RESUMO
OBJECTIVE: Neuroimaging studies have revealed functional abnormalities in the anterior cingulate cortex in posttraumatic stress disorder (PTSD). The goal of this study was to determine whether hyperresponsivity of the dorsal anterior cingulate in PTSD is an acquired characteristic or a familial risk factor. METHOD: Using a case-control twin design, the authors studied combat-exposed veterans with PTSD (N=12) and their identical combat-unexposed co-twins (N=12), as well as combat-exposed veterans without PTSD (N=14) and their identical combat-unexposed co-twins (N=14). Participants underwent functional MRI during completion of the Multi-Source Interference Task, which reliably activates the dorsal anterior cingulate. RESULTS: Combat-exposed veterans with PTSD and their unexposed co-twins had significantly greater activation in the dorsal anterior cingulate and tended to have larger response time difference scores, as compared to combat-exposed veterans without PTSD and their co-twins. Dorsal anterior cingulate activation in the exposed twins was positively correlated with their PTSD symptom severity. Dorsal anterior cingulate activation in the unexposed twins was positively correlated with their combat-exposed co-twins' PTSD symptom severity, but not with depression or alcohol use severity in the combat-exposed co-twins. CONCLUSIONS: Hyperresponsivity in the dorsal anterior cingulate appears to be a familial risk factor for the development of PTSD following psychological trauma.
Assuntos
Atenção/fisiologia , Distúrbios de Guerra/genética , Distúrbios de Guerra/fisiopatologia , Doenças em Gêmeos/genética , Doenças em Gêmeos/fisiopatologia , Giro do Cíngulo/fisiopatologia , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Reconhecimento Visual de Modelos/fisiologia , Resolução de Problemas/fisiologia , Transtornos de Estresse Pós-Traumáticos/genética , Transtornos de Estresse Pós-Traumáticos/fisiopatologia , Guerra do Vietnã , Nível de Alerta/genética , Nível de Alerta/fisiologia , Mapeamento Encefálico , Discriminação Psicológica/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio/fisiologia , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Transtornos de Estresse Pós-Traumáticos/diagnóstico , Transtornos de Estresse Pós-Traumáticos/psicologia , Gêmeos MonozigóticosRESUMO
BACKGROUND: Posttraumatic stress disorder (PTSD) is marked by intrusive, chronic, and distressing memories of highly emotional events. Previous research has highlighted the role of the amygdala and its interactions with the hippocampus in mediating the effect of enhanced memory for emotional information in healthy individuals. As the functional integrity of these regions may be compromised in PTSD, the current study examined the neural correlates of emotional memory in PTSD. METHODS: We used functional magnetic resonance imaging and an event-related subsequent memory recognition paradigm to study amygdala and hippocampus activation in 18 individuals with PTSD and 18 trauma-exposed non-PTSD control participants. RESULTS: Memory enhancement for negative, relative to neutral, pictures was found across all subjects, without significant differences between groups. Relative to the trauma-exposed non-PTSD group, the PTSD group showed exaggerated amygdala activation during the encoding of negative versus neutral pictures. This effect was even more pronounced when the analysis included data from only pictures that were subsequently remembered 1 week later. In the PTSD group, degree of amygdala activation during the encoding of negative versus neutral pictures was positively correlated with hippocampal activation and current PTSD symptom severity. The PTSD group also showed exaggerated hippocampal activation in response to negative pictures that were remembered versus forgotten. Finally, hippocampal activation associated with the successful encoding of negative relative to neutral pictures was significantly greater in the PTSD group. CONCLUSIONS: Exaggerated amygdala activation during the encoding of emotionally negative stimuli in PTSD is related to symptom severity and to hippocampal activation.
