produced false memories on both recall and recognition memory tests. Of particular interest, no difference was observed in false memory performance between maltreated and nonmaltreated children. This study is important because it was the first to examine DRM false memory in maltreated versus nonmaltreated youth. It is possible, however, that the effects of trauma on memory processes could take time to develop and therefore may not be evident until adolescence or young adulthood. In addition, inclusion of measures of trauma-related psychopathology (e.g., PTSD, dissociation) and trauma-related DRM lists would be of interest as an addition to this type of study. Similar to research described above with adults, memory deficits observed with children on the DRM task using neutral word lists may not generalize to memory for trauma-related information.

The research reviewed in this section indicates that traumatized adults typically perform worse on standardized and laboratory memory tests than nontraumatized adults when the "to-be- remembered" information is neutral. However, not all investigations of general memory functioning have uncovered differences between individuals with PTSD and controls (e.g., Beers & DeBellis, 2002; Jenkins, Langlais, Delis, & Cohen, 2000). In addition, research described in the previous section of this chapter indicated that traumatized individuals pay more attention to trauma-related information and at times evince better memory, or at least equally accurate memory, for such information, compared to nontraumatized controls. This research shows that trauma victims attend to and remember trauma-related information relatively well. If so, trauma victims might have particularly accurate autobiographical memory for trauma-related events in their lives. Of note, for some child victims, their childhoods in general are trauma-related.

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