Neuroticism is a fundamental personality trait in the study of psychology characterized by anxiety, moodiness, worry, envy and jealousy. Individuals who score high on neuroticism are more likely than the average to experience such feelings as anxiety, anger, envy, guilt, and depressed mood. They respond more poorly to environmental stress, and are more likely to interpret ordinary situations as threatening, and minor frustrations as hopelessly difficult. They are often self-conscious and shy, and they may have trouble controlling urges and delaying gratification. Neuroticism is a risk factor for the "internalizing" mental disorders such as phobia, depression, panic disorder, and other anxiety disorders, all of which are traditionally called neuroses.
Emotional stability 
At the opposite end of the spectrum, individuals who score low in neuroticism are more emotionally stable and less reactive to stress. They tend to be calm, even-tempered, and less likely to feel tense or rattled. Although they are low in negative emotion, they are not necessarily high on positive emotion. Being high on positive emotion is an element of the independent trait of extraversion. Neurotic extraverts, for example, would experience high levels of both positive and negative emotional states, a kind of "emotional roller coaster". Individuals who score low on neuroticism (particularly those who are also high on extraversion) generally report more happiness and satisfaction with their lives.
Like other personality traits, neuroticism is typically viewed as a continuous dimension rather than distinct. Neuroticism test scores approximate a normal distribution given a large enough sample of people.
Extent of neuroticism is generally assessed using self-report measures, although peer-reports and third-party observation can also be used. Self-report measures are either lexical or based on statements. Deciding which measure of either type to use in research is determined by an assessment of psychometric properties and the time and space constraints of the study being undertaken.
Lexical measures use individual adjectives that reflect neurotic traits, such as anxiety, envy, jealously, moodiness, and are very space and time efficient for research purposes. Goldberg (1992) developed a 20-word measure as part of his 100-word Big Five markers. Saucier (1994) developed a briefer 8-word measure as part of his 40-word mini-markers. Thompson (2008)  systematically revised these measures to develop the International English Mini-Markers which has superior validity and reliability in populations both within and outside North America. Internal consistency reliability of the International English Mini-Markers for the Neuroticism (emotional stability) measure for native English-speakers is reported as .84, that for non-native English-speakers is .77.
Statement measures tend to comprise more words, and hence consume more research instrument space, than lexical measures. Respondents are asked the extent to which they, for example, Remain calm under pressure, or Have frequent mood swings. While some statement-based measures of neuroticism have similarly acceptable psychometric properties in North American populations to lexical measures, their generally emic development makes them less suited to use in other populations. For instance, statements in colloquial North American English like Seldom feel blue and Am often down in the dumps are sometimes hard for non-native English-speakers to understand.
Neuroticism has also been studied from the perspective of Gray's biopsychological theory of personality, using a scale that measures personality along two dimensions: the Behavioural Inhibition System (BIS) and the Behavioural Activation System (BAS). The BIS is thought to be related to sensitivity to punishment as well as avoidance motivation, while the BAS is thought to be related to sensitivity to reward as well as approach motivation. Neuroticism has been found to be positively correlated with the BIS scale, and negatively correlated with the BAS scale.
Research has found that a wide range of clinical mental disorders are associated with elevated levels of neuroticism compared to levels in the general population. Disorders associated with elevated neuroticism include mood disorders, such as depression and bipolar disorder, anxiety disorders, eating disorders, schizophrenia and schizoaffective disorder, dissociative identity disorder, and hypochondriasis. Mood disorders tend to have a much larger association with neuroticism than these other disorders. Personality disorders as listed in DSM-IV in general tend to be associated with elevated neuroticism. A meta-analysis found that Borderline, Paranoid, Schizotypal, Avoidant, and Dependent Personality disorders were each associated with substantial levels of neuroticism (correlations ranging from .28 to .49). The remaining personality disorders had either modest positive or non-significant (in the case of narcissistic and histrionic) associations with neuroticism.
Neuroticism and depression 
||This section includes inline citations, but they are not properly formatted. (December 2012)|
Neuroticism is a higher-personality dimension related to poor stress coping, irrational thinking, poor impulse control, and worry. It is a strong predictor of psychological problems, especially those related to affective disturbance.
Neuroticism is related to the different levels of depression. Studies have shown that a high level of neuroticism is the first incidence of depression and is the result of future recurrences. Researchers have found that genetic factors that contribute to neuroticism account for close to half of the genetic variance of depression (Roberts and Kendler). In addition, neuroticism is an expression of an underlying genetic vulnerability disorder and is a trait that accounts for anxiety and depression.
Research on psychological outcomes of stress has focused predominantly on major life events, with strong evidence suggesting that the risk of depression is significantly increased following the occurrence of these stressors (Kessler). Researchers have also examined the stresses of daily living. Part of the reason for this shift is due to the evidence that daily hassles mediate the effects of major life events on ones mental and physical well being (Delongis).
Many studies have examined the relationships between neuroticism and stress. Kendler, Kuhn, and Prescott (2004) found that those who score high in neuroticism are more susceptible to long-term depression compared to those who score low in neuroticism. In addition, neuroticism was discovered to prospectively predict changes in depressive symptoms in those who experience a significant change in their lives. Neuroticism controls how one handles a change in their life situation by the inclusion of depression thus suggesting that neuroticism correlates between daily hassles and depression symptoms.
When one does not have a choice in the environment one lives in is the result of the relationship between stress and depression. It is important to consider the effect that neuroticism may have on an individual depending on whether they are exposed to more or less daily hassles when looking into relationship between neuroticism, hassles, and depression symptoms. The existence of daily hassles suggests that it does mediate to some degree the relationship between neuroticism and depressive symptoms. These daily hassles include job loss, marital problems, financial difficulties, and personal conflicts.
Neuroticism appears to be related to physiological differences in the brain. Hans Eysenck theorized that neuroticism is a function of activity in the limbic system, and his research suggests that people who score highly on measures of neuroticism have a more reactive sympathetic nervous system, and are more sensitive to environmental stimulation. Behavioral genetics researchers have found that a significant portion of the variability on measures of neuroticism can be attributed to genetic factors.
A study with positron emission tomography has found that healthy subjects that score high on the NEO PI-R neuroticism dimension tend to have high altanserin binding in the frontolimbic region of the brain — an indication that these subjects tend to have more of the 5-HT2A receptor in that location. Another study has found that healthy subjects with a high neuroticism score tend to have higher DASB binding in the thalamus; DASB is a ligand that binds to the serotonin transporter protein.
Another neuroimaging study using magnetic resonance imaging to measure brain volume found that the brain volume was negatively correlated to NEO PI-R neuroticism when correcting for possible effects of intracranial volume, sex, and age.
Other studies have associated neuroticism with genetic variations, e.g., with 5-HTTLPR — a polymorphism in the serotonin transporter gene. However, not all studies find such an association. A genome-wide association study (GWA study) has associated single-nucleotide polymorphisms in the MDGA2 gene with neuroticism, however the effect sizes were small. Another GWA study gave some evidence that the rs362584 polymorphism in the SNAP25 gene was associated with neuroticism.
A 2008 experiment investigated the neurophysiological responses to uncertainty (which individuals high in neuroticism find aversive) using an event-related potential framework. Participants received positive, negative and uncertain feedback on a task while the feedbackrelated negativity (FRN), an evoked potential that peaks approximately 250 ms after the receipt of feedback information, was measured. For all participants, it was found that a larger FRN occurred after negative feedback than after positive feedback. However, for participants high on neuroticism, uncertain feedback resulted in a larger neural response than did negative feedback.
A 2009 study has found that higher neuroticism is associated with greater loss of brain volume with increasing age.
Mental-noise hypothesis 
Studies have found that the mean reaction times will not differ between individuals high in neuroticism and those low in neuroticism, but that there is considerably more trial-to-trial variability in performance reflected in reaction time standard deviations. In other words, on some trials neurotic individuals are faster than average, and on others they are slower than average. It has been suggested that this variability reflects noise in the individual's information processing systems or instability of basic cognitive operations (such as regulation processes), and further that this noise originates from two sources: mental preoccupations and reactivity processes.
Flehmig et al. (2007) studied mental noise in terms of everyday behaviours using the Cognitive Failures Questionnaire which is a self-report measure of the frequency of slips and lapses of attention. A slip is an error by commission, and a lapse is an error by omission. This scale was correlated with two well-known measures of neuroticism (the BIS/BAS scale and the Eysenck Personality Questionnaire). Results indicated that the CFQ-UA subscale was most strongly correlated with neuroticism (r = .40) and explained the most variance (16%) compared to overall CFQ scores which only explained 7%. The authors interpret these findings as suggesting that mental noise is "highly specific in nature" as it is related most strongly to attention slips triggered endogenously by associative memory. In other words, this may suggest that mental noise is mostly task-irrelevant cognitions such as worries and preoccupations.
Sex differences 
The results of one study has found that on average, women score moderately higher than men on neuroticism. This study examined sex differences in the 'Big Five' personality traits across 55 nations. It found that across the 55 nations studied, the most pronounced difference was in neuroticism. This study found that: In 49 of the 55 nations studied, women scored higher in neuroticism than men. In no country did men report significantly higher neuroticism than women. In Botswana and Indonesia, men scored slightly higher than women. Sex differences in neuroticism within nations ranged from very small to quite large - large in 17 and moderate in 29. Differences were negligible in Bangladesh, Tanzania, Ethiopia, Greece, Japan, Botswana and Indonesia. Large differences were recorded in Israel and Morocco. African and Asian/South Asian world regions tended to have smaller sex differences in personality overall than did western world regions (Europe, and North and South America). Women tended to record similar levels of neuroticism across the regions covered in the study. The men's scores differed widely: men in the Western regions scored lower on neuroticism compared to men in African and Asian world regions. In countries with higher levels of human development, the men recorded significantly lower levels of neuroticism.
||The examples and perspective in this section deal primarily with the United States and do not represent a worldwide view of the subject. (September 2012)|
Neuroticism, along with other personality traits, has been mapped across states in the USA. People in eastern states such as New York, New Jersey, West Virginia, and Mississippi tend to score high on neuroticism, whereas people in many western states, such as Utah, Colorado, South Dakota, Oregon, and Arizona score lower on average. People in states that are higher in neuroticism also tend to have higher rates of heart disease and lower life expectancy.
Evolutionary psychology 
One of the theories regarding evolutionary approaches to depression focuses on neuroticism. A moderate amount of neuroticism may have beneficial effects, such as increased drive and productivity, due to greater sensitivity to negative outcomes. Too much, however, may reduce fitness by producing, for example, recurring depressions. Thus, evolution will select for an optimal amount and most people will have neuroticism near this optimum. However, because neuroticism likely has a normal distribution in the population, a minority will be highly neurotic.
Core self-evaluations 
Neuroticism has been included as one of the four dimensions that comprise core self-evaluations, one's fundamental appraisal of oneself, along with locus of control, self-efficacy, and self-esteem. The concept of core self-evaluations was first examined by Judge, Locke, and Durham (1997), and since found evidence to suggest these have the ability to predict several work outcomes, specifically, job satisfaction and job performance.
See also 
- Thompson, E.R. (October 2008). "Development and Validation of an International English Big-Five Mini-Markers". Personality and Individual Differences 45 (6): 542–548. doi:10.1016/j.paid.2008.06.013.
- G. Matthews and Ian J. Deary (1998). Personality traits. Cambridge, UK: Cambridge University Press.
- Hettema J. M., Neale M. C., Myers J. M., Prescott C. A., Kendler K. S. (2006). "A population-based twin study of the relationship between neuroticism and internalizing disorders". American journal of Psychiatry 163: 857–864.
- Carducci, Bernardo J (2009-02-20). The Psychology of Personality: Viewpoints, Research, and Applications. ISBN 978-1-4051-3635-8.
- Michael W. Passer; Ronald E. Smith (2009). Psychology: the science of mind and behaviour. McGraw-Hill Higher Education. ISBN 978-0-07-711836-5.
- Goldberg, L.R.; Johnson, JA; Eber, HW; et al (2006). "The international personality item pool and the future of public-domain personality measures". Journal of Research in Personality 40 (1): 84–96.
- Goldberg, L.R. (1992). "The development of markers for the Big-Five factor structure". Psychological Assessment 4 (1): 26.
- Saucier, G (1994). "Mini-Markers – a brief version of Goldberg’s unipolar big-five markers". Journal of Personality Assessment 63 (3): 506–516.
- Piedmont, R.L.; Chae, J.H. (1997). "Cross-cultural generalizability of the five-factor model of personality - Development and validation of the NEO PI-R for Koreans". Journal of Cross-Cultural Psychology 28 (2): 131–155.
- Gray, J.A. (1981). A critique of Eysenck's theory of personality, In H.J. Eysenck (Ed.) A model for personality (pp 246–276)
- Gray, J.A. (1982). The neuropsychology of anxiety: An enquiry into the functions of the septo-hippocampal system.
- Boksema, M.A.S, Topsa, M., Westera, A.E., Meijmana, T.F. & Lorist, M.M. (June 2006). "Error-related ERP components and individual differences in punishment and reward sensitivity". Brain Research 1101 (1): 92–101. doi:10.1016/j.brainres.2006.05.004. PMID 16784728.
- Carver, C.S. & White, T.L. (1994). "Behavioral Inhibition, Behavioral Activation, and Affective Responses to Impending Reward and Punishment: The BIS/BAS Scales". Journal of Personality and Social Psychology 67 (2): 319–333. doi:10.1037/0022-3522.214.171.1249.
- Malouff, J.M., Thorsteinsson, E.B., & Schutte N.S. (2005). "The relationship between the five factor model of personality and symptoms of clinical disorders". Journal of Psychopathology and Behavioral Assessment 27 (2): 101–114. doi:10.1007/s10862-005-5384-y.
- Saulsman, L.M. & Page, A.C. (2004). "The five-factor model and personality disorder empirical literature: A meta-analytic review". Clinical Psychology Review 23: 1055–1085. doi:10.1016/j.cpr.2002.09.001. PMID 14729423.
- Hutchinson, Williams (2007). Personality and Individual Differences.
- Hutchinson, James. "Personality and Individual Differences". Elsevier Ltd. Retrieved 1 December 2012.
- Hans Jürgen Eysenck and Michael W. Eysenck (1985). Personality and individual differences: A natural science approach. Perspectives on individual differences. Plenum Press (Springer). ISBN 0-306-41844-4.
- Viken RJ, Rose RJ, Kaprio J, Koskenvuo M. (April 1994). "A developmental genetic analysis of adult personality: extraversion and neuroticism from 18 to 59 years of age". Journal of personality and social psychology 66 (4): 722–30. doi:10.1037/0022-35126.96.36.1992. PMID 8189349.
- Vibe G. Frøkjær, Erik L. Mortensen, Finn Årup Nielsen, Steven Haugbøl, Lars H. Pinborg, Karen H. Adams, Claus Svarer, Steen G. Hasselbalch, Søren Holm, Olaf B. Paulson and Gitte Moos Knudsen (2007). "Frontolimbic Serotonin 2A Receptor Binding in Healthy Subjects Is Associated with Personality Risk Factors for Affective Disorder". Biological Psychiatry 63 (6): 569–76. doi:10.1016/j.biopsych.2007.07.009. PMID 17884017.
- Akihiro Takano, Ryosuke Arakawaa, Mika Hayashia, Hidehiko Takahashia, Hiroshi Itoa & Tetsuya Suhara (September 2007). "Relationship between neuroticism personality trait and serotonin transporter binding". Biological Psychiatry 62 (6): 588–592. doi:10.1016/j.biopsych.2006.11.007. PMID 17336939.
- Brian Knutsona, Reza Momenan, Robert R. Rawlings, Grace W. Fong and Daniel Hommer (November 2001). "Negative association of neuroticism with brain volume ratio in healthy humans". Biological Psychiatry 50 (9): 685–690. doi:10.1016/S0006-3223(01)01220-3. PMID 11704075.
- Klaus-Peter Lesch, D. Bengel, A. Heils, S. Z. Sabol, B. D. Greenberg, S. Petri, J. Benjamin, C. R. Muller, D. H. Hamer, & Dennis L. Murphy (November 1996). "Association of anxiety-related traits with a polymorphism in the serotonin transporter gene regulatory region". Science 274 (5292): 1527–1521. doi:10.1126/science.274.5292.1527. PMID 8929413.
- A. F. Jorm, A. S. Henderson, P. A. Jacomb, H. Christensen, A. E. Korten, B. Rodgers, X. Tan & S. Easteal (September 1998). "An association study of a functional polymorphism of the serotonin transporter gene with personality and psychiatric symptoms". Molecular Psychiatry 3 (5): 449–441. doi:10.1038/sj.mp.4000424. PMID 9774781.
- E. J. van den Oord, P. H. Kuo, A. M. Hartmann, B. T. Webb, H. J. Möller, J. M. Hettema, I. Giegling, J. Bukszár, D. Rujescu (September 2008). "Genomewide Association Analysis Followed by a Replication Study Implicates a Novel Candidate Gene for Neuroticism". Archives of General Psychiatry 65 (9): 1062–1071. doi:10.1001/archpsyc.65.9.1062. PMID 18762592.
- A. Terracciano, S Sanna, M. Uda, B. Deiana, G. Usala, F. Busonero, A. Maschio, M. Scally, N. Patriciu, W.-M. Chen, M. A. Distel, E. P. Slagboom, D. I. Boomsma, S. Villafuerte, E. S. liwerska, M. Burmeister, N. Amin, A. C. J. W. Janssens, C. M. van Duijn, D. Schlessinger, G. R. Abecasis and P. T. Costa Jr (October 2008). "Genome-wide association scan for five major dimensions of personality". Molecular Psychiatry 15 (6): 647–56. doi:10.1038/mp.2008.113. PMC 2874623. PMID 18957941.
- Hirsh J. B., Inzlicht M. (2008). "The devil you know: Neuroticism predicts neural response to uncertainty". Psychological Science 19: 962–967.
- Jackson, J.; Balota, D.; Head, D. (2009). "Exploring the relationship between personality and regional brain volume in healthy aging". Neurobiol Aging 32 (12): 2162–2171. doi:10.1016/j.neurobiolaging.2009.12.009. ISSN 0197-4580. PMC 2891197. PMID 20036035. Lay summary.
- Robinson, M.D & Tamir, M. (2006). "Neuroticism as mental noise: a relation between neuroticism and reaction time standard deviations". Journal of Personality and Social Psychology 89 (1): 107–114. doi:10.1037/0022-35188.8.131.52. PMID 16060749.
- Flehmig, H.C., Steinborn, M., Langner, R., & Westhoff, K. (2007). "Neuroticism and the mental noise hypothesis: Relationships to lapses of attention and slips of action in everyday life". Psychology Science 49 (4): 343–360.
- David P. Schmitt; Realo, A; Voracek, M., & Allik, J. (2008). "Why can't a man be more like a woman? Sex differences in big five personality traits across 55 cultures.". Journal of Personality and Social Psychology 94 (1): 168–182. doi:10.1037/0022-35184.108.40.206. PMID 18179326.
- Stephanie Simon (2008-09-23). "The United States of Mind. Researchers Identify Regional Personality Traits Across America". WSJ.com. Original research article: Peter J. Rentfrow, Samuel D. Gosling and Jeff Potter (2008). "A Theory of the Emergence, Persistence, and Expression of Geographic Variation in Psychological Characteristics". Perspectives on Psychological Science 3 (5): 339–369. doi:10.1111/j.1745-6924.2008.00084.x.
- Allen, N.; Badcock, P. (2006). "Darwinian models of depression: A review of evolutionary accounts of mood and mood disorders". Progress in Neuro-Psychopharmacology and Biological Psychiatry 30 (5): 815–826. doi:10.1016/j.pnpbp.2006.01.007. PMID 16647176.
- Judge T. A., Locke E. A., Durham C. C. (1997). "The dispositional causes of job satisfaction: A core evaluations approach". Research in Organizational Behavior 19: 151–188.
- Bono, J. E., & Judge, T. A. (2003). Core self-evaluations: A review of the trait and its role in job satisfaction and job performance. European Journal of Personality, 17(Suppl 1), S5-S18. doi:10.1002/per.48
- Dormann C., Fay D., Zapf D., Frese M. (2006). "A state-trait analysis of job satisfaction: On the effect of core self-evaluations". Applied Psychology: An International Review 55 (1): 27–51.
- Judge T. A., Locke E. A., Durham C. C., Kluger A. N. (1998). "Dispositional effects on job and life satisfaction: The role of core evaluations". Journal of Applied Psychology 83 (1): 17–34.
- Judge T. A., Bono J. E. (2001). "Relationship of core self-evaluations traits—self-esteem, generalized self-efficacy, locus of control, and emotional stability—with job satisfaction and job performance: A meta-analysis". Journal of Applied Psychology 86 (1): 80–92.