Complex sentence: Adversity in childhood, such as grief, neglect, mental abuse, and unequal parental treatment of siblings contribute to depression, and physical abuse and sexual abuse significantly increases the likelihood of experiencing depression over the life course.
Split into simpler sentences: Adversity in childhood, such as grief, neglect, mental abuse, and unequal parental treatment of siblings can contribute to depression in adulthood. Childhood physical or sexual abuse in particular significantly increases the likelihood of experiencing depression over the life course.