with the increasing elderly population , dementia has become one of the most common social 
 problems1 .
because memory impairment is 
 the core symptom of dementia , the majority of early interventions aim to slow cognitive 
 decline . in recent years
however , studies into their use 
 for dementia patients have found them to have limited effectiveness3 .
recent studies , however , have focused on 
 non - pharmacological cognitive interventions to alleviate the cognitive deficits related to 
 dementia4 , 5 .
non - pharmacological cognitive interventions for dementia include re - learning strategies 
 that promote the management ability to reduce cognitive impairment3 , 6 .
cognitive 
 interventions differ from pharmacological interventions in that they consider the 
 interaction between the patients and therapist , as well as the needs of the patient7 .
cognitive interventions have been shown to 
 temporarily slow the rate of cognitive decline and the loss of functional abilities .
on the 
 other hand , they can fail because cognitive rehabilitation interventions that are beneficial 
 for the patients with dementia require significant effort and attention . spaced retrieval training ( srt ) is a good candidate strategy for cognitive intervention in 
 dementia because it does not require considerable cognitive effort8 .
srt is an expanded interval timer with independent 
 data - tracking and timing of up to 3 targets4 .
srt recalling targets over increasingly longer periods of time has 
 been proven to result in improved learning in people with mild to moderate dementia .
this 
 training regime was developed based on the expanding rehearsal technique which was 
 originally developed for improving memory in cognitively intact persons9 .
errorless learning ( el ) is a teaching technique that 
 prevents the making of mistakes while subjects are learning a new skill or acquiring new 
 information , and it is conducted together with srt or the vanishing cues technique .
srt with 
 el is a technique for training the memory which uses an expanded interval that increases 
 with correct responses and decreases with incorrect ones10 .
kinsella et al.11 suggested that srt 
 would be beneficial for individuals with dementia because it utilizes the relatively 
 unimpaired automatic implicit memory system .
srt can be used with el because it minimizes 
 the possibility of error during the acquisition phase of learning by ensuring mistakes . in 
 addition
, srt has a spacing effect that is retrieved more effectively when trials are 
 distributed over time .
srt appears to be attracting attention within the field of dementia 
 treatment because of these advantages12 , 13 .
non - pharmacological interventions for dementia , such as music , art , physical activity , and 
 gardening , are often performed , but cognitive intervention of srt with el has rarely been 
 conducted in clinical settings . in particular , studies aimed at observing the effects of srt 
 in a clinical environment are difficult to perform . therefore , the purpose of this study was 
 to examine effects of srt with errorless learning ( el ) for the rehabilitation of patients 
 with dementia .
twenty - nine participants with vascular dementia ( vd ) and alzheimer s disease ( ad ) 
 participated in the present study .
the study participants were enrolled from among 
 inpatients in a rehabilitation - care hospital of korea .
all the subjects provided their 
 written informed consent to participation in the experiment in accordance with the ethical 
 principles of the declaration of helsinki .
subjects diagnosed with dementia including major 
 depressive disorder by the dsm - iv criteria and those with serious medical and neurological 
 problems that could have affected their mental function were excluded .
table 1table 1.general characteristics of the subjects ( n=29)characteristicsvd ( n=22)ad ( n=7)gender ( male / female)13/92/5age ( years)58.99.978.14.4education ( years)7.95.01.72.9mmse - kc15.75.19.23.2gds - k18.85.615.53.4vd : vascular dementia ; ad : alzheimer dementia ; mmse - kc : korean version of mini mental 
 status evaluation in the cerad - k assessment packet , gds - k : korean version of geriatric 
 depression scale lists the general characteristics of the 29 participants .
the ad group had a 
 higher average age than the vd group , and had lower mean values in the korean version of 
 mini - mental status evaluation ( mmse - kc ) , and the korean version of geriatric depression 
 scale ( gds - k ) , as well as lower education levels than the vd group .
vd : vascular dementia ; ad : alzheimer dementia ; mmse - kc : korean version of mini mental 
 status evaluation in the cerad - k assessment packet , gds - k : korean version of geriatric 
 depression scale mmse - kc was used to provide an index of the current cognitive status14 . the maximum score on mmse -
this measure consists of 30 
 items with each item scoring 1 point , and higher total scores indicate a higher level of 
 depression .
the cognitive functions were investigated using the korean version of the 
 consortium to establish a registry for the alzheimer s disease ( cerad - k ) battery , which 
 consists of 8 subtests16 .
the 
 independence of activities of daily living ( adl ) was examined using the modified barthel 
 index which consists of 10 subtests .
the srt with el was administered by first providing the patients with a prompt question and 
 associated target response .
when successful at recalling the response , the patient was 
 required to recall the target information at longer inter - trial intervals .
if at any time 
 the patient was unable to recall the response , they were provided with the information and 
 asked to repeat it .
the training was considered successful if the patient correctly 
 responded to the prompt question at the beginning of each session ( 45 , 90 , 180 , 360 , and 720 
 sec . ) .
all words were 
 composed of 100 different words presented as high frequency words by the national institute 
 of the korean language .
if a subject repeatedly failed to remember a word for 45 seconds , 
 the subject was excluded . if the subject remembered the word in two sessions ( 720 sec .
 2 
 session ) , the number of words added ranged from one to five . during each interval , the 
 subject was asked to perform inter - retrieval activities in order to prevent them from 
 rehearsing the given set of words .
the inter - retrieval activities consisted of simple 
 physical activities that did not require much memory function ( e.g. , jenga , puzzle , 
 pegboards ) .
spss for windows version 18.0 was used for the statistical analysis , and p values less than 
 0.05 were considered significant .
wilcoxon s matched - pairs signed - rank test was used to 
 compare the pre- and post - test neuropsychological , depression , and adl performances of each 
 group .
as listed in table 2table 2.comparison of the effect of srt on cerad - k of dementia patientsvd group ( n=22)ad group ( n=7)beforeafterbeforeafterverbal fluency test5.822.747.183.13 * 3.291.604.292.56boston naming test7.413.208.143.11**3.712.143.572.30mmse - kc15.735.1717.274.65**9.293.2510.004.32word list memory8.823.8410.774.46 * 2.573.552.863.80constructional praxis6.002.916.143.315.711.985.712.06word list recall2.451.743.361.87**0.861.570.861.57word list recognition4.363.035.683.47 * 1.861.951.292.21constructional recall2.412.523.642.36**0.431.130.431.13srt : spaced retrieval training ; cerad - k : korean version of consortium to establish a 
 registry of alzheimer s disease ; vd : vascular dementia ; ad : alzheimer dementia ; values 
 are expressed as mean  sd .
significant difference from pre - test , * p<0.05 , * * 
 p<0.01 , all items of the cerad - k score in the vd group except for constructional 
 praxis increased significantly after the srt with el intervention , but their values were 
 similar to those of the ad group .
significant differences were observed in the gain of the 
 verbal fluency test , the boston naming test , mmse - kc , word list memory , word list recall , 
 word list recognition , and constructional recall in the vd group between before and after 
 the intervention . there were no significant differences in the subtests in the ad group 
 between before and after the intervention .
srt : spaced retrieval training ; cerad - k : korean version of consortium to establish a 
 registry of alzheimer s disease ; vd : vascular dementia ; ad : alzheimer dementia ; values 
 are expressed as mean  sd . significant difference from pre - test , * p<0.05 , * * 
 p<0.01   table 3table 3.comparison of the changes in gds - k and mbi between before and after the 
 interventionvd group ( n=22)ad group ( n=7)beforeafterbeforeaftergds - k18.85.617.26.1 * 15.53.417.84.5mbi57.216.557.316.791.24.190.84.0gds - k : korean version of the geriatric depression scale ; mbi : modified barthel index ; 
 values are expressed as mean  sd .
significant difference from pre - test , * 
 p<0.05 compares the effects of the srt on gds - k and mbi of the dementia groups .
gds - k : korean version of the geriatric depression scale ; mbi : modified barthel index ; 
 values are expressed as mean  sd .
the subjects with 
 dementia could perform the srt with el . in particular , the srt with el intervention was 
 beneficial for the vd patients .
this suggests that the cognitive ability of dementia 
 patients may be improved by srt with el .
previous studies have shown that dementia patients have decreased communication skills and 
 voluntary activity because of their reduced cognitive function .
therefore , it is more 
 difficult for dementia patients to have interpersonal relationships and engage in social 
 participation17 .
cognitive 
 interventions are essential to maintain the motivation for community participation . in 
 addition , they are required for enhancing memory in cognitive interventions . considerable 
 research has focused on the efficacy of cognitive intervention in rehabilitation .
the in - session maximum retention span was maintained at 720 seconds during srt for the vd 
 and ad groups .
in addition , the intervention time was set at 30 minutes , considering the 
 clinical environment and the disease characteristics .
srt was previously administered in an 
 in - session retention span of 1,440 seconds for mild dementia , but 720 seconds was used in 
 the present study because of the various characteristics of dementia .
srt with el had a significant effect on the performance of the vd group in the cerad - k 
 except for the item of constructional praxis .
after the srt with el , the vd group showed 
 superior cognitive performance compared to the post - test values of the ad group .
findings 
 similar to those of the vd group have been reported by previous studies19 . although not statistically significant , srt with el as a 
 cognitive approach elicited improvements in the ad group . moreover , increasing the number of 
 target words during the srt intervention may enhance the memory function in the early stages 
 of ad , and might improve the acquisition of new information by patients with dementia20 .
it is our opinion that this is due to the difficulty in 
 accurately calculating individual effect sizes for the adls .
mbi has limited ability to 
 compare the changes in the performance of patients with dementia after a short training 
 period .
a limitation of the present study is that the changes were not compared with another 
 dementia group .
while there were before and after changes in the vd and ad groups , it was 
 difficult to identify differences between the groups .
therefore , additional research will be 
 needed to determine the effects of srt on ad patients according to the method of 
 intervention .
future research using sufficient sample sizes will be needed to obtain strong 
 evidence for its efficacy not only in pre- and post - test results , but also between 
 groups .
 [ purpose ] among the non - pharmacological interventions for dementia , spaced retrieval 
 training ( srt ) is a good method for rehabilitating cognition . 
 the purpose of this study 
 was to examine effects of srt with errorless learning ( el ) in the rehabilitation of 
 patients with dementia . 
 [ subjects and methods ] twenty - nine participants with vascular 
 dementia ( vd ) and alzheimer s disease ( ad ) participated in the present study . the korean 
 version of the consortium to establish a registry for alzheimer s disease ( cerad - k ) and 
 modified barthel index ( mbi ) were performed to assess the changes in the 
 neuropsychological performance and the independent activities of daily living after srt 
 with el . 
 all tests were administered both before and after srt with el . 
 each srt with el 
 intervention was performed for 30 minutes per day for 5 weeks . 
 spss for windows version 
 18.0 was used for statistical analysis . 
 [ results ] all items of the cerad - k score of the vd 
 group except for constructional praxis increased significantly after the srt with el 
 intervention , but no significant differences from the ad group were found . 
 the korean 
 version of the geriatric depression scale ( gds - k ) of the vd group increased significantly 
 after the srt with el intervention . 
 the mean mbi scores of each group showed no 
 significant difference after the intervention . 
 [ conclusion ] srt with el is an effective 
 intervention for memory training of patients with dementia . 
 future research using 
 sufficient sample sizes will be needed to obtain strong evidence for comparing not only 
 the before and after intervention data but also between the groups . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION