123I-MIBG myocardial scintigraphy and neurocirculatory abnormalities in patients with dementia with Lewy bodies and Alzheimer's disease

Abstract

BackgroundAlthough adoption of new clinical criteria for dementia with Lewy bodies (DLB) leads to an increase in the proportion of patients diagnosed with probable DLB, the sensitivity of clinical diagnostic criteria of DLB is low, and there are no generally accepted clinical or imaging biomarkers to distinguish DLB from other types of dementia. In this study, we investigated whether neurocirculatory abnormalities and cardiac sympathetic denervation differed in controls and patients with subjective memory impairment (SMI), mild cognitive impairment (MCI), Alzheimer's disease (AD), and DLB. We also assessed whether spontaneous features of Parkinsonism might be related to the neurocirculatory abnormalities and cardiac sympathetic denervation found in DLB. MethodsTwenty-two consecutive patients with probable DLB were enrolled in this study; 25 age-matched controls, 14 SMI, 24 MCI, and 37 AD patients were also evaluated. Metaiodobenzylguanidine (MIBG) uptake was assessed using the ratio of the heart to the upper mediastinum (H/M ratio), and orthostatic vital signs and ambulatory 24-hour blood pressure monitoring values were recorded. ResultsThe mean H/M ratio was significantly lower and the proportion of orthostatic hypotension was higher in patients with DLB than in controls, SMI, MCI and AD patients. In patients with DLB, spontaneous Parkinsonism was not related to the degree of cardiac sympathetic denervation nor did it influence neurocirculatory abnormalities. ConclusionOur results suggest that MIBG scintigraphy and autonomic function tests may be useful for distinguishing between DLB and AD in clinical practice. Myocardial postganglionic sympathetic denervation and autonomic dysfunctions are present in patients with DLB regardless of spontaneous Parkinsonism.