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 |