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  1. Inott, Theresa RN, MSN

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How can I differentiate between delirium, dementia, and depression in the older adults I care for in the medical/surgical unit? - -C.H., MASS.


Theresa Inott, RN, MSN, replies: The clinical features of delirium, dementia, and depression may overlap in older adults, and all involve memory impairment. But sorting them out is essential because your interventions depend on an accurate assessment.


Delirium is a reversible state of acute confusion, abrupt in onset. The patient's thinking is disorganized, and he can't answer specific mental status questions in a logical way. Delirium usually has an underlying, treatable cause, such as an infection (for example, a urinary tract or respiratory infection), adverse drug reaction, dehydration, hypoxia, metabolic disturbance, or nutritional deficiency.


Dementia, which usually is progressive and irreversible, is characterized by memory loss that interferes with the patient's ability to function independently. When you assess his mental status, he may try diligently to find the appropriate response, but miss the correct answer. Someone with early dementia may be aware of his disordered thinking and become quite distressed by his inability to respond correctly.


As dementia progresses, he loses other cognitive abilities, resulting in aphasia, apraxia, and agnosia (inability to recognize familiar persons or objects). Alzheimer's disease is the most common form of dementia in older adults; other causes of dementia include head trauma, thyroid disorders, and vitamin B12 deficiency.


Depression in older adults often is confused with dementia. On mental status testing, the patient often answers, "I don't know" or "I can't remember." He may give up attempting to answer or seem unconcerned, which can give the impression that he's disoriented. However, when gently encouraged, he may provide detailed and coherent information. His thought process is intact, but slowed. In contrast, someone with dementia or delirium communicates poorly because of his disorganized or distorted thought processes.


Some signs and symptoms of depression are the same in older adults as in younger patients, such as sad mood, lack of pleasure in things that once were pleasurable, difficulty concentrating, and changes in eating, sleeping, and elimination patterns. To help determine if a patient is depressed, administer a validated depression screening test, such as the Geriatric Depression Scale, assess for thoughts of suicide and suicide risk, and take appropriate precautions.


A thorough patient history and physical assessment will help you differentiate these disorders in your patients.




Husain M, et al. Age-related characteristics of depression: A preliminary STAR*D report. American Journal of Geriatric Psychiatry. 13(10):852-860, October 2005.


Milisen K, et al. Cognitive assessment and differentiating the 3 Ds (dementia, depression, delirium). Nursing Clinics of North America. 41(1):1-22, March 2006.