Stage Models of Normal Grief
A number of theoretically derived stage models of normal grief have been proposed.[14,15,16,17] Most models hypothesize a normal grief process differentiated from various types of complicated grief. Some models have organized the variety of grief-related symptoms into phases or stages, suggesting that grief is a process marked by a series of phases, with each phase consisting of predominant characteristics. One well-known stage model, focusing on the responses of terminally ill patients to awareness of their own deaths, identified the stages of denial, anger, bargaining, depression, and acceptance. Although widely used, this model has received little empirical support.
A more recent stage model of normal grief  organizes psychological responses into four stages: numbness-disbelief, separation distress, depression-mourning, and recovery. Although presented as a stage model, this model explains "it is important to emphasize that the idea that grief unfolds inexorably in regular phases is an oversimplification of the highly complex personal waxing and waning of the emotional process." Bereavement researchers have found empirical support for this four-stage model, although other researchers have questioned these findings.[19,20]
Patterns of Complicated Grief
Since the time of Sigmund Freud, many authors have proposed various patterns of pathologic or complicated grief.[1,2] Some proposed patterns come from extensive clinical observation  supported by various theories (e.g., psychodynamic defense mechanisms and personality traits associated with patterns of attachment).
These patterns are described in comparison to normal grief and highlight variations from the normal pattern. They include descriptive labels such as the following:
- Inhibited or absent grief: A pattern in which persons show little evidence of the expected separation distress, seeking, yearning, or other characteristics of normal grief.
- Delayed grief: A pattern in which symptoms of distress, seeking, yearning, etc., occur at a much later time than is typical.
- Chronic grief: A pattern emphasizing prolonged duration of grief symptoms.
- Distorted grief: A pattern characterized by extremely intense or atypical symptoms.
Empirical reviews have not found evidence of inhibited, absent, or delayed grief and instead emphasize the possibility that these patterns are better explained as forms of human resilience and strength. Evidence supports the existence of a minimal grief reaction—a pattern in which persons experience no, or only a few, signs of overt distress or disruption in functioning. This minimal reaction is thought to occur in 15% to 50% of persons during the first year or two after a loss.
Empirical support also exists for chronic grief, a pattern of responding in which persons experience symptoms of common grief but do so for a much longer time than the typical year or two. Chronic grief is thought to occur in about 15% of bereaved persons. It may look very much like major depression, generalized anxiety, and possibly post-traumatic stress.