When a person suffers from major depression, it can be very difficult for the individual to maintain normal levels of functioning in school, work, and at home. Major depression is associated with decreased energy levels and fatigue, not "increased energy levels." All of the other answer choices are common symptoms that are indicative of depression.

Mood disorders are a class of disorders that involve gross changes in mood such as major depressive disorder and bipolar disorder. Schizophrenia is a psychotic disorder, OCD and PTSD are also not mood disorders.

Affective disorders are defined by heightened and prolonged emotional states. In the instance of anxiety, which can manifest in many forms, one experiences a consistent state of fear that may or may not have a specific set of triggers. Depression is a prolonged state of sadness and apathy, which often involves a general lack of motivation or pleasant emotions, irritability, difficulty focusing, and, in extreme cases, suicidal thoughts. Bipolar disorder includes this kind of depressive state, yet also a manic one. During the manic state, there is a general feeling of euphoria, an "on top of the world" kind of feeling that may invite impulsive decision-making and an inflated sense of self-importance.

Psychological disorders that are not affective have to do with delusional thinking patterns, personality, attention deficits, addictions, psychosexuality, or developmental problems. While they may share commonalities and even intersect, affective disorders have distinctly to do with prolonged and extreme emotional states, which can be caused by biological or environmental factors.

Dysthymic disorder is a mood disorder that is similar to, but longer-lasting and less disabling, than major depressive disorder. It is diagnosed after at least two years of on-going, mild symptoms of unipolar depression.

Obsessive-compulsive disorder (OCD) is a psychiatric illness characterized by excessive thoughts (obsessions) that lead to repetitive, maladaptive behaviors (compulsions). Common obsessions include a fear of contamination and/or a need to keep things orderly. Common compulsions include obsessive handwashing and counting in certain patterns.

OCD does not arise from a traumatic injury; it results from a combination of psychological and biological factors.

A compulsion is a behavior that one feels driven to perform repeatedly, aiming to reduce stress or prevent the occurrence of something horrible. These compulsive behaviors are quite often linked to obsessive thoughts in cases of Obsessive-Compulsive Disorder (OCD).

The two parts of Obsessive Compulsive Disorder (OCD) are the obsessions and the compulsions. Obsessions are the irrational, intrusive thoughts that distress the person with OCD, and compulsions are the actions that the person takes to try to alleviate the distress of the obsession. In Joanna's case, the fear of someone getting hurt is the obsession and the running up and down the stairs is the compulsion.

Obsessive-compulsive disorder (OCD) is an anxiety disorder characterized by obsessions (intrusive thououghts) and compulsions (intense needs to fulfill specific actions). A common obession is cleanliness, which can lend itself to compulsive hand washing or scrubbing.

Compulsions are repetitive behaviors that are undertaken to reduce anxiety. Some of the most common compulsions in those with OCD (obsessive compulsive disorder) are counting, handwashing, collecting, and organizing at a clinically problematic level. 

Unlike compulsions, which are behaviors that OCD patients feel they must do to prevent disaster or just to reduce their distress, obsessions are unwelcome, unhelpful thoughts that OCD patients actively attempt to ignore or suppress.