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Differentiation of dementia with Lewy bodies from Alzheimer's disease using a dopaminergic presynaptic ligand

Abstract

Background: Dementia with Lewy bodies (DLB) is one of the main differential diagnoses of Alzheimer's disease (AD). Key pathological features of patients with DLB are not only the presence of cerebral cortical neuronal loss, with Lewy bodies in surviving neurones, but also loss of nigrostriatal dopaminergic neurones, similar to that of Parkinson's disease (PD). In DLB there is 40–70% loss of striatal dopamine.

Objective: To determine if detection of this dopaminergic degeneration can help to distinguish DLB from AD during life.

Methods: The integrity of the nigrostriatal metabolism in 27 patients with DLB, 17 with AD, 19 drug naive patients with PD, and 16 controls was assessed using a dopaminergic presynaptic ligand, 123I-labelled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)nortropane (FP-CIT), and single photon emission tomography (SPET). A SPET scan was carried out with a single slice, brain dedicated tomograph (SME 810) 3.5 hours after intravenous injection of 185 MBq FP-CIT. With occipital cortex used as a radioactivity uptake reference, ratios for the caudate nucleus and the anterior and posterior putamen of both hemispheres were calculated. All scans were also rated by a simple visual method.

Results: Both DLB and PD patients had significantly lower uptake of radioactivity than patients with AD (p<0.001) and controls (p<0.001) in the caudate nucleus and the anterior and posterior putamen.

Conclusion: FP-CIT SPET provides a means of distinguishing DLB from AD during life.

  • FP-CIT single photon emission tomography
  • dementia with Lewy bodies
  • Alzheimer's disease
  • DLB, dementia with Lewy bodies
  • AD, Alzheimer's disease
  • PD, Parkinson's disease
  • SPET, single photon emission tomography
  • FP-CIT, 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)nortropane
  • MMSE, mini mental state examination
  • CAMCOG, Cambridge cognitive function examination
  • CDR, clinical dementia rating
  • BEHAVE-AD, behavioural pathology in Alzheimer's disease
  • UPDRS, unified Parkinson's disease rating scale
  • H&Y stage, Hoehn and Yahr stage
  • CAPE, Clifton assessment procedure for the elderly

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Footnotes

  • Competing interests: DCC received some financial support from Nycomed Amersham plc, now called Amersham Healthcare. IGMcK has received consultancy fees and research funds from Nycomed Amersham plc. ZW has received research funds from Nycomed Amersham plc.

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