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