Frontotemporal Dementia (FTD) encompasses a spectrum of clinically and pathologically heterogeneous disorders. This comparison matrix provides a detailed analysis of the four primary FTD subtypes: behavioral variant FTD (bvFTD), semantic variant primary progressive aphasia (svPPA), nonfluent/agrammatic variant PPA (nfvPPA), and logopenic variant primary progressive aphasia (lvPPA).
See Also: Frontotemporal Dementia Overview, TDP-43 Proteinopathy, GRN Gene, MAPT Gene, C9orf72 Gene
| Feature |
bvFTD |
svPPA |
nfvPPA |
lvPPA |
| Core Syndrome |
Behavioral variant |
Language variant |
Language variant |
Language variant |
| Primary Deficit |
Behavior/social cognition |
Word meaning/object knowledge |
Speech production |
Word retrieval/repetition |
| Typical Age of Onset |
45-65 years |
50-70 years |
50-70 years |
60-75 years |
| Disease Duration |
6-12 years |
8-15 years |
6-12 years |
6-10 years |
| Prevalence (of FTD) |
~60% |
~20% |
~15% |
~5% |
Core Diagnostic Features (Rascovsky criteria):
- Disinhibition — Socially inappropriate behavior, loss of manners, impulsive actions
- Apathy — Loss of initiative, decreased interest, reduced emotional expression
- Loss of Empathy — Reduced concern for others, failure to recognize others' needs
- Compulsive Behaviors — Ritualistic, repetitive movements, hoarding, utilization behaviors
Supporting Features:
- Executive dysfunction (planning, organization, mental flexibility)
- Social cognition deficits (recognizing emotions, social cues)
- Motor behaviors (fidgeting, pacing, wandering)
- Dietary changes (binge eating, food preferences)
- Loss of insight (unawareness of changes)
Differential: Can mimic psychiatric disorders (bipolar, depression, OCD), AD, or vascular dementia.
Core Features:
- Anomia — Word-finding difficulty, particularly for low-frequency items
- Single-word Comprehension Deficit — Loss of word meaning, especially for objects
- Surface Dyslexia — Reading words with irregular pronunciation
- Object Agnosia — Inability to recognize objects despite intact vision
- Preserved Speech Fluency — Fluent, grammatically correct speech with empty content
- Preserved Repetition — Normal repetition ability
Behavior Changes (later stage):
- Loss of knowledge about people and objects
- Behavioral features similar to bvFTD in later stages
- Rigid food preferences (sweet foods)
Core Features:
- Agrammatism — Omission of function words, simplified grammar, short phrases
- Hesitant/Slow Speech — Effortful, halting speech production
- Phonological Errors — Sound substitutions, omissions, distortions
- Motor Speech Impairment — Apraxia of speech
- Preserved Word Comprehension — Understanding of single words relatively intact
- Preserved Object Knowledge — Object recognition maintained
Supporting Features:
- Reading/writing impairment (spelling errors)
- Impaired sentence comprehension for complex sentences
- Aprosodia (monotone speech)
- Mildbehavioral changes possible
Core Features:
- Word-finding Pauses — Frequent pauses during speech to retrieve words
- Phonological Errors — Sound-level errors (substitutions, transpositions)
- Impaired Repetition — Particularly for sentences, phrases
- Spared Comprehension — Single-word and sentence comprehension intact
- Spared Speech Fluency — Generally fluent, not halting like nfvPPA
- Preserved Grammar — Grammatical structure preserved
Note: lvPPA is most commonly associated with underlying AD pathology rather than FTLD.
| Subtype |
Key Findings |
Regions Affected |
| bvFTD |
Symmetric or asymmetric frontal/temporal atrophy |
Orbitofrontal, dorsolateral prefrontal, anterior temporal |
| svPPA |
Left anterior temporal lobe atrophy (often asymmetric) |
Left anterior temporal pole, inferior temporal |
| nfvPPA |
Left posterior frontal/inferior parietal atrophy |
Left inferior frontal gyrus, premotor, insular |
| lvPPA |
Left posterior temporal/parietal atrophy |
Left temporoparietal junction, superior temporal |
| Subtype |
Hypometabolism Pattern |
| bvFTD |
Frontal and anterior temporal lobes, anterior cingulate |
| svPPA |
Left anterior temporal and inferior frontal |
| nfvPPA |
Left inferior frontal and premotor |
| lvPPA |
Left posterior temporal and parietal |
- bvFTD: Variable uptake — positive in tauopathy (CBD, PSP), negative in TDP-43 cases
- svPPA: Typically negative (TDP-43 pathology)
- nfvPPA: May show uptake in some cases (tauopathy)
- lvPPA: Often positive (underlying AD pathology in majority of cases)
| Gene |
Protein |
Inheritance |
Subtype Association |
Pathology |
| MAPT |
Tau protein |
Autosomal dominant |
bvFTD, PSP |
FTLD-tau (3R/4R tau) |
| GRN |
Progranulin |
Autosomal dominant |
bvFTD, CBD, PNFA |
FTLD-TDP type A |
| C9orf72 |
Dipeptide repeats |
Autosomal dominant |
bvFTD, ALS-FTD |
FTLD-TDP type B |
| VCP |
Valosin-containing protein |
Autosomal dominant |
bvFTD, IBM |
FTLD-TDP type IV |
| FUS |
Fused in sarcoma |
Autosomal dominant |
bvFTD |
FTLD-FUS |
| CHCHD10 |
Coiled-coil-helix-coiled-coil-helix domain 10 |
Autosomal dominant |
bvFTD, ALS-FTD |
FTLD-TDP |
| Subtype |
Familial % |
Most Common Genes |
| bvFTD |
30-40% |
MAPT, GRN, C9orf72 |
| svPPA |
20-30% |
GRN, MAPT |
| nfvPPA |
30-40% |
GRN, MAPT |
| lvPPA |
~10% |
Usually sporadic (APP/PSEN mutations rare) |
| Clinical Syndrome |
Most Common Pathology |
Other Possible Pathologies |
| bvFTD |
FTLD-TDP (45%), FTLD-tau (40%) |
FTLD-FUS (10%) |
| svPPA |
FTLD-TDP type C (90%) |
FTLD-tau, AD |
| nfvPPA |
FTLD-tau type A (70%) |
FTLD-TDP, AD |
| lvPPA |
AD pathology (70-80%) |
FTLD-TDP, FTLD-tau |
| FTLD-TDP Type |
Clinical Correlates |
| Type A (neuronal intranuclear inclusions) |
bvFTD, nfvPPA, CBD |
| Type B (neuronal cytoplasmic inclusions) |
bvFTD, ALS-FTD |
| Type C (DNR — dystrophic neurites) |
svPPA |
| Type IV (VIP) |
VCP-mutation FTD |
| Approach |
bvFTD |
svPPA |
nfvPPA |
lvPPA |
| SSRIs |
First-line for disinhibition, compulsions |
Limited benefit |
Limited benefit |
Not effective |
| Antipsychotics |
For severe agitation (off-label) |
Not recommended |
Not recommended |
Not recommended |
| Stimulants |
For apathy (low-dose) |
Not used |
Not used |
Not used |
| Speech Therapy |
Limited |
Communication strategies |
Speech production |
Word retrieval strategies |
| Occupational Therapy |
Safety assessment, routines |
Adaptation strategies |
Adaptation strategies |
Adaptation strategies |
| Target |
Approach |
Development Stage |
Relevance |
| Progranulin |
GRN gene therapy, progranulin infusion |
Preclinical/Phase 1 |
GRN carriers (all subtypes) |
| C9orf72 |
ASOs, gene silencing |
Preclinical |
C9orf72 carriers |
| Tau |
Anti-tau antibodies, ASOs |
Phase 2/3 |
MAPT carriers, tauopathy cases |
| TDP-43 |
ASOs targeting TDP-43 |
Preclinical |
TDP-43 pathology cases |
| Intervention |
Application |
| Behavioral strategies |
Structured routines, environmental modifications for bvFTD |
| Communication therapy |
Augmentative/alternative communication for language variants |
| Caregiver education |
Understanding subtype-specific needs, safety planning |
| Swallow assessment |
Progressive dysarthria can affect swallowing safety |
| Feature |
FTD |
AD |
| Onset age |
Earlier (45-65) |
Later (65+) |
| Memory |
Preserved early |
Impaired early |
| Visuospatial |
Preserved early |
Impaired early |
| Language |
Primary in variants |
Secondary, late |
| Behavior |
Early, prominent |
Late, mild |
| MRI |
Frontal/temporal atrophy |
Posterior atrophy (hippocampus) |
| FDG-PET |
Frontal/temporal hypometabolism |
Posterior cingulate, temporoparietal |
| Feature |
svPPA vs nfvPPA |
bvFTD vs svPPA |
| Speech fluency |
svPPA: fluent; nfvPPA: nonfluent |
svPPA: fluent; bvFTD: variable |
| Comprehension |
svPPA: impaired for words; nfvPPA: preserved |
svPPA: impaired for objects |
| Behavior |
nfvPPA: late/rare; svPPA: late |
svPPA: late; bvFTD: early |
| MRI |
Different atrophy patterns |
svPPA: left temporal; bvFTD: frontal |
- Later age of onset
- Slower progression on neuropsychological measures
- Preserved activities of daily living
- Intact socioemotional responsiveness
- Earlier age of onset (particularly <50 years)
- Rapid progression (particularly with motor features)
- GRN mutations (more rapid progression than MAPT)
- Comorbid neuropsychiatric symptoms
| Subtype |
Median Survival from Onset |
| bvFTD |
7-10 years |
| svPPA |
10-15 years |
| nfvPPA |
6-12 years |
| lvPPA |
6-10 years |
- Blood-based biomarkers: Neurofilament light chain (NfL) for progression monitoring
- CSF biomarkers: Total tau, p-tau181, beta-amyloid for differential diagnosis
- Genetic testing: Increasingly important for counseling and clinical trials
| Factor |
Considerations |
| Stage |
Early stage most appropriate for disease-modifying trials |
| Genotype |
GRN, MAPT, C9orf72 carriers may have specific trial eligibility |
| Pathology |
Tau PET status informs eligibility for anti-tau trials |
| Comorbidities |
Exclude significant vascular disease, psychiatric illness |