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Table 1 Studies Examining LTM Skills in Individuals with DS Organized by Age Group and Presented Chronologically

From: Memory profiles in Down syndrome across development: a review of memory abilities through the lifespan

Study Comparison Group Matching Assessment CA of DS group (Yrs) MA of DS group (Yrs) Task Findings
Preschool studies (< 5 years old)
Milojevich 2015 [54] MA-matched TD Bayley- III M = 2.75
(Range 1- 4)
M = 0.9 Visual LTM
Deferred Imitation
DS ~ TD-MA on number of target actions after 1 month delay
DS < TD-MA temporal sequence of actions after 1 month delay
TD-MA: Familiar target actions > Novel target actions
DS: Familiar target actions ~ Novel target actions
Roberts 2015 [35] Verbal MA-matched TD MSEL
(Verbal scales)
M= 4
(Range 3-5)
M = 2.8 Visual LTM
Deferred Imitation Task
Object Location Retention task
DS > TD-Verbal MA
DS ~ TD-Verbal MA
(Results same when groups matched on nonverbal ability)
School Age and Adolescent studies (6 to 17 years old)
 Carlesimo 1997 [56] ID group
MA-matched TD
WISC-R or
WAIS
M=16 M = 9.1 Verbal and Visual LTM
Word List Learning
Story Recall
Word Recognition
Rey Figure Form B
DS < ID < TD-MA on immediate & delayed recall
DS < ID < TD-MA
DS < TD-MA; DS~ID on hit rate and false alarms
DS < TD-MA; DS~ID on immediate & delayed recall
 Mattson 1999 [59] TD & FAS -- M=12.9
(Range = 9.3-16.0)
-- Verbal LTM
Word Recall
Word Recognition
DS < FAS < TD
DS < FAS < TD
 Dawson 2001 [157] MA - matched TD & ASD Preschool Language Scale-3 M=5.7 M=2.5 Visual LTM
Visual Paired Comparison (5-minute delay)
DS ~ TD-MA
DS ~ ASD
 Byrne 2002 [60] Reading Matched & Average TD
Readers
BAS Word Reading M=8
(Range= 4-12)
M=6.3 Visual LTM
Delayed Visual Recall
DS < TD-RM and TD-AR
*All 3 groups showed steady progress in their memory abilities. Groups did not significantly differ in amount of progress made over the two years
Pennington 2003 [9] MA-matched TD DAS M=14
(Range=11-19)
M=4.5 Verbal, Spatial, Visual LTM
List Learning
Maze Learning task
Pattern Recognition
Paired Associates Learning
Ecological Memory task
DS < TD-MA
DS < TD-MA
DS < TD-MA
DS < TD-MA
DS < TD-MA on some aspects of task; DS~TD-MA on other aspects
 Nichols 2004 [57] MA-matched TD
SLI
WS
Focal Lesions
WISC-R or WAIS-R M=15.0 M=7.9 Verbal LTM
CVLT-C
Long Delay Free Recall: DS<TD-MA; DS~WS, SLI
Number of Intrusions: DS > TD-MA, FL
Recognition Memory/Discriminability: DS < TD-MA; DS~WS, SLI
 Bird 2004 [158] NVMA-matched TD SB M=16.4
(Range=12 -20)
M=5.4 Verbal LTM
Immediate & Delayed Story Recall
(with embedded novel, nonsense words)
DS<TD-NVMA on immediate not delayed verbatim story recall
(which included nonsense words)
Vicari 2005 [62] MA-matched TD SB M=16
(Range=8-30)
M=5.3 Visual and Spatial LTM
Visual-Object Learning
Visual-Spatial Learning
DS < TD-MA
DS ~ TD-MA
 Jarrold, 2007 [55] WS group
TD
Not matched M=13
(Range=10-16)
M=5.3 Verbal and Visual LTM
People Test – verbal recall
Shapes Test – visual recall
DS ~ TD
DS < TD; DS~WS
Visu-Petra 2007 [120] MA-matched TD SB M=14
(Range=8-21)
M=5.75 Visual & Spatial LTM
Delayed Match to Sample
Paired Associates Learning Number of Stages Completed
Spatial Recognition Memory
DS < TD-MA
DS < TD-MA
DS < TD-MA
 Edgin 2010 [25] IQ-matched WS group WASI M=17.8 -- Verbal and Visual LTM
NEPSY List Learning
CANTAB Paired Associates Number of Stages Completed
DS > WS
DS > WS
 Heimann 2016 [61] TD,
Language- matched ASD
-- M=5.25 (SD=1.03) M=2.63 (SD=.72) Visual LTM
Deferred Imitation
DS ~ TD
DS > ASD
Adult and Older adult studies (18 years and older)
 Dalton 1974 [159] Young and Old ID group -- Young M= 20.9 Intermediate M=41.7
Old M= 50.8 (Range=19-58)
-- Visual LTM
Delayed Matching to Sample
Young DS < Young & Old ID; Young DS = Intermediate DS
Intermediate DS < Old ID; Intermediate DS = Young ID
Old DS < all other DS and ID groups
 Varnhagen 1987 [64] IQ-matched ID group SB M=22.70
(Range=19-25)
M=4.78 Verbal LTM
Lexical Access – a measure of lexical LTM access derived from verbal measures
DS < ~ ID (p=.06)
 Ellis 1989 [160] TD group
(matched roughly on CA)
-- M=26.8
(Range=14-51)
-- Visual LTM
Picture Recall
Picture Location Recall
DS < TD college students
DS < TD college students
 Devenny 1992 [161] ID < 35
ID > 35
- Young DS M=31.7
Old DS M=41.8
- Verbal LTM
Selective Reminding Test
Both TD and DS participants showed no significant change in performance from Time 1 to Time 2
 Brugge 1994 [63] CA-matched ID group -- M=31
(Range=22-51)
-- Verbal LTM
CVLT
DS<ID on various scores
CVLT Short Delay Savings score predictive of group.
DS performance inversely related to age
 Simon 1995 [70] IQ-matched ID &
CA-matched TD
-- M=30 -- Verbal and Visual LTM
Word Recall
Facial Recognition
Picture Recall
DS < TD-CA; DS~ID
DS ~ ID; DS<TD-CA
DS < ID & TD-CA
 Devenny 1996 [65] Young DS
(CA 30-39)
Middle-Aged DS (CA 40-49)
Old DS
(CA 50+)
ID group with similar IQ & Age
Subtests of WISC-R were used to estimate IQ Young DS M=37
Middle-Aged DS M=45
Older DS M=55
- Verbal LTM
Selective Reminding Test (SRT)– word recall
Participants were tested at 6 time points across 5 years
DS: Less improvement than ID on repeated testing
Young DS ~ Improvement on SRT across time points
Middle-Aged and Older DS ~ Decrease in SRT across time points
*Note: This study focused on a more mildly impacted subgroup of adults with DS
 Dulaney 1996 [71] CA- matched TD; ID -- M=33.6 (SD=6.8) -- Visual & Spatial LTM
Picture Recognition
Spatial Location Recall of pictures
DS < TD-CA; DS ~ ID
DS < TD-CA; DS ~ ID
Vicari 2000 [36] MA-matched TD SB M= 21 M=6.5 Verbal and Visual LTM
Word Recall
Picture Recognition
Spatial Sequence Learning
DS <TD-MA on word recall; DS > TD-MA on false alarms
DS < TD-MA on picture recognition; DS > TD-MA on false alarms
DS > TD-MA on number of trials to learn sequence *higher number of trials indicates worse performance
 Krinsky-McHale 2005 [162] IQ Matched WS
ID
  M=44.36 (SD=5.56)   Verbal LTM
Selective Reminding Task
For both DS and WS, number of words recalled decreased with age; not observed in ID group
Davis 2014 [67] MA-matched TD and ID Leiter-Revised Brief Form
& KBIT-2
M~18 M=5.0 Spatial LTM
Route Learning Recall
DS< TD-MA & ID
 Purser 2015 [69] WS group
TD group
(similar mental age)
-- M=18
(Range=10-39)
-- Visual Spatial LTM
Route Learning Task – Errors
DS > TD & WS (errors)
 Lavenex 2015 [68] NV MA-matched TD Leiter-Revised M=18.8
(Range=11-29)
M=5.3 Spatial LTM
Allocentric Spatial Memory Task
DS<TD-MA
Within DS Group Comparisons of Older Adults
 Haxby 1989 [163] 35+ DS
(4 with dementia)
Under 35 DS
-- Under 35 M=26
35+ non-demented M=48
35+ demented
M=57
Under 35 M= 6.1
35+ non-demented M=4.3
35+ demented M=2.5
Visual LTM
Hidden Object Memory
Recognition for Designs
35+ Non-demented DS < Under 35 DS; demented DS not compared
All 35+ DS (demented & non-demented) < Under 35 DS
 Alexander 1997 [66] Young DS
(CA 22-38)
Old DS without dementia
(CA 41-61)
-- Young DS M=30.1
Old DS M=47.4
Young DS M=5.7
Old DS M=4.7
Visual LTM
Hidden Object Memory
(10-second delay)
Hidden Object Memory
(2-minute delay)
Old DS < Young DS
Old DS < Young DS
 Crayton 1998 [72] Young DS (CA Under 40)
Middle-Aged DS (CA 40-49)
Older DS
(CA 50+)
-- -- M =4.8
(for whole group on BPVS)
Visual and Spatial LTM
Pattern Recognition
Spatial Recognition
Delayed Associative learning
Young DS ~ Middle-Aged DS ~ Older DS
Middle Aged DS < Young DS
Older DS < Young DS
 Hon 1998 [73] Young DS
(CA 30-44)
Old DS
(CA 45-65)
- 10 with AD
-- Overall M=42.6 -- Verbal and Visual LTM
Rivermead - Name Learning
Rivermead - Face Learning
Rivermead - Route Learning
Rivermead- Story Recall
Old DS < Young DS
Old DS < Young DS
Old DS < Young DS
Old DS < Young DS
 Dalton 1999 [164] Young DS (CA 17-39)
Old DS (CA 40-58)
-- -- -- Visual LTM
Matching to Sample
(25 second delay)
Old DS < Young DS
 Krinsky-McHale 2002 [18] DS with dementia (DS+DAT)
DS without Dementia (DS)
  DS+DAT
Females M=52.23
Males M-45.32
DS
Females M=42.06
Males M=44.36
-- Verbal LTM
Selective Reminding Test
(word list recall)
DS+DAT greater decline in performance over 3 years relative to DS
Older DS+DAT & DS greater decline in performance over 3 years than Younger DS & DS+DAT
 Devenny 2002 [165] -- -- DS no DAT=47.3, DS DAT= 54.8 -- Visual LTM
Cued Recall Task
DS DAT < DS no DAT
  1. Key: Comparison Groups: CA chronological age, DAT Dementia of the Alzheimer’s Type, DS Down Syndrome, ID Intellectual Disability, MA mental-age, NVMA Nonverbal mental-age, RA-matched reading age matched, SLI Specific Language Impairment, TBI Traumatic Brain Injury, TD typically developing, WS William’s Syndrome
  2. Tests: BAS British Abilities Scale, Bayley Bayley Scales of Infant Development, BPVS British Picture Vocabulary Scale, CANTAB Cambridge Neuropsychological Test Automated Battery, CVLT-C California Verbal Learning Testing Children’s Version, DAS Differential Ability Scales, K-BIT Kaufman-Brief Intelligence Test, Leiter Leiter International Performance Scale, MSEL Mullen Scales of Early learning, RCPM Raven’s Coloured Progressive Matrices, Rivermead Rivermead Behavioral Memory Test for Children, SB Stanford Binet Intelligence Scale, WAIS-R Wechsler Adult Intelligence Scale-Revised, WASI Wechsler Abbreviated Scale of Intelligence, WISC-R Wechsler Intelligence Scale for Children- Revised
  3. Note: Italicized authors’ names indicate studies included in effect size analyses