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Primary progressive aphasia and the language network: the 2013 H. Houston Merritt Lecture
Mesulam MM.. Neurology, 2013-07-01
Topic: Brain proteins, microglia and lab models
Objective Review of clinical and biological features of primary progressive aphasia (PPA). Results and conclusions The PPA syndrome arises when language-dominant (usually left) hemisphere becomes the principal target of neurodegeneration. Depending on the distribution of neuronal loss within the language network, agrammatic (PPA-G), logopenic (PPA-L), and semantic (PPA-S) subtypes are identified. The most common underlying neuropathology is frontotemporal degeneration with tauopathy in PPA-G, frontotemporal degeneration with TDP-43 proteinopathy in PPA-S, and Alzheimer pathology in PPA-L. When Alzheimer pathology is detected, the neurofibrillary tangles show lower entorhinal-to-neocortical ratios and greater leftward asymmetry in PPA than in the typical amnestic dementia of Alzheimer disease. The ε4 allele of APOE, a major risk factor for Alzheimer pathology in amnestic dementias, is not a risk factor for Alzheimer pathology in PPA. These observations indicate that Alzheimer disease has biological variants with distinct patterns of lesion distribution and perhaps also molecular background. The selective vulnerability of the language network in PPA is likely to reflect complex interactions between factors that determine the type of histopathology, on one hand, and those that influence the resilience of the language network, on the other. A history of learning disability, including dyslexia, is emerging as one of the potential factors in this second group of determinants. Patient care in PPA should be individualized so that speech therapy can address the specific type of language impairment while pharmacologic therapy is directed to the underlying disease process.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
APA 7th
Mesulam, M. M. (2013). Primary progressive aphasia and the language network: the 2013 H. Houston Merritt Lecture. Neurology. https://doi.org/10.1212/wnl.0b013e31829d87df
Vancouver
Mesulam MM. Primary progressive aphasia and the language network: the 2013 H. Houston Merritt Lecture. Neurology. 2013. doi:10.1212/wnl.0b013e31829d87df. PMID: 23897873.
BibTeX
@article{mesulam2013-23897873,
author = {Mesulam, M. M.},
title = {{Primary progressive aphasia and the language network: the 2013 H. Houston Merritt Lecture}},
journal = {Neurology},
year = {2013},
doi = {10.1212/wnl.0b013e31829d87df},
pmid = {23897873},
url = {https://doi.org/10.1212/wnl.0b013e31829d87df}
}
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Key findings
- Results and conclusions The PPA syndrome arises when language-dominant (usually left) hemisphere becomes the principal target of neurodegeneration.
- These observations indicate that Alzheimer disease has biological variants with distinct patterns of lesion distribution and perhaps also molecular background.
Why it matters
This lecture review describes primary progressive aphasia as arising when the language-dominant hemisphere becomes the principal target of neurodegeneration, with subtypes linked to different underlying pathologies. It notes that Alzheimer disease appears to have biological variants with distinct patterns of lesion distribution and perhaps molecular background.
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Study details
- Evidence strengthLow
How this study scored 45/100
Published in a leading specialty journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Neurology) |
| Journal's citation record | 4 / 4 | Neurology: journal h-index 525 (OpenAlex, 2026-10-29) |
| 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 | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2013 — within 20 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 | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| 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 | 4 / 7 | Cited 85 times (OpenAlex, 2026-10-10) |
| Citations per year | 2 / 5 | 5.7 citations a year over 15 year(s) since 2013 |
| Impact for its field and year | 3 / 6 | Cited 5.3× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 2 / 6 | Cited by 3 other studies in this library |
| Still being cited | 1 / 4 | Cited 8 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Marsel M. Mesulam: h-index 101 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | Northwestern University: institution h-index 1,592 (OpenAlex) |
| Multi-centre collaboration | 0 / 3 | OpenAlex lists 1 institution(s) in 1 country — scores zero (affiliation lists can be incomplete) |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 23897873) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 45 / 100 | — |
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