Prospective cohort study of 44 Geriatric Medicine patients in 4 groups: (1) delirium, no history of dementia; (2) DSD; (3) acute illness without delirium or dementia; and (4) AD, no delirium. We measured CBF using transcranial Doppler to assess flow velocity (FV) and pulsatility index in the middle cerebral artery (MCA).
DSD has lower FV than either AD or delirium alone, or acute illness (28.2 ± 4.7 vs AD: 41.3 ±15.7; P = .040; vs delirium 37.7 ± 8.2; P =.009; vs acute illness 43.0 ± 8.3; P <.001). A mean MCA FV cut-off of 32.25 cm/s diagnoses DSD with a sensitivity of 0.875 and specificity of 0.788, area under the curve 0.884; P = .001. Resolution of delirium improves FV (P = .005). FV correlates with delirium severity (delirium index R = −0.39; P = .009) and dementia (Mini-Mental State Examination, R = 0.33; P = .029, and Informant Questionnaire on Cognitive Decline in the Elderly, R = −0.41; P = .005).
Transcranial Doppler is a potential diagnostic and monitoring test for DSD. Correlation with clinical indicators of delirium suggests pathophysiological significance.