In the study of psychology, neuroticism has been considered a fundamental personality trait. For example, in the Big Five approach to personality trait theory, individuals with high scores for neuroticism are more likely than average to be moody and to experience such feelings as anxiety, worry, fear, anger, frustration, envy, jealousy, guilt, depressed mood, and loneliness. Such people are thought to respond worse to stressors and are more likely to interpret ordinary situations, such as minor frustrations, as appearing hopelessly difficult. The responses can include maladaptive behaviors, such as dissociation, procrastination, substance use, etc., which aids in relieving the negative emotions and generating positive ones.

People with high scores on the neuroticism index are thought to be at risk of developing common mental disorders (mood disorders, anxiety disorders, and substance use disorders have been studied), and the sorts of symptoms traditionally referred to as "neuroses".