The Wear-and-Tear Theory proposes that aging is caused by the gradual deterioration of cells and tissues due to accumulated damage from environmental factors, metabolic processes, and free radicals.

The Activity Theory suggests that older adults who continue to engage in meaningful activities, such as work, hobbies, and social interactions, experience greater life satisfaction and well-being.

The Continuity Theory posits that older adults who maintain continuity in their social roles, activities, and relationships experience more successful aging.

The Dual Process Model proposes that individuals oscillate between problem-focused coping, which involves taking steps to address the stressors causing grief, and emotion-focused coping, which aims to manage the emotional distress associated with loss.

The Attachment Theory suggests that individuals with secure attachment relationships tend to experience less complicated grief and are better able to cope with loss.

Anticipatory Grief is the emotional response that occurs in individuals who are aware of an impending loss, such as the death of a loved one due to a terminal illness.

The Purposeful Aging Theory suggests that older adults who have a sense of purpose and meaning in life experience greater well-being and life satisfaction.

Complicated Grief Disorder is a mental health condition characterized by persistent and severe grief symptoms that interfere with an individual's daily functioning.

The Selective Optimization with Compensation Theory proposes that older adults adapt to aging by focusing on their strengths and compensating for their losses through various strategies.

The Socioemotional Selectivity Theory suggests that older adults become more selective in their social interactions, focusing on relationships that provide emotional meaning and support.

Disengagement Theory posits that aging individuals gradually withdraw from social activities and interactions as they prepare for death.

Social Exchange Theory suggests that individuals engage in social interactions based on the perceived costs and benefits of those interactions.

The theory of Meaning-Making in Grief proposes that individuals cope with loss by finding new meaning and purpose in life, often through personal growth and transformation.

Cognitive Decline Theory suggests that older adults experience a decline in cognitive abilities, such as memory, attention, and problem-solving, as a natural part of aging.

The Dual Process Model of Coping with Bereavement suggests that individuals alternate between problem-focused coping, which involves taking steps to address the stressors causing grief, and emotion-focused coping, which aims to manage the emotional distress associated with loss.