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Abstract
Objective To determine whether patients with Lewy body dementia (LBD) with likely Alzheimer disease (AD)–type copathology are more impaired on confrontation naming than those without likely AD-type copathology.
Methods We selected 57 patients with LBD (dementia with Lewy bodies [DLB], n = 38; Parkinson disease dementia [PDD], n = 19) with available AD CSF biomarkers and neuropsychological data. CSF β-amyloid1-42 (Aβ42), phosphorylated-tau (p-tau), and total-tau (t-tau) concentrations were measured. We used an autopsy-validated CSF cut point (t-tau:Aβ42 ratio > 0.3, n = 43), or autopsy data when available (n = 14), to categorize patients as having LBD with (LBD + AD, n = 26) and without (LBD − AD, n = 31) likely AD-type copathology. Analysis of covariance tested between-group comparisons across biologically defined groups (LBD + AD, LBD − AD) and clinical phenotypes (DLB, PDD) on confrontation naming (30-item Boston Naming Test [BNT]), executive abilities (letter fluency [LF], reverse digit span [RDS]), and global cognition (Mini-Mental State Examination [MMSE]), with adjustment for age at dementia onset, time from dementia onset to test date, and time from CSF to test date. Spearman correlation related cognitive performance to CSF analytes.
Results Patients with LBD + AD performed worse on BNT than patients with LBD − AD (F = 4.80, p = 0.03); both groups performed similarly on LF, RDS, and MMSE (all p > 0.1). Clinically defined PDD and DLB groups did not differ in performance on any of these measures (all p > 0.05). A correlation across all patients showed that BNT score was negatively associated with CSF t-tau (ρ = −0.28, p < 0.05) and p-tau (ρ = −0.26, p = 0.05) but not Aβ42 (p > 0.1).
Conclusion Markers of AD-type copathology are implicated in impaired language performance in LBD. Biologically based classification of LBD may be advantageous over clinically defined syndromes to elucidate clinical heterogeneity.
Glossary
- Aβ=
- β-amyloid1-42;
- AChEI=
- acetylcholinesterase inhibitor;
- AD=
- Alzheimer disease;
- ANCOVA=
- analysis of covariance;
- BNT=
- Boston Naming Test;
- DLB=
- dementia with Lewy bodies;
- LBD=
- Lewy body dementia;
- LF=
- letter fluency;
- MMSE=
- Mini-Mental State Examination;
- p-tau=
- phosphorylated tau;
- PD=
- Parkinson disease;
- PDD=
- PD dementia;
- RDS=
- reverse digit span;
- t-tau=
- total tau
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
- Received July 9, 2020.
- Accepted in final form January 6, 2021.
- © 2021 American Academy of Neurology
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