The aim of the present study was to investigate how dispositional resistance to change (RTC) and neuroticism could predict shift work tolerance (SWT) over a period of six months. Electronic questionnaire were completed by 74 shift workers employed in Trondheim municipality in January 2013 (T1) and in June 2013 (T2). The results showed that age, gender, neuroticism, and RTC were related to SWT. Age at T1 predicted better SWT at T2, while male gender predicted worse SWT at T2. RTC at T1 predicted better SWT at T2, while neuroticism at T1 predicted worse SWT at T2. The findings suggest that individual differences, especially neuroticism, can predict SWT over a period of six months.

Syftet med studien var att verifiera sambandet mellan personlighetsdrag, affekt och emotionsreglering. Det undersöktes om hur specifika personlighetsdrag kan predicera användning av emotionsreglering. Utgångspunkten var tidigare forskning som visar korrelationer mellan dessa tre variabler. Undersökningen utfördes online och sammanlagt deltog 47 personer. Extraversion i sig visade sig kunna predicera både användning av Omvärdering och upplevelse av positiv affekt, medan Neuroticism bara verkar kunna predicera negativ affekt. Multipelregressionsanalysen visade att Öppenhet och Vänlighet leder till ökning användning av Omvärdering. Ökningen i Öppenhet var också relaterad till ökning av positiv affekt, samtidigt som Extraversion var relaterad till minskad användning av Supression.  Utöver det hittades positiva korrelationer mellan Supression och negativ affekt samt Omvärdering och positiv affekt, och negativt samband med vice versa.

The relationship between psychological hardiness and individuals' coping with two life events, involuntary job loss and post-parental launching of adolescent children, was investigated in a sample of 146 adults, 83 of which had experienced job loss and 61 of which had experienced the empty nest. Volunteers completed questionnaires which measured hardiness, distress, coping strategies, neuroticism, and extraversion. Multivariate analyses were performed, both with and without covariates, for overall hardiness as well as the hardiness subscales of control, commitment, and challenge. Significant hardiness by life event interactions on escape-avoidance coping were found in both sets of analyses. Main effects for hardiness, however, disappeared when controls for neuroticism and extraversion were utilized. Findings underscore the necessity of employing neuroticism controls in future hardiness research.

Master of Science / Department of Family Studies and Human Services / Jared R. Anderson / Amber V. Vennum / The present study sought to extend the research on cyclical, or on-again/off-again relationships, by examining whether a history of cyclicality moderated the association between neuroticism and relationship satisfaction. A second goal of this study was to examine the direct and indirect effects of neuroticism on relationship satisfaction through communication. The sample consisted of cohabiting cyclical (n = 1,055) and noncyclical (n = 2,527) couples from a larger dataset collected by the RELATE Institute. Results showed that cyclical partners reported higher levels of neuroticism, higher levels of conflict, lower levels of positive communication, and lower levels of relationship satisfaction than noncyclical couples. Direct actor paths from neuroticism to satisfaction were significant for cyclical and noncyclical females and males. Only the direct partner path from female neuroticism to male satisfaction was significant, and was only significant for cyclical couples. All indirect actor and partner paths were significant for cyclical and noncyclical females and males. Further, a history of cyclicality significantly moderated the direct paths from male communication to male and female relationship satisfaction, indicating this relationship is stronger for cyclical couples.

Background: The five-factor model is the most prominent theory in personality science which aspire to understand the thoughts, feelings and behavior of individuals, determined by five relatively stable domains. Neuroticism, defined as a higher threat reactivity and susceptibility to negative affect, is one domain which has proven problematic for well-being, and has estimated societal costs of approximately 2.5 times that of common mental disorder per 1 million inhabitants. Problem: The neural correlates of neuroticism could supply research with a fundamental base of understanding the trait, however, due to scattered founding’s of segregated activity in brain structures relative to neuroticism, meta-analyses argue that increased understanding of global rather than local organization, could be more fruitful for the investigation. Methodology: Since neuroticism is convergent with emotional instability, two structures of interest with regards to global organization are the amygdala, crucial for emotion generation, and the prefrontal cortex (PFC), responsible for emotion interpretation and emotion regulation. Reviewing brain imaging research conducted with emphasis on integrative communication between the amygdala and the PFC in individuals with high trait neuroticism has therefore been the main objective of this thesis. Results/conclusion: According to the investigated research there is compromised structural integrity correlated with neuroticism, while the research on functional communication between the structures explored is not yet sufficiently covered to supply a satisfactory answer. Some of these neurobiological findings are in line with personality science observation in neuroticism, and could hence contribute to the investigation. However, more research is warranted in this field of neuroscience.

The neurocognitive model of antidepressant treatment action states that antidepressants work by producing relatively immediate positive shifts in emotional processing, which translate into clinical improvement with time. Short-term or even acute doses of antidepressants can, for example, increase memory for positive self-referent words or decrease amygdala activation to fearful faces, and these early changes correlate with later clinical improvement. However, there are a number of ways in which the model needs further probing. The aim of this thesis was to test the neurocognitive model by: 1) investigating whether changes in emotional processing occur in an antidepressant with a novel mechanism of action, St John's wort, as the model predicts; and 2) examining whether there is a comparable pattern of neuropsychological changes to citalopram in a population of high neurotic volunteers, whose baseline emotional biases may make them a more ideal group in which to study drug effects. We found that seven days of St John's wort produced similar changes to other antidepressants, for example reducing recognition of disgusted faces and attention to fearful faces while increasing memory for positive words. The drug did not affect other aspects of cognition including working memory and reward learning. These findings support the theory that early psychological changes are a common feature of all antidepressants. On the other hand, four weeks of citalopram treatment produced apparently contradictory effects in high neurotics, increasing memory for positive words but also increasing recognition of negative facial expressions. Neuroimaging data showed that high neurotics had greater response to neutral faces in emotional processing areas compared to low neurotics, which was reduced with citalopram. High neurotics also showed increased resting state connectivity in default mode network areas and between amygdala and cortical areas, which was again reduced with citalopram. We suggest that in this group citalopram corrects general negative emotional processing biases, but also works to decrease a natural aversion to particularly threatening socially-relevant stimuli. Overall this thesis supports the idea that early changes in emotional processing are vital for antidepressant action, but also suggests that in certain groups such as high neurotics, some changes may be more nuanced than previously reported and warrant further scrutiny.

Major Depressive Disorder is a devastating psychiatric illness with a complex genetic and environmental component that affects 10% of the UK population. Previous studies have shown that that individuals with depression show poorer performance on measures of cognitive domains such as memory, attention, language and executive functioning. A major risk factor for depression is a higher level of neuroticism, which has been shown to be associated with depression throughout life. Understanding cognitive performance in depression and neuroticism could lead to a better understanding of the aetiology of depression. The first aim of this thesis focused on assessing phenotypic and genetic differences in cognitive performance between healthy controls and depressed individuals and also between single episode and recurrent depression. A second aim was determining the capability of two decision-tree based methods to detect simulated gene-gene interactions. The third aim was to develop a novel statistical methodology for simultaneously analysing single SNP, additive and interacting genetic components associated with neuroticism using machine leaning. To assess the phenotypic and genetic differences in depression, 7,012 unrelated Generation Scotland participants (of which 1,042 were clinically diagnosed with depression) were analysed. Significant differences in cognitive performance were observed in two domains: processing speed and vocabulary. Individuals with recurrent depression showed lower processing speed scores compared to both controls and individuals with single episode depression. Higher vocabulary scores were observed in depressed individuals compared to controls and in individuals with recurrent depression compared to controls. These significant differences could not be tied to significant single locus associations. Derived polygenic scores using the large CHARGE processing speed GWAS explained up to 1% of variation in processing speed performance among individuals with single episode and recurrent depression. Two greedy non-parametric decision-tree based methods - C5.0 and logic regression - were applied to simulated gene-gene interaction data from Generation Scotland. Several gene-gene interactions were simulated under multiple scenarios (e.g. size, strength of association levels and the presence of a polygenic component) to assess the power and type I error. C5.0 was found to have an increased power with a conservative type I error using simulated data. C5.0 was applied to years of education as a proxy of educational attainment in 6,765 Generation Scotland participants. Multiple interacting loci were detected that were associated with years of education, some most notably located in genes known to be associated with reading and spelling (RCAN3) and neurodevelopmental traits (NPAS3). C5.0 was incorporated in a novel methodology called Machine-learning for Additive and Interaction Combined Analysis (MAICA). MAICA allows for a simultaneous analysis of single locus, polygenic components, and gene-gene interaction risk factors by means of a machine learning implementation. MAICA was applied on neuroticism scores in both Generation Scotland and UK Biobank. The MAICA model in Generation Scotland included 151 single loci and 11 gene-gene interaction sets, and explained ~6.5% of variation in neuroticism scores. Applying the same model to UK Biobank did not lead to a statistically significant prediction of neuroticism scores. The results presented in this thesis showed that individuals with depression performed significantly lower on the processing speed tests but higher on vocabulary test and that 1% of variation in processing speed can be explained by using a large processing speed GWAS. Evidence was provided that C5.0 had increased power and acceptable type I error rates versus logic regression when epistatic models exist - even with a strong underlying polygenic component, and that MAICA is an efficient tool to assess single locus, polygenic and epistatic components simultaneously. MAICA is open-source, and will provide a useful tool for other researchers of complex human traits who are interested in exploring the relative contributions of these different genomic architectures.

One hundred and eighty six adult heterosexual females enrolled in colleges across the United States were sampled to determine the influence of personality and coping variables on female Intimate Partner Aggression (IPA). The research instruments administered included online versions of: the Revised-Conflict Tactics Scale (CTS-2; Straus, Hamby, Boney-McCoy, & Sugarman, 1996), which explored female Intimate Partner Psychological Aggression and Physical Assaultiveness; the International Personality Item Pool (IPIP; Goldberg, 1999), which measured the personality trait of Neuroticism; and the Coping Resources Inventory for Stress-Short Form (CRIS-SF; Matheny, Curlette, Aycock, Pugh, & Taylor, 2007), which assessed the coping resources of Tension Control and Social Support, and provided an overall Coping resource score called Coping Resource Effectiveness (CRE). The role of Neuroticism was highlighted. Neuroticism, but not CRE or specific coping resources, was predictive of Psychological Aggression in females. Neither CRE nor Neuroticism was a significant predictor of Physical Assaultiveness. Implications for reducing psychological aggression in intimate partner relationships were offered.

The aim of the present study was to investigate the connection between anger, personality, stress and gender in 165 students from Växjö University. Previous research has shown that anger is a common negative emotion that occurs in every human being, regardless gender. Anger correlates positively with neuroticism and affects physical and psychological well-being. The questionnaire contained State-Trait Anger Scale (STAXI-2-S), Eysenck´s Personality Questionnaire (EPQ) and the Demand-Control-Support model (DCS). The result showed that there was a significant relation between neuroticism and anger. Anger also correlated positively with support but there were no gender differences in any level of anger.

The purpose of this study was to examine by means of Eysenck Personality Inventory (EPI), the relationship between Neuroticism, and self-rated eating problems. Altogether 105 respondents, mean aged 42,3 years, including 11 men and 94 women, participated by answering an Internet-based questionnaire comprising three different sections. Neuroticism correlated with self-rated eating problems (r=,468, p<0,01). By means of multiple regression analysis it was indicated that both Neuroticism (p<.001) and Body Mass Index (BMI) (p<.001) contributed significantly to the prediction of self-rated eating problems (multiple correlation (ß=.594). The study indicated that the personality only partly explained the variation of eating problems. The result was discussed in terms of significance of biological factors stressing changes in 5-HT levels triggering eating problems.