Background: The phenomenology of delirium is understudied, including how the symptom profile varies across populations. The aim of this study was to explore phenomenology occurring in patients with delirium referred to an old age psychiatry consultation-liaison setting and compare with delirium occurring in palliative care patients.
Methods: Consecutive cases of DSM-IV delirium were assessed with the Delirium Rating scale Revised-98 (DRS-R98) and Cognitive Test for Delirium (CTD).
Results: Eighty patients (mean age 79.3±7.7 years; mean DRS-R98 total score 21.7±4.9 and total CTD score 10.2±6.3) were included. Forty patients (50%) with comorbid dementia were older, had a longer duration of symptoms at referral, and more severe delirium due to greater cognitive impairments. Inattention (100%) was the most prominent cognitive disturbance, while sleep-wake cycle disturbance (98%), altered motor activity (97%), and thought process abnormality (96%) were the most frequent DRS-R98 non-cognitive features. Inattention was associated with severity of other cognitive disturbances on both the DRS-R98 and CTD, but not with DRS-R98 non-cognitive items. The phenomenological profile was similar to palliative care but with more severe delirium due to greater cognitive and non-cognitive disturbance.
Conclusion: Delirium is a complex neuropsychiatric syndrome with generalized cognitive impairment and disproportionate inattention. Sleep-wake cycle and motor-activity disturbances are also common. Comorbid dementia results in a similar phenomenological pattern but with greater cognitive impairment and later referral.