This is bipolar disorder. People who shoot and kill innocent people most likely do not have bipolar disorder, Even if they have bipolar disorder, they are NOT shooting others because of it, there is another comorbid issue such as possibly antisocial personality disorder. People who have antisocial personality disorder are the sociopaths and psychopaths of the world. People who have bipolar disorder are decidedly not! Please look at this post as well: Did the Orlando shooter have bipolar d/o? No!

Bipolar disorder (from the Mayo Clinic website) is: Bipolar disorder, formerly called manic depression, causes extreme mood swings that include emotional highs (mania or hypomania) and lows (depression). When you become depressed, you may feel sad or hopeless and lose interest or pleasure in most activities. When your mood shifts in the other direction, you may feel euphoric and full of energy. Mood shifts may occur only a few times a year or as often as several times a week.

For both a manic and a hypomanic episode, during the period of disturbed mood and increased energy, three or more of the following symptoms (four if the mood is only irritable) must be present and represent a noticeable change from your usual behavior:

Criteria for a manic or hypomanic episode

The DSM-5 has specific criteria for the diagnosis of manic and hypomanic episodes:

• A manic episode is a distinct period of abnormally and persistently elevated, expansive or irritable mood that lasts at least one week (or less than a week if hospitalization is necessary). The episode includes persistently increased goal-directed activity or energy.
• A hypomanic episode is a distinct period of abnormally and persistently elevated, expansive or irritable mood that lasts at least four consecutive days.

For both a manic and a hypomanic episode, during the period of disturbed mood and increased energy, three or more of the following symptoms (four if the mood is only irritable) must be present and represent a noticeable change from your usual behavior:

• Inflated self-esteem or grandiosity
• Decreased need for sleep (for example, you feel rested after only three hours of sleep)
• Unusual talkativeness
• Racing thoughts
• Distractibility
• Increased goal-directed activity (either socially, at work or school, or sexually) or agitation
• Doing things that are unusual and that have a high potential for painful consequences — for example, unrestrained buying sprees, sexual indiscretions or foolish business investments

To be considered a manic episode:

• The mood disturbance must be severe enough to cause noticeable difficulty at work, at school or in social activities or relationships; or to require hospitalization to prevent harm to yourself or others; or to trigger a break from reality (psychosis).
• Symptoms are not due to the direct effects of something else, such as alcohol or drug use; a medication; or a medical condition.

To be considered a hypomanic episode:

• The episode is a distinct change in mood and functioning that is not characteristic of you when the symptoms are not present, and enough of a change that other people notice.
• The episode isn’t severe enough to cause significant difficulty at work, at school or in social activities or relationships, and it doesn’t require hospitalization or trigger a break from reality.
• Symptoms are not due to the direct effects of something else, such as alcohol or drug use; a medication; or a medical condition.

Criteria for a major depressive episode

The DSM-5 also lists criteria for diagnosis of a major depressive episode:

• Five or more of the symptoms below over a two-week period that represent a change from previous mood and functioning. At least one of the symptoms is either depressed mood or loss of interest or pleasure.
• Symptoms can be based on your own feelings or on the observations of someone else.

Signs and symptoms include:

• Depressed mood most of the day, nearly every day, such as feeling sad, empty, hopeless or tearful (in children and teens, depressed mood can appear as irritability)
• Markedly reduced interest or feeling no pleasure in all — or almost all — activities most of the day, nearly every day
• Significant weight loss when not dieting, weight gain, or decrease or increase in appetite nearly every day (in children, failure to gain weight as expected can be a sign of depression)
• Either insomnia or sleeping excessively nearly every day
• Either restlessness or slowed behavior that can be observed by others
• Fatigue or loss of energy nearly every day
• Feelings of worthlessness or excessive or inappropriate guilt, such as believing things that are not true, nearly every day
• Decreased ability to think or concentrate, or indecisiveness, nearly every day
• Recurrent thoughts of death or suicide, or suicide planning or attempt

To be considered a major depressive episode:

• Symptoms must be severe enough to cause noticeable difficulty in day-to-day activities, such as work, school, social activities or relationships
• Symptoms are not due to the direct effects of something else, such as alcohol or drug use, a medication or a medical condition
• Symptoms are not caused by grieving, such as after the loss of a loved one