Detecting deficits of sustained visual attention in delirium

Inattention is a core clinical feature of delirium and yet the particular aspects of attentional impairment associated with this feature are poorly understood. Objective methods for assessing inattention are also lacking. A new set of computerised tests of attentional deficits designed for use in patients with delirium have been developed. Test performances in patients with delirium, dementia and cognitively normal controls are compared.

Eight novel tasks measuring sustained visual attention were administered to 20 older patients with delirium using the Edinburgh Delirium Test Box, a purpose built, computerised neuropsychological testing device. Comparison groups of 18 patients with Alzheimer's dementia and 20 cognitively normal patients of similar age were also assessed. Delirium was diagnosed using the Confusion Assessment Method. General cognitive impairment was measured using the Mini-Mental State Examination.

Patients with delirium had significantly lower scores than both comparison groups on all sustained attention tasks (p values from 0.003 to <0.001). Performance of the dementia patients generally did not differ from the cognitively normal group. Receiver operating characteristic analyses indicated that all tasks showed good or excellent accuracy for discriminating between delirium and dementia (AUC values 0.80-0.94), and between delirium and cognitively normal (AUC values 0.89-0.99) patients.

Patients with delirium showed marked deficits in sustained visual attention, as measured by objective neuropsychological testing. These attentional deficits were mainly mild or absent in patients with dementia and in cognitively normal controls. Objective testing of sustained visual attention has promising utility in detecting delirium, and in discriminating delirium from dementia.