Freud believed that schizophrenia was caused by regression to an early mental state due to an inability to cope with unacceptable urges. Later psychodynamic theorists, like Sullivan, argued that schizophrenia results from a gradual withdrawal from relationships that begins with an anxious and hostile parent-child relationship in early childhood. This withdrawal continues in a cycle until early adulthood, when new social demands cause such extreme anxiety that the person disengages completely from relationships and reality.