Kertesz

ORIGINAL CONTRIBUTION

What Is Semantic Dementia?
A Cohort Study of Diagnostic Features and Clinical Boundaries
Andrew Kertesz, MD; Sarah Jesso, BA; Michal Harciarek, PhD; Mervin Blair, MA; Paul McMonagle, MD

Objectives: To describe a large, clinically defined co- tions were frequent in SD (54.1%) but phonological er-
hort of patients with semantic dementia (SD) that high- rors were absent, in contrast to progressive nonfluent
lights important, sometimes overlooked features and to aphasia with the opposite pattern. All but 3 patients with
compare it with similar entities. probable SD questioned the meaning of words. Patients
with SD had significantly lower naming and comprehen-
Design: Cohort study. sion scores, and their fluency was between progressive
nonfluent aphasia and Alzheimer disease or behavioral
Setting: A cognitive neurology clinic. frontotemporal dementia. Behavior was abnormal in
94.6% of patients with probable SD.
Patients: A population of 48 patients clinically diag-
nosed with SD was contrasted with 52 patients with pro- Conclusions: Semantic dementia is distinguishable from
gressive nonfluent aphasia, 42 patients with a behav-
other presentations of frontotemporal dementia and Alz-
ioral variety of frontotemporal dementia, and 105 patients
heimer disease, not only by fluent speech and impaired
with Alzheimer disease on speech output characteris-
tics, comprehension, naming, and repetition subtests of comprehension without loss of episodic memory, syn-
the Western Aphasia Battery, the Frontal Behavioral In- tax, and phonology but also by empty, garrulous speech
ventory, and other cognitive tests. Neuroimaging was vi- with thematic perseverations, semantic paraphasias, and
sually analyzed, and 6 patients with SD had autopsy. poor category fluency. Questioning the meaning of words
(eg, “What is steak?”) is an important diagnostic clue not
Results: Of 37 patients with probable SD, 48.6% had se- seen in other groups, and behavior change is prevalent.
mantic jargon; 21.6%, excessive garrulous output; and
75.7%, some pragmatic disturbance. Semantic substitu- Arch Neurol. 2010;67(4):483-489

S
EMANTIC DEMENTIA (SD) Snowden et al1 and has been adopted by
designates a progressive cog- others,9 including the consensus criteria
nitive and language deficit, of Neary et al,13 as a variety of frontotem-
primarily involving compre- poral dementia (FTD). The incidence of
hension of words and related SD is estimated by one clinic to be 25% in
semantic processing.1 These patients lose their patients with FTD.12
the meaning of words, usually nouns, but Semantic dementia has been equated
retain fluency, phonology, and syntax. with fluent progressive aphasia.9,14 Flu-
Author Affiliations:
Department of Clinical Pick2 described similar patients as hav- ent aphasia, however, is common in Alz-
Neurological Sciences, ing “pure word deafness” in association heimer disease (AD)15 and, at the onset,
University of Western Ontario with left temporal atrophy. Transcortical all patients with progressive aphasia are
(Dr Kertesz), and Cognitive sensory aphasia was used for similar cases.3 fluent, even those who become nonflu-
Neurology and Alzheimer Semantic aphasia was a term used by Head4 ent later.16,17 The fluency-nonfluency dis-
Research Centre, St Joseph’s in war-injured patients for a 2-way distinction is often arbitrary and rarely quan-
Hospital, London, Ontario, turbance of comprehension and naming. titated. Primary progressive aphasia is
Canada (Dr Kertesz and The condition was called gogi (meaning) subdivided variably and sometimes in-
Ms Jesso); University of aphasia in Japan.5 Some patients were con- cludes SD. Here we used the term pro-
Gdansk, Gdansk, Poland
´ ´
sidered to have loss of semantic memory6 gressive nonfluent aphasia (PNFA) for a
(Dr Harciarek); Concordia
University, Montreal, Canada and others a language impairment.7,8 Se- comparison group. Semantic deficits, con-
(Mr Blair); and the Department mantic dementia has been further elabo- sidered basic to SD, also appear in AD.18
of Neurology, Royal Victoria rated as the degradation of a single cen- Because of these overlapping features from
Hospital, Belfast, Northern tral network of conceptual knowledge.9-12 different clinical and biological entities, the
Ireland (Dr McMonagle). The definition of SD originates from diagnostic boundaries remain uncertain.

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Table 1. Clinical Features of Semantic Dementia a

Sex/Age
at Onset, y/ Duration of Memory Questioning Visual Face Surface Speech Neurological Autopsy
1st Syndrome Illness, y b for Names Words Agnosia Agnosia Pragmatics Art c Dyslexia Output Image Findings
F/60/SD 4 1 1 1 1 1 ... 1 Empty LTA FTLD-U
F/56/bvFTD 4 1 1 1 1 1 ... 1 Stereotypy RTA LF FTLD-U
M/61/bvFTD 6 1 ... ... ... 1 ... 1 Semantic jargon LTA FTLD-U
M/46/SD 1 1 1 1 ... 1 1 1 Empty LTA FTLD-U
M/38/bvFTD 2 1 ... ... 1 ... ... ... Semantic jargon, perseverative LTA FTLD-U
F/64/bvFTD 1 1 1 ... ... ... ... ... Perseverative FTA DLDH
F/51/bvFTD 7 1 1 1 0 1 ... 1 Semantic jargon Diffuse ...
F/68/bvFTD 3 ... 1 1 1 1 ... ... Semantic jargon R LTA ...
F/56/SD 3 ... 1 ... ... 1 1 1 Semantic jargon LTA ...
F/65/SD 2 1 1 1 ... ... 0 Tangential L RTA ...
M/51/SD 6 1 1 1 1 ... ... 1 Empty LTA ...
M/63/SD 1 1 1 1 ... 1 ... ... Semantic jargon, perseverative Diffuse ...
F/46/SD 4 1 1 1 1 ... ... 1 Semantic jargon L RTA ...
F/48/SD 3 ... ... 1 1 1 ... ... Garrulous, semantic jargon LFTA ...
F/55/SD 1 1 1 ... ... 1 ... 1 Semantic jargon LTA ...
M/48/SD 2 1 1 0 1 1 ... 1 Dysarthric L RTFA ...
F/47/bvFTD 4 1 1 1 1 1 ... Garrulous LTPA ...
M/66/bvFTD 6 ... 1 ... ... 1 ... ... Garrulous, stereotypy FTA ...
F/57/SD 3 1 1 0 ... 1 Empty LTPA ...
F/72/bvFTD 5 ... 1 1 0 1 ... ... Garrulous, abusive LTA ...
M/67/SD 3 1 1 ... ... 1 ... ... Semantic jargon LTA ...
M/60/bvFTD 1 0 1 1 0 1 ... ... Semantic jargon FTA L R ...
M/72/SD 5 1 1 ... ... 1 ... ... Stereotypy FTA ...
M/58/bvFTD 5 ... 1 ... ... 1 ... ... Semantic jargon LTPA ...
F/64/bvFTD 5 1 1 ... ... ... ... 1 Semantic jargon R LFTA ...
M/69/SD 5 1 1 ... ... 1 1 1 Semantic jargon L RTA ...
F/62/bvFTD 6 1 1 1 1 1 ... ... Garrulous, perseverative L RTA ...
M/59/SD 4 1 1 ... ... 1 ... 1 Semantic jargon L RTA ...
F/63/SD 4 1 1 ... ... 1 ... 1 Perseverative RFTA ...
F/54/SD 6 1 1 ... 1 1 ... 1 Garrulous LTA ...
F/58/SD 3 ... 1 ... 1 ... 1 ... Semantic jargon LTA ...
M/57/SD 5 1 1 ... ... 1 1 ... Garrulous L RTA ...
M/64/SD 3 1 1 ... 0 1 1 1 Perseverative L RTA ...
F/66/SD 4 1 1 ... ... ... 1 ... Normal, fluent L RTA ...
M/59/bvFTD 10 1 1 ... ... 1 1 ... Semantic jargon L RTFA ...
M/52/bvFTD 9 ... 1 0 1 1 1 1 Stereotypy, semantic jargon LTFA ...
F/41/bvFTD 2 1 1 1 1 1 ... ... Perseverative, garrulous RTFA ...
Total d 28 34 13 15 28 9 18

Abbreviations: A, atrophy; ellipses, not tested for; bvFTD, behavioral frontotemporal dementia; DLDH, dementia lacking distinctive histology; F, frontal;
FTLD-U, frontotemporal lobar degeneration with ubiquitin-positive inclusions; L, left; P, parietal; R, right; SD, semantic dementia; T, temporal.
a 0 indicates that a symptom does not exist; 1, symptom exists.
b Years from onset of illness to first clinical visit.
c Indicates an obsession with painting or jigsaw puzzles.
d For men, n = 17; women, n=20; mean (SD) age, 58 (8.4) years; a total of 21 patients had SD; 16, bvFTD; the mean (SD) duration of illness was 4 (2.1) years.

Some features of SD such as distinctive speech output 361 patients with FTD or Pick complex. Patients with SD had
characteristics, impaired pragmatics (the study of the give- progressive loss of naming and comprehension, with preserved
and-take and efficiency of communication), “What is . . . ” syntax, phonology, fluency, and relatively preserved episodic
questioning of meaning, and behavioral abnormality are memory. They were followed up at yearly intervals,20 but only
relatively unexplored. We aimed to study SD in a cog- the results of the first examination were used for the statistical
analyses in this study. Thirty-seven patients were considered to
nitive neurology clinic population of patients in an at-
have probable SD (Table 1). This group had prominent com-
tempt to delineate the syndrome from the behavioral pre- prehension and word-finding difficulty, either from the begin-
sentation of patients with FTD (bvFTD), PNFA, and AD. ning of the illness or by the first time they were seen. Patients
In addition to comparing neurocognitive features with with possible SD (n=11) were cases with atypical features and
related conditions, we characterized the pragmatics of were not included in the statistical analysis. One patient had epi-
speech and quantitated language, including fluency and sodic memory loss and 2 had confused close relatives as strang-
the behavioral abnormality. In view of a recent sugges- ers (the Capgras delusion), which raised the suspicion of pos-
tion associating a specific pathology with SD,19 the study sible AD.21 One patient had significant vascular disease and
of clinical boundaries of SD is even more relevant. We another panic attacks. Five possible cases had predominant be-
report autopsy confirmation in 6 of 48 patients. havioral disturbance and only incipient SD by the first clinic visit,
and 1 had mixed nonfluent and SD features.
Behavioral FTD was diagnosed clinically when a patient pre-
METHODS sented with mainly behavioral or personality disturbance, ful-
filling Neary and colleagues’ criteria,13 and no significant lan-
The target population was 48 patients with SD who were diag- guage impairment was evident on the first examination. Patients
nosed clinically using the Neary et al criteria13 from a cohort of with PNFA had an initial deficit of language output and pres-

484

Table 2. Demographics, Cognitive Screening, and Behavior

Mean (SD)

Variable SD bvFTD AD PFNA P Value
Age (n=37) (n = 31) (n = 105) (n = 52)
57.92 (8.38) a,b 58.48 (8.43) c,d 67.67 (8.62) b,d 64.37 (7.30) a,c .002 a
.000 b
.010 c
.000 d
Years ill (n=37) (n = 42) (n = 105) (n = 52)
4.0 (2.13) a,b,c 2.96 (2.92) c 2.59 (1.67) b 2.65 (1.43) a .009 a
.001 b
.019 c
MMSE (n=29) (n = 34) (n = 35) (n = 32)
(max: 30) 21.48 (6.63) 25.03 (4.43) a,b 19.71 (7.26) b 19.44 (7.71) a .004 a
.006 b
FBI (n=32) (n = 38) (n = 28) (n = 37)
(max: 72, cutoff: 27.47 (15.35) a,b,c 36.84 (11.52) c,d,e 14.61 (10.40) b,e 16.86 (11.21) a,d .003 a
30) .000 b
.010 c
.000 d
.000 e
DRS (n=25) (n = 26) (n = 95) (n = 45)
(max: 144) 101.40 (23.59) a 120.19 (25.75) a,b,c 105.33 (21.26) c 99.09 (30.16) b .034 a
.003 b
.034 c
Clock drawing test (n=14) (n = 19) (n = 31) (n = 10)
(max: 10) 6.29 (2.86) 8.21 (1.87) 6.37 (3.03) 6.15 (3.38) No significant differences
Animal Fluency (n=32) (n = 18) (n = 105) (n = 52)
(normal above 12) 5.66 (3.80) a,b 11.67 (5.87) b,c 9.22 (4.44) a 7.83 (5.10) c .001 a
.000 b
.015 c

Abbreviations: AD, Alzheimer disease; bvFTD, behavioral frontotemporal dementia; DRS, Dementia Rating Scale; FBI, Frontal Behavioral Inventory;
max, maximum; MMSE, Mini-Mental State Examination; PFNA, progressive nonfluent aphasia; SD, semantic dementia.
a-eScores are significantly different in pairwise comparison (Tukey, post hoc) in each row (eg, in the MMSE row, only 2 comparisons are significant, bvFTD with
PNFA and bvFTD with AD).

ervation of comprehension, memory, and visuospatial ability. Patients with SD and bvFTD were younger than those with
Patients with additional memory and comprehension prob- AD and PNFA (Table 2). The sex distribution was 16 women
lems in their history were excluded as having possible PNFA. to 21 men in the SD group, 13 to 29 in bvFTD group, 32 to 22 in
Alzheimer disease was diagnosed when the primary deficit was the PNFA group, and 41 to 64 in the AD group. 2 analysis showed
(episodic) memory impairment and the patients fulfilled the that the PNFA group had significantly more women than the
National Institute of Neurological and Communicative Disor- bvFTD ( 2 =7.7; P=.006) and AD groups ( 2 =5.9; P=.02). The
ders and Stroke/Alzheimer’s Disease and Related Disorders As- time from onset of illness to first examination was longer in pa-
sociation (NINCDS/ADRDA) criteria. tients with SD. The institutional review board of University of
The patients were grouped on the basis of a clinical inter- Western Ontario approved the study of human subjects.
view and neurological examination, independently of the neu-
ropsychological assessment to avoid circularity. The Mini-
Mental State Examination, Dementia Rating Scale, Clock RESULTS
Drawing Test, and Category fluency (animals per minute) tests
measured cognition. Language testing was performed with the COGNITION
Western Aphasia Battery (WAB). The aphasia quotient repre-
sents a total score and overall measure of the severity of lan-
guage impairment; major subtests are fluency, speech con- Table 2 shows the results of comparison of all groups on
tent, comprehension of nouns and sentences, repetition, naming, cognitive and behavioral tests. Analyses of variance and
reading, and writing. A subset of patients with SD was also ex- Tukey post hoc tests showed significantly better perfor-
amined for the supplementary reading and writing of irregu- mance by the bvFTD group when compared with the
lar words. The clinical description of conversational speech char- PNFA and AD groups on the Mini-Mental State Exami-
acteristics was additional to formal language assessment with nation and the Dementia Rating Scale. Patients with SD
the WAB. Behavior and personality change was rated on the were also better, but not significantly. The animal flu-
Frontal Behavioral Inventory, with higher score indicating greater
behavioral change.22 The side and lobar locations of promi-
ency task revealed that patients with SD performed sig-
nent atrophy or hypometabolism on magnetic resonance imaging nificantly worse than those with AD and bvFTD. Not only
or computed tomography and hexylmethylpropylene amineox- was visuospatial function preserved in our SD cohort, but
ine–single-photon emission computed tomography was re- we also observed a heightened, at times obsessive, incli-
viewed by A. K. and P. M. (Table 1) but the radiological fea- nation to paint and complete jigsaw puzzles in 9 pa-
tures were not used in patient grouping. tients with SD (Table 1). Visual object agnosia (13 of 37

485

100
SD bvFTD PPA AD

90

80

70

60
Score, %

50

40

30

20

10

0
Aphasia Quotient Fluency Auditory Word Recognition Sequential Command Naming Objects Repetition

Figure. Language function on the subtests of the Western Aphasia Battery comparing semantic dementia (SD) with behavioral frontotemporal dementia (bvFTD),
primary progressive aphasia (PPA) (progressive nonfluent aphasia), and Alzheimer disease (AD). Raw scores are converted to percentages of the maximum score,
usually achieved by controls. *P .05; significant difference from semantic dementia.

patients) and prosopagnosia (15 of 37 patients) was ob- the SD group (n = 31) with the bvFTD (n = 17), PNFA
vious enough to be observed by the caregivers or the ex- (n=52), and AD groups (n=105). Analysis of variance
aminer (Table 1). showed a significant difference between the groups as mea-
sured by the aphasia quotient; the AD and bvFTD groups
SPEECH OUTPUT had significantly less language deficit than the SD group.
The AD group was significantly more fluent than the SD
Speech output in patients with SD was fluent (WAB flu- group, and patients with PNFA were significantly less flu-
ency rating of 6 or higher) in all cases. Eighteen of the 37 ent than the bvFTD and AD groups but not significantly
patients had semantic jargon, defined as speech that is mean- different from the SD group. Auditory (single noun) word
ingless and irrelevant but grammatically and phonologi- recognition and sequential commands (sentence com-
cally correct, consisting of real words. Empty speech is simi- prehension) were significantly lower in SD than AD pa-
lar, but has some coherence and conversational relevance tients. In naming objects, the SD group was signifi-
(n=4). Nine patients had significant thematic or semantic cantly worse than all others.
perseveration (stereotypy), and 8 patients were garrulous, Using the WAB classification criteria, our patients with
with excessive output that incorporated some of the above SD were classified as follows at baseline: 24, anomic; 4,
features. Altogether, pragmatic difficulties including fail- transcortical sensory; and 3, Wernicke’s aphasia. The last
ure of topic maintenance, perseveration, and failure to switch visit classification changed to mostly Wernicke’s and trans-
speaker roles, were present in 35 of 37 patients (Table 1). cortical sensory aphasia. Surface dyslexia and dys-
Semantic substitutions in spontaneous speech were fre- graphia (patients retain phonological processing and regu-
quent in SD (54.1%) when compared with PNFA (7.5%; larize words when they cannot read or write them by
2
=24.9; P=.001) but phonological paraphasias were ab- meaning), elicited by reading and writing irregular words,
sent in SD and frequent in PNFA (41.5%; 2 =20.3; P=.001), was observed in 18 of 19 patients with SD (Table 1).
a significant double dissociation. Fifteen of the patients with
PNFA were nonfluent, scoring 5 or less on the standard- BEHAVIOR
ized fluency rating of the WAB. Another 10 had aphemia,
stuttering, or apraxia of speech; some were only anomic Only 6 cases presented with relatively pure SD without
and logopenic at the time of first examination but none had behavioral change. All but 2 of these cases developed the
clinically significant comprehension or semantic diffi- behavioral features eventually. One died of motor neu-
culty. Questioning the meaning of words heard in conver- ron disease a year after being seen; the other was lost to
sation was typical and occurred in 34 of 37 of the patients follow-up. In 16 of 37 patients, the behavioral symp-
with SD. This feature was recorded in 4 of 6 of the autop- toms were noticed first (Table 1). On the Frontal Behav-
sied SD cases and was not seen in any other groups (Table 1). ioral Inventory, the bvFTD and SD groups scored sig-
nificantly higher (more behavioral abnormality) than the
LANGUAGE PNFA and AD groups.22 Item analysis of the Frontal Be-
havioral Inventory that compared the SD and bvFTD
The Figure shows the results of the quantitative as- groups is summarized in Table 3. Only apathy, aspon-
pects of language performance on the WAB, comparing taneity (closely related), and personal neglect differed sig-

486

nificantly between the two groups. These are all nega-
tive items (deficiency behaviors). When all of the negative Table 3. Scores of Patients With SD and bvFTD on Items
(Table 3) items are combined in a subscale, the SD group of the Frontal Behavioral Inventory
scored significantly lower (better) than bvFTD group
Mean (SD)
(t63 =−3.945; P .001; effect size [d]=0.97), a large effect. P
Whereas, on the positive subscale (disinhibition or ex- FBI Item SD bvFTD Value
cess behaviors, the other 12 items), the difference be- Apathy a 1.16 (1.24) 2.09 (1.06) .002
tween the groups was moderate (t63 = −2.050; P = .04; Aspontaneity a 1.20 (1.30) 2.24 (0.92) .001
d=0.51). Indifference 1.13 (1.23) 1.85 (1.08) .01
Inflexibility 1.61 (1.31) 1.85 (1.02) .41
Personal neglect a 0.87 (1.06) 1.91 (1.08) .001
COMMENT Disorganization 1.94 (1.03) 2.50 (0.79) .02
Inattention 2.06 (1.06) 2.21 (1.01) .58
Loss of insight 1.35 (1.36) 2.09 (1.11) .02
The diagnosis of SD is far from unequivocally defined or Perseverations/obsessions 1.87 (1.20) 2.09 (1.03) .44
universally practiced. Numerous studies have ap- Irritability 1.13 (1.15) 1.68 (1.25) .07
proached theoretical issues exploring semantic memory Jocularity 0.84 (1.13) 0.97 (1.17) .65
using a few patients with SD at a time. We focused on Poor judgment/impulsivity 1.42 (1.20) 1.57 (0.98) .57
Inappropriateness 1.71 (1.32) 2.03 (1.03) .28
the clinical features and quantitation of language and be-
Restlessness/roaming 1.10 (1.16) 1.44 (1.28) .26
havior in a larger cohort. Although the language results Aggression 0.84 (1.16) 1.00 (1.23) .59
could be considered circular, because SD was defined by Hyperorality 0.84 (1.10) 1.71 (1.24) .004
fluent speech and poor comprehension, patient selec- Hypersexuality 0.45 (0.96) 0.59 (1.08) .59
tion was based on caregiver history and neurocognitive Utilization 0.52 (0.89) 0.59 (1.02) .76
examination; language and behavioral quantitation, neu- Incontinence 0.23 (0.68) 0.62 (1.04) .09
ropsychological tests, and imaging were performed in- Hoarding 0.89 (0.89) 1.08 (1.08) .24
dependently.
Abbreviations: bvFTD, behavioral frontotemporal dementia; FBI, Frontal
Semantic dementia should be suspected when a pa- Behavioral Inventory; SD, semantic dementia.
tient with progressive aphasia has significant or early dif- a Indicates significant difference after Bonferroni corrections; P .002.

ficulty with single-word comprehension.1,12,23 The se-
mantic loss becomes clinically evident when the patient
questions the meaning of words, usually nouns in con- erature; one has increasing loss of word meaning while
versation. The “What is . . . ?” questioning was fre- the other has significant loss of syntax.12,25 We also docu-
quently observed in the population with SD, and it ap- mented the high frequency of surface dyslexia, confirm-
pears to be a highly diagnostic feature because it was ing the loss of reading of irregular words by the seman-
absent in all other patient groups. This is even more strik- tic route.12,26
ing considering patients demonstrated preserved repeti- The fluency-nonfluency distinction is controversial and
tion and phonological competence, eg, “Gorilla? . . . go- rarely based on a standardized, scorable scale such as in
rilla . . . what is gorilla?” Naming was the worst in our our study. A recent editorial warned against such an over-
SD group, confirming that it is a major, albeit less spe- simplified dichotomy of progressive aphasia.27 There are
cific, feature.1,12,23 Patients with AD also forget words early, different definitions of fluency28,29 or logopenia.29 Fur-
perform poorly on naming tests, and substitute words from thermore, fluency is stage related,16,20 and 4 of 6 of our
the same semantic or superordinate category. autopsied patients with SD were recorded to be nonflu-
A most remarkable feature in our SD cohort was the ent or mute eventually. Particularly problematic is the
severe pragmatic disturbance with garrulous, excessive, inclusion of all fluent aphasics as having SD, potentially
disinhibited output, stereotypic thematic perseveration, resulting in including patients with early PNFA or AD
and semantic jargon. Persevering with their own agenda in SD groups. Recent usage includes SD under the pri-
and not stopping to listen are features that distinguish mary progressive aphasia umbrella, in addition to PNFA
early SD from PNFA and AD. Others have explored sin- and logopenic progressive aphasia, which turns out to
gular aspects of pragmatics such as coherence in SD.24 be aphasic AD in many cases.29-31 Some ambiguous cases
The conversational peculiarity appears early but the ca- have been called mixed progressive aphasia.31 This cat-
sual observer may not notice it. Later it may be com- egory is similar to our designation of possible SD in this
pounded, even overshadowed by the altered personality study or possible primary progressive aphasia previ-
and unacceptable behavior, although it contributes sig- ously.20 Semantic paraphasias were characteristic of SD
nificantly to the social handicap. and phonological ones of PNFA, confirming other stud-
A comprehensive yet practical-length language test ies12,28 and demonstrating a double dissociation. Phono-
such as the WAB is helpful to quantify fluency, compre- logical paraphasias, however, are also a feature of logo-
hension, repetition, naming, reading, and writing and to penic progressive aphasia29 and develop in later stages
follow the course of the illness.17 Formal testing of com- of AD.15
prehension with the WAB or verbal intelligence tests may In our study, one-third of our patients with SD
alert the examiner to SD. Word comprehension was un- (Table 1) had clinically evident visual object use agno-
impaired in PNFA initially. Sentence comprehension was sia and prosopagnosia in addition to the language defi-
impaired in both patients with SD and PNFA but each cit. Caregivers often described loss of object recognition
may have different mechanisms, as suggested in the lit- beyond word finding or naming impairment, usually

487

manifesting as difficulty finding an object in their sight Greater left than right temporal atrophy has been pre-
or not knowing how to use it. Visual, face, and sound viously described as characteristic of SD1,12,37; our data
agnosia as well as the behavioral abnormality have been confirm this. Marked temporal atrophy should alert the
associated with right temporal involvement and language- clinician to the diagnosis. There are exceptions, how-
predominant symptoms with left temporal atrophy.32 Vi- ever, suggesting that neuroimaging should be used as an
sual agnosia can also be a feature of posterior cortical at- adjunct rather than primary diagnostic criterion. Neu-
rophy, which most often has AD pathology but the roimaging is also stage related and, eventually, both tem-
apperceptive deficit and the presence of Balint syn- poral lobes and frontal areas become involved.40
drome distinguished that condition from SD.33 The underlying pathology is most often ubiquitin
The association of SD with the behavioral manifesta- positive. 19,37,41 In our series, 5 of 6 autopsies had
tions of FTD occurred with few exceptions. This has been ubiquitin-positive, tau-negative inclusions and 1 had
previously recognized to a variable extent34,35 but, in our dementia that lacked distinctive histopathology. Recent
opinion, it has not received enough emphasis. In some studies suggested an association with more neuritic
studies, SD often appears as a separate syndrome and little, ubiquitin deposits with few cytoplasmic inclusions.19 So
if any, mention is made of the behavioral abnormalities. far we do not have sufficient data to confirm or contra-
We have previously shown that the presence of more than dict this correlation.
one Pick complex syndrome (eg, disinhibition plus apha- In conclusion, the cardinal diagnostic features of SD
sia) is associated with FTD rather than other pathology based on our findings are (1) the questioning of the mean-
at autopsy.36 In another study of SD, the presence of being of words, which is a striking manifestation of the com-
havioral change also seemed to correspond to the pres- prehension deficit of single nouns (SD may be called the
ence of FTD pathology.37 Others consider the behav- “What is . . . ?” disease after this singularly characteris-
ioral abnormalities in SD to be distinct from those of tic clue); (2) garrulous, empty, fluent speech output with
bvFTD.34 For example, patients with SD have food fads thematic perseveration and semantic jargon; and (3) the
and are social seekers, while patients with bvFTD have strong association between SD and bvFTD—the two pre-
gluttony and social avoidance.34 We also found on item sentations often converge.
analysis that negative symptoms such as apathy and per- The equation with all fluent aphasia is an overinclu-
sonal neglect were more severe in bvFTD, but the dis- sive dilution of a clinically and possibly biologically dis-
inhibition items were involved more similarly. This sug- tinct presentation. The overlap with aphasic AD, logo-
gests a different involvement of the medial frontal penic progressive aphasia, and early PNFA creates
cingulate and the anterior temporal orbitofrontal cir- diagnostic uncertainties until the characteristic features
cuits earlier in the disease. Semantic dementia without of SD emerge. Nevertheless, the identification of SD is
behavioral impairment may appear early in the illness. valuable, particularly in view of the recent advances in
On the other hand, SD often appears secondarily to bvFTD pathology and molecular biology of FTD that suggest a
and remains underdiagnosed. From our longitudinal co- potential for specific treatment of different varieties of
hort study of FTD,20 only patients with bvFTD devel- the presentation.
oped SD later (approximately 20%). Conversely, more
patients with SD (76%) developed bvFTD as a second- Accepted for Publication: July 15, 2009.
ary syndrome compared with other presentations, sug- Correspondence: Andrew Kertesz, MD, Department of
gesting an association of bvFTD with SD.20 In the pres- Cognitive Neurology, University of Western Ontario, 268
ent study, the Frontal Behavioral Inventory, as expected, Grosvenor St, London, ON N6A 4V2 (andrew.kertesz
showed the greatest behavior impairment in the bvFTD @sjhc.london.on.ca).
group. Nonetheless, the SD group also obtained higher Author Contributions: Study concept and design: Kertesz.
scores (more behavioral abnormalities) compared with Acquisition of data: Kertesz, Jesso, Harciarek, Blair, and
AD and PNFA. McMonagle. Analysis and interpretation of data: Kertesz,
In this study, patients with SD and PNFA performed Jesso, Blair, and McMonagle. Drafting of the manuscript:
worse than the other groups on the Mini-Mental State Kertesz, Jesso, Harciarek, and McMonagle. Critical revi-
Examination and the Dementia Rating Scale because these sion of the manuscript for important intellectual content:
tests have significant language components. Clinically, Kertesz, Harciarek, Blair, and McMonagle. Statistical analy-
these patients are more aphasic than demented. Al- sis: Kertesz, Jesso, Harciarek, and Blair. Obtained funding:
though episodic and nonverbal visuospatial memory is Kertesz. Administrative, technical, and material support:
preserved in SD,12 family reports of forgetfulness of names Kertesz, Jesso, and McMonagle. Study supervision: Kertesz.
were common (28 of 37 in Table 1). Poor performance Funding/Support: This study was supported by the Law-
on verbal memory tests related to verbal semantic loss son Research Institute and the Medical Research Coun-
and reversal of the temporal gradient for episodic memory cil of Canada Cohort study (ACCORD); and a START
in SD has been observed by others.38,39 The present study scholarship from the Foundation for Polish Science (Dr
also indicates that the category fluency is significantly Harciarek).
worse in the SD group, likely owing to lexicosemantic Financial Disclosure: Dr Kertesz reports receiving grants
rather than executive dysfunction. The incidence of SD for pharmaceutical trials by Janssen-Ortho (Galan-
was estimated in one clinic as 25% in the FTD popula- tamine in Frontotemporal dementia), for clinical trials
tion12 vs 10% in ours. This may reflect differences in se- in Alzheimer disease by Pfizer, Myriad, Lundbeck, and
lection or referral but incidence data from a well- GlaxoSmithKline, and serving on the advisory board of
designed epidemiological study are lacking. Pfizer.

488

22. Kertesz A, Davidson W, Fox H. Frontal behavioral inventory: diagnostic criteria
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