High rates of delirium and depression are reported in people with dementia so these conditions may co-exist and each needs to be addressed. Dementia and depression are also risk factors for delirium.
Depression, dementia and delirium have some features in common. Depression and delirium, particularly hypoactive delirium, may present with apathy, withdrawal and tearfulness. Delirium occurs suddenly (over a matter of hours or days) and the symptoms tend to fluctuate throughout the day; depression describes a negative change in mood that has persisted for at least two weeks; and the onset of dementia is generally slow and insidious.
Differentiating depression from dementia and delirium requires knowing the characteristic features of each condition (see table below) and establishing the patient’s premorbid cognitive status and mood. This involves obtaining the patient’s history (from the patient or if cognitively impaired from an informant - family or carer or staff) and conducting a depression, cognitive and delirium screen.
Delays in investigating and treating underlying reasons for cognitive impairment, or initiating inappropriate treatment, can have serious consequences for an older person’s health and wellbeing whilst they are in hospital and on discharge.
Delirium must be differentiated from Dementia with Lewy Bodies
It is important to differentiate delirium from Dementia with Lewy Bodies (DLB). These conditions can appear identical, however, haloperidol, which may sometimes be used to manage delirium symptoms, can cause severe movement disturbances (such as spasms or rigidity) and can even be fatal to some patients with DLB. The presence of parkinsonism helps in differentiating DLB from delirium.1
1. Gore, R.L., E.R. Vardy, and J.T. O'Brien, Delirium and dementia with Lewy bodies: distinct diagnoses or part of the same spectrum? J Newurol Neurosurg Psychiatry, 2014. 23.