Dr Aaron Beck, an American psychiatrist considered the father of cognitive behavioral therapy, has died aged 100. CBT, which was originally developed to manage depression, aims to help change the way people think to improve how they feel and alter their behavior. Dr Beck"s work is considered hugely influential. He published hundreds of articles and 25 books in his career. A statement from his daughter said he had "transformed the field of mental health" with his life"s work. Dr Beck died peacefully at home on Monday morning, according to a statement from the Beck Institute for Cognitive Behavior Therapy that he and his daughter co-founded. Aaron Beck was born in July 1921 in Providence, Rhode Island to parents who were Russian Jewish immigrants. He studied at Brown University and later graduated with a medical degree from Yale. After his initial training, Dr Beck began to question the basis of typical Freudian psychoanalysis which focused on uncovering conflicts buried within people"s pasts. Instead of focusing on a person"s unconscious, he sought to counter negative thoughts within his patients. People who undergo CBT are encouraged to question their own self-disparaging assumptions and thought processes to change how they see themselves and the world around them. Unlike other talking therapies, it focuses on a patient"s current problems to improve their daily outlook. The technique grew steadily in popularity and became widespread from the 1990s. It is now commonly used to manage anxiety and depression, but it can also be used for other mental health issues such as post-traumatic stress disorders. A statement by Dr Judith Beck, his daughter, said she and her father had "succeeded beyond our expectations" with their institute"s work. "We now honour my father"s legacy as we continue his work and further his mission of helping individuals live healthier, happier and more meaningful lives," her statement said.