Deciphering the 4 D's: cognitive decline, delirium, depression and dementia – a review

PURPOSE: The purpose of this paper is to assist advanced practice nurses to recognize, identify, and diagnose cognitive change in older adults. BACKGROUND/RATIONALE: Optimal cognitive function is important for continued independence, and yet changes in cognition are frequently unrecognized among older adults. Cognitive change in older adults can be observed due to age-related cognitive decline, the development of acute confusion (delirium), depression, dementia and/or a combination of these. When the aetiological source for alterations in cognitive function is delirium or depression, the potential for reversibility mandates that the reason for the cognitive change be identified with steps taken to remedy the situation. Also, early recognition of dementia is an important factor in obtaining timely and appropriate care. These conditions can exist concurrently and may fluctuate making deciphering the reason for the cognitive change problematic. CONCLUSIONS: It is essential to understand how the 4 'D's' are expressed and to recognize the potential contributing factors to an observable change in cognitive function for diagnosis and treatment. Recommendations for obtaining a person's history are included.