Anticipatory grief
The five stages namely, denial, anger, bargaining, depression, and acceptance proposed by Elisabeth Kübler-Ross in her model of grief describe the process by which people undergo after a loss. Anxiety, dread, guilt, helplessness, hopelessness, and feelings of being overwhelmed are also common. However, it is important to note that anticipatory grief is not simply normal grief begun earlier.
Ambiguous loss
The difference between regular grief and grief from an ambiguous loss is the type of loss creates the type of grief experienced. Grief in ambiguous loss can be both beneficial and difficult. Since the grief in an ambiguous loss differs than the linear stages of grief there is no pressure to move on or achieve closure, and this allows for people to remember the lost loved one and move on with relationships and life. There are three specific types of grief that can develop from the type of ambiguous loss. 
Anticipatory grief occurs before bereavement, mourning after death occurs, and upon realizing that death may be imminent for a loved one, anticipatory grief sets in. This type of grief is common among families who have a loved one living with Alzheimer's disease. The grief becomes anticipatory due to the knowledge that the loved one's mental state will only become worse, so the grieving process can start very early.