The revised Addenbrooke's Cognitive Examination can facilitate differentiation of dementia with Lewy bodies from Alzheimer's disease

Development of the Brazilian version of the Mini-Addenbrooke Cognitive Examination (M-ACE BR) to screen for cognitive impairment in older adults

BACKGROUND

 Age is the most important risk factor for develop dementia, and the recommendation is that older adults are cognitively tested to detect impairment in the initial stage for adequate treatment. The demand for the care of these older adults is great, drawing attention to the need for rapid tests, with good accuracy and simple application to identify cognitive impairment.

OBJECTIVE

 To develop and validate the Brazilian Mini-Addenbrooke Cognitive Examination (M-ACE BR) as a short screening test for cognitive impairment in older adults.

METHODS

 The M-ACE BR was developed using the Mokken scaling analysis in 352 participants (cognitively unimpaired [CU] = 232, cognitive impairment no dementia [CIND] = 82; and dementia = 38) and validated in an independent sample of 117 participants (CU = 25; CIND = 88; and dementia = 4).

RESULTS

 The Mokken scaling analysis derived 9 items (spatial orientation, anterograde memory, retrograde memory, delayed recall, recognition [name and address], letter verbal fluency, repetition of 4 words, naming of 10 items, and comprehension) with a maximum score of 51 points and an average duration time of 7 minutes. The cut-off score ≤ 43/51 for CIND had a sensitivity of 59.09% and a specificity of 80%. For a screening test in which sensitivity is prioritized for further investigation, we suggest using a cutoff of ≤ 47 (sensitivity 85.23% and specificity 24%), maintaining a good positive predictive value (79.8%).

CONCLUSION

 The M-ACE BR is a brief and adequate instrument to detect cognitive impairment in older Brazilian adults. However, screening for CIND and for different educational levels should be further explored.

Differential levels of plasma biomarkers of neurodegeneration in Lewy body dementia, Alzheimer's disease, frontotemporal dementia and progressive supranuclear palsy

OBJECTIVES

This longitudinal study compared emerging plasma biomarkers for neurodegenerative disease between controls, patients with Alzheimer's disease (AD), Lewy body dementia (LBD), frontotemporal dementia (FTD) and progressive supranuclear palsy (PSP).

METHODS

Plasma phosphorylated tau at threonine-181 (p-tau181), amyloid beta (Αβ)42, Aβ40, neurofilament light (NfL) and glial fibrillar acidic protein (GFAP) were measured using highly sensitive single molecule immunoassays (Simoa) in a multicentre cohort of 300 participants (controls=73, amyloid positive mild cognitive impairment (MCI+) and AD dementia=63, LBD=117, FTD=28, PSP=19). LBD participants had known positron emission tomography (PET)-Aβ status.

RESULTS

P-tau181 was elevated in MCI+AD compared with all other groups. Aβ42/40 was lower in MCI+AD compared with controls and FTD. NfL was elevated in all dementias compared with controls while GFAP was elevated in MCI+AD and LBD. Plasma biomarkers could classify between MCI+AD and controls, FTD and PSP with high accuracy but showed limited ability in differentiating MCI+AD from LBD. No differences were detected in the levels of plasma biomarkers when comparing PET-Aβ positive and negative LBD. P-tau181, NfL and GFAP were associated with baseline and longitudinal cognitive decline in a disease specific pattern.

CONCLUSION

This large study shows the role of plasma biomarkers in differentiating patients with different dementias, and at monitoring longitudinal change. We confirm that p-tau181 is elevated in MCI+AD, versus controls, FTD and PSP, but is less accurate in the classification between MCI+AD and LBD or detecting amyloid brain pathology in LBD. NfL was elevated in all dementia groups, while GFAP was elevated in MCI+AD and LBD.

An adaptive measure of visuospatial impairment in Dementia with Lewy Bodies

Background

Dementia with Lewy bodies (DLB) is a common cause of dementia with poor prognosis and high hospitalization rates. DLB is frequently misdiagnosed, with clinical features that overlap significantly with other diseases including Parkinson's disease (PD). Clinical instruments that discriminate and track the progression of cognitive impairment in DLB are needed.

Objectives

The current study was designed to assess the utility of a mental rotation (MR) task for assessing visuospatial impairments in early DLB.

Methods

Accuracy of 22 DLB patients, 22 PD patients and 22 age‐matched healthy controls in the MR task were compared at comparing shapes with 0°, 45° and 90° rotations.

Results

Healthy controls and PD patients performed at similar levels while the DLB group were significantly impaired. Further, impairment in the visuospatial and executive function measures correlated with MR poor outcomes.

Conclusion

These findings support the MR task as an objective measure of visuospatial impairment with the ability to adjust difficulty to suit impairments in a DLB population. This would be a useful tool within clinical trials.