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Optimizing the preclinical Alzheimer's cognitive composite with semantic processing: The PACC5
Papp KV, Rentz DM, Orlovsky I, Sperling RA, Mormino EC.. Alzheimer's & dementia (New York, N. Y.), 2017-11-10
Topic: Brain imaging, connectivity and assessment
Introduction Amyloid-related decline in semantic memory was recently shown to be observable in the preclinical period of Alzheimer's disease. Cognitive composites designed to be sensitive to cognitive change in preclinical Alzheimer's disease (e.g., preclinical Alzheimer's cognitive composite [PACC]) and currently used in secondary prevention trials do not currently integrate measures of semantic processing. Our objective was to determine whether a standard semantic measure (i.e., category fluency [CAT] to animals, fruits, and vegetables) adds independent information above and beyond Aβ-related decline captured by the PACC. Methods Clinically normal older adults from the Harvard Aging Brain Study were identified at baseline as Aβ+ (n = 70) or Aβ- (n = 209) using Pittsburgh compound B-positron emission tomography imaging and followed annually with neuropsychological testing for 3.87 ± 1.09 years. The relationships between PACC, CAT, and variations of the PACC including/excluding CAT were examined using linear mixed models controlling for age, sex, and education. We additionally examined decline on CAT by further grouping Aβ+ participants into preclinical stage 1 and stage 2 on the basis of neurodegeneration markers. Results CAT explained unique variance in amyloid-related decline, with Aβ+'s continuing to decline relative to Aβ-'s in CAT even after controlling for overall PACC decline. In addition, removal of CAT from the PACC resulted in a longitudinal Aβ+/- effect size reduction of 20% at 3-year follow-up and 12% at 5-year follow-up. Finally, both stage 1 and stage 2 participants declined on CAT in comparison with stage 0, suggesting CAT declines early within the preclinical trajectory. Conclusion Addition of CAT to the PACC provides unique information about early cognitive decline not currently captured by the episodic memory, executive function, and global cognition components and may therefore improve detection of early Aβ-related cognitive decline.
Key findings
- Results CAT explained unique variance in amyloid-related decline, with Aβ+'s continuing to decline relative to Aβ-'s in CAT even after controlling for overall PACC decline.
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Study details
- Study designlongitudinal study
- Participants70
- Effect sizeor 3.87
- Evidence strengthModerate
How this study scored 71/100
Published in a leading specialty journal, and it is a longitudinal study following the same people over time. Scored zero for randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 41 of the 58 points we could judge it on, which is 71 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Alzheimer's & dementia (New York, N. Y.)) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 7 / 12 | A longitudinal study following the same people over time |
| Strength of evidence | 3 / 5 | Rated “moderate” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 2 / 5 | 2017 — within 10 year(s) of the newest study here |
| Sample size | 1 / 4 | 70 participants |
| Effect reported | 2 / 3 | Effect reported as a number, without an interval or test |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 29264389) |
| Free to read | 2 / 2 | Free to read |
| Points | 41 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 41 of the 58 points we could judge it on is 71 out of 100. |
| Total | 71 / 100 | — |
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APA 7th
Papp, K. V., Rentz, D. M., Orlovsky, I., Sperling, R. A., & Mormino, E. C. (2017). Optimizing the preclinical Alzheimer's cognitive composite with semantic processing: The PACC5. Alzheimer's & dementia (New York, N. Y.). https://doi.org/10.1016/j.trci.2017.10.004
Vancouver
Papp KV, Rentz DM, Orlovsky I, Sperling RA, Mormino EC. Optimizing the preclinical Alzheimer's cognitive composite with semantic processing: The PACC5. Alzheimer's & dementia (New York, N. Y.). 2017. doi:10.1016/j.trci.2017.10.004. PMID: 29264389.
BibTeX
@article{papp2017-29264389,
author = {Papp, K. V. and Rentz, D. M. and Orlovsky, I. and Sperling, R. A. and Mormino, E. C.},
title = {{Optimizing the preclinical Alzheimer's cognitive composite with semantic processing: The PACC5}},
journal = {Alzheimer's \& dementia (New York, N. Y.)},
year = {2017},
doi = {10.1016/j.trci.2017.10.004},
pmid = {29264389},
url = {https://doi.org/10.1016/j.trci.2017.10.004}
}
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