PTSD symptoms and cognitive performance in recent trauma survivors
Introduction
Intrusive recall and partial forgetfulness of the traumatic event are cardinal features of post-traumatic stress disorder (PTSD; American Psychiatric Association, 1994). Additionally, the disorder has been associated with subjective complaints of poor concentration and memory (Klonoff et al., 1976, Goldfield et al., 1988, Weiner, 1992, Uddo et al., 1993), and with biased allocation of attention towards threatening stimuli (McNally et al., 1990, Vrana et al., 1995, Semple et al., 1996).
Beyond trauma-related memory, PTSD has been associated with measurable impairment of memory and attention, and with lower IQ (for review, see Wolfe and Schlesinger, 1997, Buckley et al., 2000). Studies to date point to two hypothetical domains of cognitive impairment in PTSD, namely, impaired declarative memory (e.g. Bremner et al., 1993, Bremner et al., 1995) and impaired attention and working memory (e.g. Uddo et al., 1993, Vasterling et al., 1998).
Specifically, Bremner et al. (1993) found poorer immediate and delayed verbal memory in 26 Vietnam veterans with PTSD compared with 15 healthy controls. Bremner et al. (1995) found poorer immediate and delayed verbal memory among 21 survivors of childhood abuse with PTSD, compared to 20 matched controls. Significant correlation between verbal memory and trauma severity was found in both studies. Yehuda et al. (1995) found higher proactive interference with memory acquisition in PTSD. Uddo et al. (1993), who examined 16 PTSD Vietnam veterans and 15 regular soldiers with no history of trauma, found impaired learning, perseverative errors, poorer word fluency and impaired immediate visual memory among PTSD patients. Vasterling et al. (1998) showed deficiencies in sustained attention, mental manipulation, acquisition of new information, retroactive interference, and errors of commission and intrusion in 19 Gulf War veterans with PTSD compared with 24 mentally healthy veterans.
Findings of cognitive deficits in PTSD may reveal the involvement of specific brain areas in this disorder. Accordingly, impaired declarative memory has been attributed to hippocampal dysfunction, which in PTSD may reflect a damaging effect of chronic stress on hippocampal cells (e.g. Bremner et al., 1995, McEwen, 2000). Deficits in attention and working memory have been interpreted as suggesting an involvement of the prefrontal lobes (e.g. Vasterling et al., 1998). Specific anatomical allocations, however, may not reflect the complexity and interconnectedness of the neural systems that sub-serve memory and attention.
Previous cognitive studies concerned chronic PTSD. As such, they could not reveal the origin of their findings. Cognitive impairments may precede the onset of PTSD, or develop along with the disorder. The former hypothesis received indirect support from studies showing lower pre-military IQ in Vietnam veterans who developed PTSD (e.g. Macklin et al., 1998). A hypothetical deficiency of declarative memory, at the early aftermath of a traumatic event, may result from stress-induced hormonal inhibition of hippocampal functions (e.g. McEwen, 2000).
Exploring the association between early PTSD symptoms and cognitive impairment is compelling. Subjects who express high levels of PTSD symptoms in the early aftermath of traumatic events are at higher risk for developing PTSD (e.g. Shalev et al., 1997). A cognitive impairment may contribute to this link: cognitive deficits may interfere with recovery from mental trauma, a process that requires re-learning and adaptation (Shalev, 2000). Early cognitive deficits may also lead to impaired acquisition of traumatic memories. In contrast, the absence of early cognitive dysfunction, among symptomatic survivors, will suggest that cognitive impairments develop along with PTSD.
This study evaluated the link between PTSD symptoms and cognitive functioning, 10 days after a traumatic event. At such time, a formal diagnosis of PTSD cannot be made, yet some survivors already express high levels of PTSD symptoms whereas others do not. The study evaluated attention, learning, memory and IQ, as well as symptoms of depression, dissociation and anxiety. The latter were used to probe the specificity of the hypothesised association between early PTSD symptoms and cognitive dysfunction.
Section snippets
Subjects
Forty-eight survivors (28 women and 20 men) were recruited, by telephone, within 10 days of their release from an emergency room of a large public hospital in Jerusalem following a traumatic event. The traumatic events consisted of 37 motor vehicle accidents, five terror attacks, three physical assaults, two home or work accidents and one rape. Survivors whose age was between 20 and 55 and whose traumatic events met DSM-IV PTSD criterion ‘A’ (exposure and intense response) were invited to
Results
The study groups had similar age, gender, type of traumatic event and STAI-trait scores (Table 1). Subjects with high levels of PTSD symptoms had lower level of education and higher STAI-state, BDI and PDEQ scores.
Subjects with high levels of PTSD symptoms had lower scores on figural memory (immediate and delayed recall) and lower IQ (Table 2). The groups, however, had similar percent retention of figural memory.
Subjects with high levels of PTSD symptoms also showed poorer attention (digit
Discussion
The results of this study show that individuals who express high levels of early PTSD symptoms have poorer attention and lower IQ. The results of this study do not show an association between early PTSD symptoms and either learning or verbal memory. Additionally, this study shows that poorly acquired information is normally retained by subjects with high levels of PTSD symptoms (i.e. the groups showed similar percents of retention). This finding suggests that attentional difficulties may affect
Acknowledgments
This study was supported by PHS research grant no. NH 50374.
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