9. Delirium and Dementia: Similar but Not Synonymous
People often conflate delirium and dementia, but although they share some similarities—like cognitive impairment—they are distinct conditions. Dementia is usually a gradual decline, whereas delirium is rapid in onset. But that’s just the tip of the iceberg; these conditions can sometimes co-exist, making diagnosis and treatment that much more complex.
Delirium may be superimposed on dementia, complicating both diagnosis and treatment. This is a particularly precarious situation because the abrupt and fluctuating symptoms of delirium are laid atop the steady cognitive decline characteristic of dementia. This dual diagnosis often creates a highly challenging clinical picture.
What’s more, having dementia can make one more susceptible to delirium. The cognitive reserve already compromised by dementia gets further depleted, making the brain more vulnerable to the imbalances that trigger delirium. It’s like a one-two punch that leaves both the individual and their caregivers reeling.(9)
