Anxiety is an emotion characterized by an unpleasant state of inner turmoil, often accompanied by nervous behavior, such as pacing back and forth, somatic complaints and rumination. It is the subjectively unpleasant feelings of dread over anticipated events, such as the feeling of imminent death. Anxiety is not the same as fear, which is a response to a real or perceived immediate threat; whereas anxiety is the expectation of future threat. Anxiety is a feeling of fear, worry, and uneasiness, usually generalized and unfocused as an overreaction to a situation that is only subjectively seen as menacing. It is often accompanied by muscular tension, restlessness, fatigue and problems in concentration. Anxiety can be appropriate, but when experienced regularly the individual may suffer from an anxiety disorder.
People facing anxiety may withdraw from situations which have provoked anxiety in the past. There are different types of anxiety. Existential anxiety can occur when a person faces angst, an existential crisis, or nihilistic feelings. People can also face test anxiety, mathematical anxiety, stage fright or somatic anxiety. Another type of anxiety, stranger anxiety and social anxiety are caused when people are apprehensive around strangers or other people in general. Anxiety can be either a short term 'state' or a long term "trait". Anxiety disorders are a group of mental disorders characterized by feelings of anxiety and fear, whereas trait anxiety is a worry about future events, close to the concept of neuroticism. Anxiety disorders are partly genetic but may also be due to drug use including alcohol and caffeine, as well as withdrawal from certain drugs. They often occur with other mental disorders, particularly major depressive disorder, bipolar disorder, certain personality disorders, and eating disorders. Common treatment options include lifestyle changes, therapy, and medications.
- 1 Descriptions
- 2 Types
- 3 Causes
- 4 See also
- 5 References
- 6 External links
Anxiety is distinguished from fear, which is an appropriate cognitive and emotional response to a perceived threat and is related to the specific behaviors of fight-or-flight responses, defensive behavior or escape. It occurs in situations only perceived as uncontrollable or unavoidable, but not realistically so. David Barlow defines anxiety as "a future-oriented mood state in which one is ready or prepared to attempt to cope with upcoming negative events," and that it is a distinction between future and present dangers which divides anxiety and fear. Another description of anxiety is agony, dread, terror, or even apprehension. In positive psychology, anxiety is described as the mental state that results from a difficult challenge for which the subject has insufficient coping skills.
Fear and anxiety can be differentiated in four domains: (1) duration of emotional experience, (2) temporal focus, (3) specificity of the threat, and (4) motivated direction. Fear is defined as short lived, present focused, geared towards a specific threat, and facilitating escape from threat; while anxiety is defined as long acting, future focused, broadly focused towards a diffuse threat, and promoting excessive caution while approaching a potential threat and interferes with constructive coping.
Anxiety can be experienced with long, drawn out daily symptoms that reduce quality of life, known as chronic (or generalized) anxiety, or it can be experienced in short spurts with sporadic, stressful panic attacks, known as acute anxiety. Symptoms of anxiety can range in number, intensity, and frequency, depending on the person. While almost everyone has experienced anxiety at some point in their lives, most do not develop long-term problems with anxiety.
The behavioral effects of anxiety may include withdrawal from situations which have provoked anxiety in the past. Anxiety can also be experienced in ways which include changes in sleeping patterns, nervous habits, and increased motor tension like foot tapping.
The emotional effects of anxiety may include "feelings of apprehension or dread, trouble concentrating, feeling tense or jumpy, anticipating the worst, irritability, restlessness, watching (and waiting) for signs (and occurrences) of danger, and, feeling like your mind's gone blank" as well as "nightmares/bad dreams, obsessions about sensations, deja vu, a trapped in your mind feeling, and feeling like everything is scary."
The cognitive effects of anxiety may include thoughts about suspected dangers, such as fear of dying. "You may ... fear that the chest pains are a deadly heart attack or that the shooting pains in your head are the result of a tumor or aneurysm. You feel an intense fear when you think of dying, or you may think of it more often than normal, or can't get it out of your mind."
The philosopher Søren Kierkegaard, in The Concept of Anxiety (1844), described anxiety or dread associated with the "dizziness of freedom" and suggested the possibility for positive resolution of anxiety through the self-conscious exercise of responsibility and choosing. In Art and Artist (1932), the psychologist Otto Rank wrote that the psychological trauma of birth was the pre-eminent human symbol of existential anxiety and encompasses the creative person's simultaneous fear of – and desire for – separation, individuation and differentiation.
The theologian Paul Tillich characterized existential anxiety as "the state in which a being is aware of its possible nonbeing" and he listed three categories for the nonbeing and resulting anxiety: ontic (fate and death), moral (guilt and condemnation), and spiritual (emptiness and meaninglessness). According to Tillich, the last of these three types of existential anxiety, i.e. spiritual anxiety, is predominant in modern times while the others were predominant in earlier periods. Tillich argues that this anxiety can be accepted as part of the human condition or it can be resisted but with negative consequences. In its pathological form, spiritual anxiety may tend to "drive the person toward the creation of certitude in systems of meaning which are supported by tradition and authority" even though such "undoubted certitude is not built on the rock of reality".
According to Viktor Frankl, the author of Man's Search for Meaning, when a person is faced with extreme mortal dangers, the most basic of all human wishes is to find a meaning of life to combat the "trauma of nonbeing" as death is near.
Test and performance
According to Yerkes-Dodson law, an optimal level of arousal is necessary to best complete a task such as an exam, performance, or competitive event. However, when the anxiety or level of arousal exceeds that optimum, the result is a decline in performance.
Test anxiety is the uneasiness, apprehension, or nervousness felt by students who have a fear of failing an exam. Students who have test anxiety may experience any of the following: the association of grades with personal worth; fear of embarrassment by a teacher; fear of alienation from parents or friends; time pressures; or feeling a loss of control. Sweating, dizziness, headaches, racing heartbeats, nausea, fidgeting, uncontrollable crying or laughing and drumming on a desk are all common. Because test anxiety hinges on fear of negative evaluation, debate exists as to whether test anxiety is itself a unique anxiety disorder or whether it is a specific type of social phobia. The DSM-IV classifies test anxiety as a type of social phobia.
While the term "test anxiety" refers specifically to students, many workers share the same experience with regard to their career or profession. The fear of failing at a task and being negatively evaluated for failure can have a similarly negative effect on the adult. Management of test anxiety focuses on achieving relaxation and developing mechanisms to manage anxiety.
Humans generally require social acceptance and thus sometimes dread the disapproval of others. Apprehension of being judged by others may cause anxiety in social environments.
Anxiety during social interactions, particularly between strangers, is common among young people. It may persist into adulthood and become social anxiety or social phobia. "Stranger anxiety" in small children is not considered a phobia. In adults, an excessive fear of other people is not a developmentally common stage; it is called social anxiety. According to Cutting, social phobics do not fear the crowd but the fact that they may be judged negatively.
Social anxiety varies in degree and severity. For some people it is characterized by experiencing discomfort or awkwardness during physical social contact (e.g. embracing, shaking hands, etc.), while in other cases it can lead to a fear of interacting with unfamiliar people altogether. Those suffering from this condition may restrict their lifestyles to accommodate the anxiety, minimizing social interaction whenever possible. Social anxiety also forms a core aspect of certain personality disorders, including Avoidant Personality Disorder.
To the extent that a person is fearful of social encounters with unfamiliar others, some people may experience anxiety particularly during interactions with outgroup members, or people who share different group memberships (i.e., by race, ethnicity, class, gender, etc.). Depending on the nature of the antecedent relations, cognitions, and situational factors, intergroup contact may be stressful, and lead to feelings of anxiety. This apprehension or fear of contact with outgroup members is often called interracial or intergroup anxiety.
As is the case in the more generalized forms of social anxiety, intergroup anxiety has behavioral, cognitive, and affective effects. For instance, increases in schematic processing and simplified information processing can occur when anxiety is high. Indeed, such is consistent with related work on attentional bias in implicit memory. Additionally recent research has found that implicit racial evaluations (i.e. automatic prejudiced attitudes) can be amplified during intergroup interaction. Negative experiences have been illustrated in producing not only negative expectations, but also avoidant, or otherwise antagonistic, behavior such as hostility. Furthermore, when compared to anxiety levels and cognitive effort (e.g., impression management and self-presentation) in intragroup contexts, levels and depletion of resources may be exacerbated in the intergroup situation.
Anxiety can be either a short term 'state' or a long term "trait". Trait anxiety reflects a stable tendency to respond with state anxiety in the anticipation of threatening situations. It is closely related to the personality trait of neuroticism. Such anxiety may be conscious or unconscious.
Choice or decision
Anxiety induced by the need to choose between similar options is increasingly being recognized as a problem for individuals and for organizations.
"Today we're all faced with greater choice, more competition and less time to consider our options or seek out the right advice."
In a decision context, unpredictability or uncertainty may trigger emotional responses in anxious individuals that systematically alter decision-making. There are primarily two forms of this anxiety type. The first form refers to a choice in which there are multiple potential outcomes with known or calculable probabilities. The second form refers to the uncertainty and ambiguity related to a decision context in which there are multiple possible outcomes with unknown probabilities.
In some Buddhist meditation literature, this effect is described as something which arises naturally and should be turned toward and mindfully explored in order to gain insight into the nature of emotion, and more profoundly, the nature of self.
Anxiety disorders are a group of mental disorders characterized by feelings of anxiety and fear, where anxiety is a worry about future events and fear is a reaction to current events. These feelings may cause physical symptoms, such as a racing heart and shakiness. There are various forms of anxiety disorders, including generalized anxiety disorder, phobic disorder, and panic disorder. While each has its own characteristics and symptoms, they all include symptoms of anxiety.
Anxiety disorders are partly genetic but may also be due to drug use including alcohol and caffeine, as well as withdrawal from certain drugs. They often occur with other mental disorders, particularly major depressive disorder, bipolar disorder, certain personality disorders, and eating disorders. The term anxiety covers four aspects of experiences that an individual may have: mental apprehension, physical tension, physical symptoms and dissociative anxiety. The emotions present in anxiety disorders range from simple nervousness to bouts of terror. There are other psychiatric and medical problems that may mimic the symptoms of an anxiety disorder, such as hyperthyroidism.
Common treatment options include lifestyle changes, therapy, and medications. Medications are typically recommended only if other measures are not effective. Anxiety disorders occur about twice as often in females as males, and generally begin during childhood. As many as 18% of Americans and 14% of Europeans may be affected by one or more anxiety disorders.
Early life experiences
Anxiety risk factors include family history (e.g. of anxiety) and parenting factors including parental rejection, lack of parental warmth, high hostility, harsh discipline, high maternal negative affect, anxious childrearing, modelling of dysfunctional and drug-abusing behaviour, and child abuse (emotional, physical and sexual).
Research upon adolescents who as infants had been highly apprehensive, vigilant, and fearful finds that their nucleus accumbens is more sensitive than that in other people when deciding to make an action that determined whether they received a reward. This suggests a link between circuits responsible for fear and also reward in anxious people. As researchers note, "a sense of 'responsibility', or self agency, in a context of uncertainty (probabilistic outcomes) drives the neural system underlying appetitive motivation (i.e., nucleus accumbens) more strongly in temperamentally inhibited than noninhibited adolescents". Anxiety is also linked and perpetuated by the person's own pessimistic outcome expectancy and how they cope with feedback negativity. Temperament and attitudes (e.g. pessimism) have been found to be risk factors for anxiety.
People who suffer from anxiety tend to show high activity in response to emotional stimuli in the amygdala.  Although genetics may predispose an individual for an increased risk of an anxiety disorder, it is often the case that external stimuli will trigger its onset.
Social issues - gender
Contextual factors that are thought to contribute to anxiety include gender socialization and learning experiences. In particular, learning mastery (the degree to which people perceive their lives to be under their own control) and instrumentality, which includes such traits as self-confidence, independence, and competitiveness fully mediate the relation between gender and anxiety. That is, though gender differences in anxiety exist, with higher levels of anxiety in women compared to men, gender socialization and learning mastery explain these gender differences. Research has demonstrated the ways in which facial prominence in photographic images differs between men and women. More specifically, in official online photographs of politicians around the world, women's faces are less prominent than men's. Interestingly enough, the difference in these images actually tended to be greater in cultures with greater institutional gender equality.
An evolutionary psychology explanation is that increased anxiety serves the purpose of increased vigilance regarding potential threats in the environment as well as increased tendency to take proactive actions regarding such possible threats. This may cause false positive reactions but an individual suffering from anxiety may also avoid real threats. This may explain why anxious people are less likely to die due to accidents.
Neural circuitry involving the amygdala and hippocampus is thought to underlie anxiety. When people are confronted with unpleasant and potentially harmful stimuli such as foul odors or tastes, PET-scans show increased bloodflow in the amygdala. In these studies, the participants also reported moderate anxiety. This might indicate that anxiety is a protective mechanism designed to prevent the organism from engaging in potentially harmful behaviors.[original research?]
Although single genes have little effect on complex traits and interact heavily both between themselves and with the external factors, research is under-way to unravel possible molecular mechanisms underlying anxiety and comorbid conditions. One candidate gene with polymorphisms that influence anxiety is PLXNA2.
- Scarre, Chris (1995). Chronicle of the Roman Emperors. Thames & Hudson. pp. 168–9. ISBN 978-5-00-050775-9.
- Seligman, M.E.P.; Walker, E.F.; Rosenhan, D.L.. Abnormal psychology (4th ed.). New York: W.W. Norton & Company.[page needed]
- Davison, Gerald C. (2008). Abnormal Psychology. Toronto: Veronica Visentin. p. 154. ISBN 978-0-470-84072-6.
- American Psychiatric Association (2013). Diagnostic and Statistical Manual of Mental Disorders (Fifth ed.). Arlington, VA: American Psychiatric Publishing. p. 189. ISBN 978-0-89042-555-8.
- Bouras, N.; Holt, G. (2007). Psychiatric and Behavioral Disorders in Intellectual and Developmental Disabilities (2nd ed.). Cambridge University Press.[page needed]
- Barker, P. (2003). Psychiatric and Mental Health Nursing: The Craft of Caring. London: Edward Arnold. ISBN 978-0-340-81026-2.[page needed]
- Diagnostic and Statistical Manual of Mental DisordersAmerican Psychiatric Associati. (5th ed. ed.). Arlington: American Psychiatric Publishing. 2013. pp. 189–195. ISBN 978-0890425558.
- Ormel J.; Jeronimus, B.F.; Kotov, M.; Riese, H.; Bos, E.H.; Hankin, B. (2013). "Neuroticism and common mental disorders: Meaning and utility of a complex relationship". Clinical Psychology Review 33 (5): 686–697. doi:10.1016/j.cpr.2013.04.003.
- Öhman, Arne (2000). "Fear and anxiety: Evolutionary, cognitive, and clinical perspectives". In Lewis, Michael; Haviland-Jones, Jeannette M. Handbook of emotions. New York: The Guilford Press. pp. 573–93. ISBN 978-1-57230-529-8.
- Barlow, David H. (2000). "Unraveling the mysteries of anxiety and its disorders from the perspective of emotion theory". American Psychologist 55 (11): 1247–63. doi:10.1037/0003-066X.55.11.1247. PMID 11280938.
- Iacovou, Susan (July 2011). "What is the Difference Between Existential Anxiety and so Called Neurotic Anxiety?: 'The sine qua non of true vitality': An Examination of the Difference Between Existential Anxiety and Neurotic Anxiety". Existential Analysis 22 (2): 356–67. ISSN 1752-5616.
- Csíkszentmihályi, Mihály (1997). Finding Flow.[page needed]
- Sylvers, Patrick; Lilienfeld, Scott O.; Laprairie, Jamie L. (2011). "Differences between trait fear and trait anxiety: Implications for psychopathology". Clinical Psychology Review 31 (1): 122–37. doi:10.1016/j.cpr.2010.08.004. PMID 20817337.
- Rynn MA, Brawman-Mintzer O (2004). "Generalized anxiety disorder: acute and chronic treatment". CNS Spectr 9 (10): 716–23. PMID 15448583.
- Smith, Melinda (2008, June). Anxiety attacks and disorders: Guide to the signs, symptoms, and treatment options. Retrieved March 3, 2009, from Helpguide Web site: http://www.helpguide.org/mental/anxiety_types_symptoms_treatment.htm
- (1987–2008). Anxiety Symptoms, Anxiety Attack Symptoms (Panic Attack Symptoms), Symptoms of Anxiety. Retrieved March 3, 2009, from Anxiety Centre Web site: http://www.anxietycentre.com/anxiety-symptoms.shtml
- (1987–2008). Anxiety symptoms - Fear of dying. Retrieved March 3, 2009, from Anxiety Centre Web site: http://www.anxietycentre.com/anxiety-symptoms/fear-of-dying.shtml
- Tillich, Paul (1952). The Courage To Be. New Haven: Yale University Press. p. 76. ISBN 0-300-08471-4.
- Teigen, Karl Halvor (November 1994). "Yerkes-Dodson: A Law for all Seasons". Theory Psychology 4 (4): 525–47. doi:10.1177/0959354394044004.
- Liebert, Robert M.; Morris, Larry W. (1967). "Cognitive and emotional components of test anxiety: A distinction and some initial data". Psychological Reports 20 (3): 975–978. doi:10.2466/pr0.1918.104.22.1685. PMID 6042522.
- Beidel, D.C.; Turner, S.M. (1988). "Comorbidity of test anxiety and other anxiety disorders in children". Journal of Abnormal Child Psychology 16 (3): 275–287. doi:10.1007/BF00913800. PMID 3403811.
- Rapee, Ronald M.; Heimberg, Richard G. (August 1997). "A cognitive-behavioral model of anxiety in social phobia". Behaviour Research and Therapy 35 (8): 741–56. doi:10.1016/S0005-7967(97)00022-3. PMID 9256517.
- Mathur, S.; Khan, W. (October 2011). "Impact of Hypnotherapy on examination anxiety and scholastic performance among school children" (PDF). Delhi Psychiatry Journal 14 (2): 337–342.
- Hofmann, Stefan G.; Dibartolo, Patricia M. (2010). "Introduction: Toward an Understanding of Social Anxiety Disorder". Social Anxiety. pp. xix–xxvi. doi:10.1016/B978-0-12-375096-9.00028-6. ISBN 978-0-12-375096-9.
- Thomas, Ben; Hardy, Sally; Cutting, Penny, eds. (1997). Mental Health Nursing: Principles and Practice. London: Mosby. ISBN 978-0-7234-2590-8.[page needed]
- Settipani, Cara A.; Kendall, Philip C. (2012). "Social Functioning in Youth with Anxiety Disorders: Association with Anxiety Severity and Outcomes from Cognitive-Behavioral Therapy". Child Psychiatry & Human Development 44 (1): 1–18. doi:10.1007/s10578-012-0307-0. PMID 22581270.
- Stephan, Walter G.; Stephan, Cookie W. (1985). "Intergroup anxiety". Journal of Social Issues 41 (3): 157–175. doi:10.1111/j.1540-4560.1985.tb01134.
- Richeson, Jennifer A.; Trawalter, Sophie (2008). "The threat of appearing prejudiced and race-based attentional biases". Psychological Science 19 (2): 98–102. doi:10.1111/j.1467-9280.2008.02052.x.
- Mathews, Andrew; Mogg, Karin; May, Jon; Eysenck, Michael (1989). "Implicit and explicit memory bias in anxiety". Journal of Abnormal Psychology 98 (3): 236–240. doi:10.1037/0021-843x.98.3.236.
- Richards, Anne; French, Christopher C. (1991). "Effects of encoding and anxiety on implicit and explicit memory performance". Personality and Individual Differences 12 (2): 131–139. doi:10.1016/0191-8869(91)90096-t.
- Amodio, David M.; Hamilton, Holly K. (2012). "Intergroup anxiety effects on implicit racial evaluation and stereotyping". Emotion 12 (6): 1273–1280. doi:10.1037/a0029016.
- Plant, Ashby E.; Devine, Patricia G. (2003). "The antecedents and Implications of Interracial Anxiety". Personality and Social Psychology Bulletin 29: 790–801. doi:10.1177/0146167203029006011.
- Schwarzer, R. (December 1997). "Anxiety". Archived from the original on 2007-09-20. Retrieved 2008-01-12.
- Giddey, M.; Wright, H. Mental Health Nursing: From first principles to professional practice. Stanley Thornes.[page needed]
- Downey, Jonathan (April 27, 2008). "Premium choice anxiety". The Times (London). Retrieved 2010-04-25.
- Is choice anxiety costing british 'blue chip' business?, Capgemini, Aug 16, 2004
- Hartley, Catherine A.; Phelps, Elizabeth A. (2012). "Anxiety and Decision-Making". Biological Psychiatry 72 (2): 113–8. doi:10.1016/j.biopsych.2011.12.027. PMID 22325982.
- Gunaratana, Henepola. "Mindfullness in Plain English - The threefold Guidance".
- Psychiatry, Michael Gelder, Richard Mayou, John Geddes 3rd ed. Oxford; New York: Oxford University Press, c 2005 p. 75
- David Healy, Drugs Explained, Section 5: Management of Anxiety, Elsevier Health Sciences, 2008, pp. 136–137
- Phil Barker (7 October 2003). Psychiatric and mental health nursing: the craft of caring. London: Arnold. ISBN 978-0-340-81026-2. Retrieved 2010-12-17.
- Patel, G; Fancher, TL (Dec 3, 2013). "In the clinic. Generalized anxiety disorder.". Annals of internal medicine 159 (11): ITC6–1, ITC6–2, ITC6–3, ITC6–4, ITC6–5, ITC6–6, ITC6–7, ITC6–8, ITC6–9, ITC6–10, ITC6–11; quiz ITC6–12. doi:10.7326/0003-4819-159-11-201312030-01006. PMID 24297210.
- Kessler RC, Chiu WT, Demler O, Merikangas KR, Walters EE (June 2005). "Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication". Arch. Gen. Psychiatry 62 (6): 617–627. doi:10.1001/archpsyc.62.6.617. PMC 2847357. PMID 15939839.
- Bienvenu, O. Joseph; Ginsburg, Golda S. (2007). "Prevention of anxiety disorders". International Review of Psychiatry 19 (6): 647–54. doi:10.1080/09540260701797837. PMID 18092242.
- O'Connell, Mary Ellen; Boat, Thomas; Warner, Kenneth E., eds. (2009). "Table E-4 Risk Factors for Anxiety". Prevention of Mental Disorders, Substance Abuse, and Problem Behaviors: A Developmental Perspective. National Academies Press. p. 530. ISBN 978-0-309-12674-8.
- Bar-Haim, Yair; Fox, Nathan A.; Benson, Brenda; Guyer, Amanda E.; Williams, Amber; Nelson, Eric E.; Perez-Edgar, Koraly; Pine, Daniel S.; Ernst, Monique (2009). "Neural Correlates of Reward Processing in Adolescents with a History of Inhibited Temperament". Psychological Science 20 (8): 1009–18. doi:10.1111/j.1467-9280.2009.02401.x. PMC 2785902. PMID 19594857.
- Gu, Ruolei; Huang, Yu-Xia; Luo, Yue-Jia (2010). "Anxiety and feedback negativity". Psychophysiology. doi:10.1111/j.1469-8986.2010.00997.x.[non-primary source needed]
- Fricchione, G. (2011). Compassion and Healing in Medicine and Society: On the Nature and Use of Attachment Solutions to Separation Challenges. Johns Hopkins University Press. p. 172. ISBN 9781421402208.
- Harris, J. (1998). How the Brain Talks to Itself: A Clinical Primer of Psychotherapeutic Neuroscience. Haworth. p. 284. ISBN 9780789004086.
- Nolen-Hoeksema, S. (2013). (Ab)normal Psychology (6th edition). McGraw Hill.
- Anticipatory Anxiety Patterns for Male and Female Public Speakers, Ralph Behnke and Chris Sawyer, 1999
- Zalta, Alyson K.; Chambless, Dianne L. (2012). "Understanding Gender Differences in Anxiety: The Mediating Effects of Instrumentality and Mastery". Psychology of Women Quarterly 36 (4): 488–9. doi:10.1177/0361684312450004.
- Andrews, Paul W.; Thomson Jr, J. Anderson (2009). "The bright side of being blue: Depression as an adaptation for analyzing complex problems". Psychological Review 116 (3): 620–54. doi:10.1037/a0016242. PMC 2734449. PMID 19618990.
- Rosen, Jeffrey B.; Schulkin, Jay (1998). "From normal fear to pathological anxiety". Psychological Review 105 (2): 325–50. doi:10.1037/0033-295X.105.2.325. PMID 9577241.
- Zald, David H.; Pardo, Jose V. (1997). "Emotion, olfaction, and the human amygdala: Amygdala activation during aversive olfactory stimulation". Proceedings of the National Academy of Sciences of the United States of America 94 (8): 4119–24. Bibcode:1997PNAS...94.4119Z. doi:10.1073/pnas.94.8.4119. JSTOR 41966. PMC 20578. PMID 9108115.
- Zald, David H.; Hagen, Mathew C.; Pardo, José V. (2002). "Neural Correlates of Tasting Concentrated Quinine and Sugar Solutions". Journal of Neurophysiology 87 (2): 1068–75. PMID 11826070.
- Wray, Naomi R.; James, Michael R.; Mah, Steven P.; Nelson, Matthew; Andrews, Gavin; Sullivan, Patrick F.; Montgomery, Grant W.; Birley, Andrew J.; Braun, Andreas; Martin, NG (2007). "Anxiety and Comorbid Measures Associated with PLXNA2". Archives of General Psychiatry 64 (3): 318–26. doi:10.1001/archpsyc.64.3.318. PMID 17339520.[non-primary source needed]
- "Providing best care for anxiety disorders in general practice". NPS Prescribing Practice Review. NPS MedicineWise. 1 Nov 2009.
Find more about
at Wikipedia's sister projects
|Definitions from Wiktionary|
|Quotations from Wikiquote|