An anxiety disorder is when an individual experiences excessive amounts of worry beyond what is normally experienced in everyday life. The anxiety typically lasts for 6 or more months before it is considered a disorder. The worrying is very exaggerated and sometimes occurs for no reason at all.
The term mood disorder refers to several disorders including major depression, seasonal affective disorder, mania, and cyclothymia (mild form of bipolar disorder). Individuals with these disorders experience moods that are more severe than what is normal for everyday life. For instance, in major depression, an individual may experience a persistent sad or empty mood and loss of interest in activities that he or she once enjoyed.
A delusional disorder is characterized by having one or more delusions of thinking that are nonbizzare (not unusual). For instance, a person with a delusional disorder might continually think that his or her partner is being unfaithful to him or her, when in fact, there is no truth to that at all.