Anxiety is a natural response to stress that helps prepare the body to respond to challenges or perceived threats. However, when feelings of fear, worry, or nervousness become excessive, persistent, or begin to interfere with daily functioning, relationships, work, or overall quality of life, an anxiety disorder may be present.

Depression is a serious mood disorder characterized by persistent sadness, loss of interest in activities, and an inability to experience pleasure. It goes far beyond normal, situational grief and actively interferes with daily functioning, work, and relationships.

Substance use disorder (SUD) is a complex condition in which there is uncontrolled use of a substance despite harmful consequences. People with SUD have an intense focus--sometimes called an addiction--on using a certain substance(s) such as alcohol, tobacco, or other psychoactive substances, to the point where their ability to function in day-to-day life becomes impaired. People keep using the substance even when they know it is causing or will cause problems.

Post-traumatic stress disorder (PTSD) is a mental health condition that's caused by an extremely stressful or terrifying event — either being part of it or witnessing it. Symptoms may include flashbacks, nightmares, severe anxiety and uncontrollable thoughts about the event.

Most people who go through traumatic events may have a hard time adjusting and coping for a short time. But with time and by taking good care of themselves, they usually get better. If the symptoms get worse, last for months or years, and affect their ability to function daily, they may have PTSD.