Genetic and environmental risk factors for post-traumatic stress disorder after the 1999 earthquakes in Taiwan:indings from an aboriginal community
Date Issued
2008
Date
2008
Author(s)
Lee, Chau-Shoun
Abstract
Background: Posttraumatic stress disorder (PTSD) is a common mental disorder in response to an identifiable traumatic event. This diagnostic category contains a constellation of symptoms, including re-experiencing, avoidance and numbed responsiveness, and symptoms of increased arousal. Traumas are often classified as natural and man-made. Although the characteristics of a trauma have been shown to influence the risk of PTSD, only 27.8% of such risk was significantly attributable to the trauma exposure itself. Individual vulnerability and pre- and post-trauma situations are also important pathogenic factors in the development of PTSD. It is therefore important to examine the relative weight of environmental factors versus genetic vulnerability. This study investigates PTSD in one Taiwanese aboriginal group (the Bunun) exposed to a severe earthquake disaster. The earthquake shook central Taiwan at 01:47:15 am on September 21, 1999 local time, measuring 7.3 on the Richter scale, the strongest one among several earthquakes over the past one hundred years in Taiwan. Study subjects came from a cohort of the Bunun established in 1987-88 in a longitudinal study of mental disorders among four major aboriginal groups in Taiwan. They were randomly selected from four villages in Hsingyi County located in the central mountain region of Taiwan; happen to be close to the epicenter of the 9-21 earthquakes (about 18 kilometers away), and has thus provided an excellent opportunity for studying PTSD. ethodology: Respondents (n=196) were assessed 5 months after the earthquake. Information regarding the magnitude of the 9-21 earthquakes was obtained from the website of the Seismological Center, Central Weather Bureau in Taiwan. The local area where our study subjects resided was under 7.3 in Richter scale. Different Richter scales encountered by study subjects who stayed in other areas during the earthquakes were checked individually. A five-item questionnaire was designed to measure the extent of traumas from the earthquakes, using the Likert-type scoring system. Psychiatric diagnoses were performed by five senior psychiatrists, using a Chinese version of the WHO Schedules for Clinical Assessment in Neuropsychiatry. The degree of acculturation was measured using the Taiwan Aboriginal Acculturation Scale. A Chinese version of the List of Threatening Experiences (LTE) was used to assess stressful life events within 6 months prior to the 9-21 earthquakes. For genotypic study, we also prepared DNA using venous blood drawn from study subjects using standard methods. Polymorphisms were examined in the genes which are involved in the serotonin, dopamine, opioid, and GABA pathways. esults: A majority of respondents (n=163, 83.2%) encountered with higher degrees of shaking (159 with 7.3 and 4 with 6 in Richter scale). According to DSM-IV criteria, a total of 76 subjects (38.8%) were diagnosed as having suffered from PTSD related to the 921 earthquakes. There were much higher rates of antecedent psychiatric disorders, including alcohol use disorders (59.7%), generalized anxiety disorder (34.7%), major depressive disorder (26.0%), and panic disorder (6.1%). Four environmental and psychiatric risk factors exerted independent effect on the risk of PTSD, including magnitude of the earthquake, subsequent traumas, antecedent major depressive disorder and acculturation status. Five single nucleotide polymorphisms (SNPs) played significant effects on the risk of PTSD, including DRD2-rs11214607 in the dopamine system, KOR-rs16918928 in the opiod system, GABRB2-rs6881515 in the GABA system and TPH-rs1843811 and TPH-rs172423 in the serotonin system. Joint effects of genetic and environmental factors were further examined. Risk factors still with independent main effects were degree of the earthquake exposure, its subsequent trauma, major depressive disorder, GABRB2- rs6881515, TPH-rs1843811, and DRD2-rs11214607. Significant two-way interactions include KOR-rs16918928 and magnitude of quake (Ritcher scale), as well as TPH-rs172423 and magnitude of quake.onclusions: Public mental health programs need to consider the liability to PTSD in populations with different ethnicity and socio-cultural environments. Findings in this study suggest that for early detection of PTSD and prompt management, attention should be paid among survivors of natural disasters who exposed to higher extents of the disaster; had higher subsequent traumas; had genetic vulnerability; and had antecedent mental disorders, notably major depressive disorder. For aboriginal populations, further attention should be given to those with a lower extent of acculturation.
Subjects
earthquake
PTSD
acculturation
psychiatric comorbidity
gene
SNP
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-97-D90842008-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):3cc614c53dfa3c566b183e75f802d854