Final answer:
All patterns mentioned are important in differentiating mental disorders in older individuals, helping to inform appropriate and effective treatment and care.
Step-by-step explanation:
The important pattern to differentiate in older individuals with a mental disorder is: D: All of the above. Understanding the patterns of mental disorders in older individuals is crucial in providing appropriate care and support. Pattern A refers to individuals who have a long history of mental disorder which persists into later life. Recognizing this allows practitioners to understand the chronic nature of the disorder and its impact over time.
Pattern B represents those who experience a mental disorder for the first time in their older age. This can be particularly challenging as it may be confounded with other age-related changes. Lastly, pattern C relates to older individuals who enter later life with a disability, this includes mental disabilities that may exacerbate or complicate mental health issues.