Depression is sometimes mistaken for the typical feeling of sadness that all humans experience from time to time. However, the clear difference between depression and typical sad feelings is that depression is long-term while the feeling of sadness is short-term. Depression is a mental illness that should be taken seriously as this illness can affect the individual emotionally and physically and impair daily life. So, what causes depression? This is the big question that psychologists try to answer through research, but their explanations do not explain how, of those who are faced with one of these factors, only a few are able to avoid developing depression. Everyone thinks and behaves differently, but there are specific personal factors such as negative personality, chronic diseases and substance abuse that cause each individual to respond in a similar and certain way, thus making them prone to developing a disorder depressive. Low self-esteem and negative personality styles can cause depression due to its negative influences on the individual's mind. Chronic diseases trigger depression due to their biological and psychological effects. Ultimately, substance abuse affects an individual's mood, personal life, and health, making them vulnerable to developing depression. Research has shown that there are negative personality traits that can make an individual prone to depression. An individual's negative personality traits can lead them to be perceived more negatively by others, which leads them to feel hurt and rejected (Whitbourne, 2013, para. 9). This is simply because no one likes to be around someone who is constantly negative as it brings negativity into the environment which also lowers the mood of other people. It's...half of the paper......://apt.rcpsych.org/content/8/4/297.fullMulholland, C. (2010, September 22). Alcohol and depression. Netdoctor. Retrieved March 23, 2014, from http://www.netdoctor.co.uk/diseases/depression/alcoholanddepression_000486.htmParker, G., & Manicavasagar, V. (2012, April 13). Personality type and depression. Medical observer. Retrieved March 23, 2014, from http://www.medicalobserver.com.au/news/personality-type-and-depressionThomas, A. (July 20, 2010). Depression and physical illness. Netdoctor. Retrieved March 24, 2014, from http://www.netdoctor.co.uk/diseases/depression/depressionandphysicalillness_000601.htmWhitbourne, S. K. (2013, February 26). Does low self-esteem make you vulnerable to depression? Psychology today. Retrieved March 23, 2014, from http://www.psychologytoday.com/blog/fulfillment-any-age/201302/is-low-self-ESTIMA-making-you-vulnerable-depression