Does the Etiology, Phenomenology and Motor Subtype of Delirium Differ When It Occurs in Patients With An Underlying Dementia?: A Multi-Site, International Study

OBJECTIVES

To compare the etiology, phenomenology and motor subtype of delirium in patients with and without an underlying dementia.

METHODS

A combined dataset (n = 992) was collated from two databases of older adults (>65 years) from liaison psychiatry and palliative care populations in Ireland and India. Phenomenology and severity of delirium were analysed using the Delirium Symptom Rating Scale Revised (DRS-R98) and contributory etiologies for the delirium groups were ascertained using the Delirium Etiology Checklist (DEC). Delirium motor subtype was documented using the abbreviated version of the Delirium Motor Subtype Scale (DMSS4).

RESULTS

Delirium superimposed on dementia (DSD) showed greater impairment in short term memory, long term memory and visuospatial ability than the delirium group but showed significantly less perceptual disturbance, temporal onset and fluctuation. Systemic infection, cerebrovascular and other Central nervous system etiology were associated with DSD while metabolic disturbance, organ insufficiency and intracranial neoplasm were associated with the delirium only group.

CONCLUSION

The etiology and phenomenology of delirium differs when it occurs in the patient with an underlying dementia. We discuss the implications in terms of identification and management of this complex condition.

Comparison of novel tools with traditional cognitive tests in detecting delirium in elderly medical patients

BACKGROUND

Efficient detection of delirium and comorbid delirium-dementia is a key diagnostic challenge. Development of new, efficient delirium-focused methods of cognitive assessment is a key challenge for improved detection of neurocognitive disorders in everyday clinical practice.

AIM

To compare the accuracy of two novel bedside tests of attention, vigilance and visuospatial function with conventional bedside cognitive tests in identifying delirium in older hospitalized patients.

METHODS

180 consecutive elderly medical inpatients (mean age 79.6 ± 7.2; 51% female) referred to a psychiatry for later life consultation-liaison service with delirium, dementia, comorbid delirium-dementia and cognitively intact controls. Participants were assessed cross-sectionally with conventional bedside cognitive tests [WORLD, Months Backward test (MBT), Spatial span, Vigilance A and B, Clock Drawing test and Interlocking Pentagons test] and two novel cognitive tests [Lighthouse test, Letter and Shape Drawing test (LSD)-4].

RESULTS

Neurocognitive diagnoses were delirium (n = 44), dementia (n = 30), comorbid delirium-dementia (n = 60) and no neurocognitive disorder (n = 46). All conventional tests had sensitivity of > 70% for delirium, with best overall accuracy for the Vigilance-B (78.3%), Vigilance-A (77.8%) and MBT (76.7%) tests. The sustained attention component of the Lighthouse test was the most distinguishing of delirium (sensitivity 84.6%; overall accuracy 75.6%). The LSD-4 had sensitivity of 74.0% and overall accuracy 74.4% for delirium identification. Combining tests allowed for enhanced sensitivity (> 90%) and overall accuracy (≥ 75%) with the highest overall accuracy for the combination of MBT-Vigilance A and the combined Vigilance A and B tests (both 78.3%). When analyses were repeated for those with dementia, there were similar findings with the MBT-Vigilance A the most accurate overall combination (80.0%). Combining the Lighthouse-SA with the LSD-4, a fail in either test had sensitivity for delirium of 91.4 with overall accuracy of 74.4%.

CONCLUSION

Bedside tests of attention, vigilance and visuospatial ability can help to distinguish neurocognitive disorders, including delirium, from other presentations. The Lighthouse test and the LSD-4 are novel tests with high accuracy for detecting delirium.