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Racial Differences and Temporal Trends in Parkinson’s and Alzheimer’s Disease-Related
Ahmmad MR.. medRxiv, 2026-10-24
Topic: Brain imaging, connectivity and assessment
Objective The objectives of this study were to examine racial differences and temporal trends in Alzheimer’s disease (AD)- and Parkinson’s disease (PD)-related mortality among U.S. adults and to assess whether racial mortality patterns and temporal changes differed. Methods We analyzed CDC WONDER Multiple Cause of Death data from 2018-2024, where mortality was defined as deaths with AD or PD recorded as an underlying or contributing cause. Age-standardized mortality rates and adjusted mortality rate ratios (MRRs) were estimated. Joint-point regression evaluated racial differences, annual percentage changes (APCs), and disease-race-year interactions. Sensitivity analyses assessed the robustness of the findings. Results Black had significantly lower PD-related mortality than White (adjusted mortality rate ratios [MRRs]: 0.62-0.69; all p<0.001), whereas AD-related mortality showed no significant racial differences (MRRs: 0.91-1.06). Compared with 2018, mortality increased significantly in 2020 for both diseases among White adults (AD: MRR=1.21; PD: MRR=1.27) and Black adults (AD: MRR=1.27; PD: MRR=1.37), followed by partial declines. PD-related mortality increased significantly among White adults during 2018-2023 (annual percentage change [APC]=3.08%; 95% CI: 1.15%-5.05%), whereas trends among Black adults (APC=3.51%; 95% CI: -2.94% to 10.39%) and AD-related mortality trends in both racial groups were not statistically significant. The disease-race-year interaction was not significant (p=0.942), indicating insufficient evidence that temporal mortality patterns differed jointly. Conclusions Recorded PD-related mortality was lower among Black than White adults, whereas AD-related mortality showed no statistically significant racial difference. These findings support disease-specific mortality surveillance and further investigation of potential differences in diagnostic recognition and death-certificate documentation.
Key findings
- Results Black had significantly lower PD-related mortality than White (adjusted mortality rate ratios [MRRs]: 0.62-0.69; all p<0.001), whereas AD-related mortality showed no significant racial differences (MRRs: 0.91-1.06).
- Compared with 2018, mortality increased significantly in 2020 for both diseases among White adults (AD: MRR=1.21; PD: MRR=1.27) and Black adults (AD: MRR=1.27; PD: MRR=1.37), followed by partial declines.
- PD-related mortality increased significantly among White adults during 2018-2023 (annual percentage change [APC]=3.08%; 95% CI: 1.15%-5.05%), whereas trends among Black adults (APC=3.51%; 95% CI: -2.94% to 10.39%) and AD-related mortality trends in both racial groups were not statistically significant.
- The disease-race-year interaction was not significant (p=0.942), indicating insufficient evidence that temporal mortality patterns differed jointly.
- Conclusions Recorded PD-related mortality was lower among Black than White adults, whereas AD-related mortality showed no statistically significant racial difference.
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Study details
- Effect sizeRR=1.21; RR=1.27; RR=1.37
- Evidence strengthLow
How this study scored 16/100
Preprint — not yet peer-reviewed. It scored 26 on the same rubric, but non-peer-reviewed sources are capped at 16, so it shows as 16. Scored zero for study design, sample size, studied in people and randomised / blinded because the record does not state it. We have no data on 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 16 of the 62 points we could judge it on, which is 26 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 2 / 10 | Tier 4 — not a peer-reviewed journal (medRxiv) |
| Journal's citation record | 0 / 4 | Not a journal article, so the journal's record does not count |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 4 / 10 | Preprint — not yet peer-reviewed. Hosted on a preprint server. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 3 / 3 | Effect reported with a statistic (interval, p-value, ratio or similar) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| 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 | 1 / 2 | Not in PubMed, but has a DOI |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 16 / 62 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 16 of the 62 points we could judge it on is 26 out of 100. |
| Total | 26 / 100 | Capped to 16 because this is not a peer-reviewed article. |
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APA 7th
Ahmmad, M. R. (2026). Racial Differences and Temporal Trends in Parkinson’s and Alzheimer’s Disease-Related. medRxiv. https://doi.org/10.64898/2026.10.22.26366001
Vancouver
Ahmmad MR. Racial Differences and Temporal Trends in Parkinson’s and Alzheimer’s Disease-Related. medRxiv. 2026. doi:10.64898/2026.10.22.26366001.
BibTeX
@article{ahmmad2026-0892d9a4,
author = {Ahmmad, M. R.},
title = {{Racial Differences and Temporal Trends in Parkinson’s and Alzheimer’s Disease-Related}},
journal = {medRxiv},
year = {2026},
doi = {10.64898/2026.10.22.26366001},
url = {https://doi.org/10.64898/2026.10.22.26366001}
}