[ Links ] 2. Middeldorp CM, Cath DC, van Dyck R, Boomsma DI. The co-morbidity of anxiety and depression in the perspective of genetic epidemiology. A review of twin and family studies. Psychol Med. 2005;35(5):611-24. [ Links ] 3. Hettema JM, Neale MC, Myers JM, Prescott CA, Kendler KS. A population-based twin study of the relationship between neuroticism and internalizing disorders. Am J Psychiatry. 2006;163(5):857-64. [ Links ] 4. Harmer CJ, Mackay CE, Reid CB, Cowen PJ, Goodwin GM. Antidepressant drug treatment modifies the neural processing of nonconscious threat cues. Biol Psychiatry. 2006;59(9):816-20. [ Links ] 5. You SJ, Hu SY, Chen B, Zhang HG. Serotonin transporter and tryptophan hydroxylase gene polymorphisms in Chinese patients with generalized anxiety disorder. Psychiatr Genet. 2005;15(1):7-11. [ Links ] 6. Grant BF, Hasin DS, Stinson FS, Dawson DA, June Ruan W, Goldstein RB, Smith SM, Saha TD, Huang B. Prevalence, correlates, co-morbidity, and comparative disability of DSM-IV generalized anxiety disorder in the USA: results from the national epidemiologic survey on alcohol and related conditions. Psychol Med. 2005;35(12):1747-59. [ Links ] 7. Bruce SE, Yonkers MA, Otto MW, Eisen JL, Weisberg RB, Pagano M, Shea MT, Keller MB. Influence of psychiatric comorbidity on recovery and recurrence in generalized anxiety disorder, social phobia, and panic disorder: a 12-year prospective study. Am J Psychiatry. 2005;162(6):1179-87. [ Links ] 8. Narrow WE, Rae DS, Robins LN, Regier DA. Revised prevalence estimates of mental disorders in the United States: using a clinical significance criterion to reconcile 2 surveys' estimates. Arch Gen Psychiatry. 2002;59(2):115-23. [ Links ] 9. Breslau J, Aguilar-Gaxiola S, Kendler KS, Su M, Williams D, Kessler RC. Specifying race-ethnic differences in risk for psychiatric disorder in a USA national sample. Psychol Med. 2006;36(1):57-68. [ Links ] 10. Mackintosh MA, Gatz M, Wetherell JL, Pedersen NL. A twin study of lifetime Generalized Anxiety Disorder (GAD) in older adults: genetic and environmental influences shared by neuroticism and GAD. Twin Res Hum Genet. 2006;9(1):30-7. [ Links ] 11. Andrade L, Walters EE, Gentil V, Laurenti R. Prevalence of ICD-10 mental disorders in a catchment area in the city of Sao Paulo, Brazil. Soc Psychiatry Psychiatr Epidemiol. 2002;37(7):316-25. [ Links ] 12. Fredrikson M, Furmark T. Amygdaloid regional cerebral blood flow and subjective fear during symptom provocation in anxiety disorders. Ann NY Acad Sci. 2003;985:341-7. [ Links ] 13. Haby MM, Donnelly M, Corry J, Vos T. Cognitive behavioural therapy for depression, panic disorder and generalized anxiety disorder: a meta-regression of factors that may predict outcome. Aust N Z J Psychiatry. 2006;40(1):9-19. [ Links ] 14. Wells A. A cognitive model of generalized anxiety disorder. Behav Modif. 1999;23(4):526-55. [ Links ] 15. Wells A, King P. Metacognitive therapy for generalized anxiety disorder: an open trial. J Behav Ther Exp Psychiatry. 2006;37(3):206-12. [ Links ] 16. Baldwin DS, Polkinghorn C. Evidence-based pharmacotherapy for generalized anxiety disorder. Int J Neuropsychopharm. 2005;8(2):293-302. [ Links ] 17. Frampton JE, Foster RH. Pregabalin: in the treatment of generalised anxiety disorder. CNS Drugs. 2006;20(8):685-93. [ Links ] 18. Allgulander C, Cloninger CR, Przybeck TR, Brandt L. Changes on the