several cognitive domains , including attention , memory , and executive functions are impaired in bipolar disorder ( 1 , 2 ) .
meanwhile , in recent decades , there has been an increasing tendency to study neurocognitive deficits like executive functions among researches ( 3 ) .
executive functions are a series of problem - solving tasks to achieve specific goals ( 4 ) , including abilities like attention , reasoning , planning , working memory , response inhibition , and interfering factors control .
disruption in these functions of often ten causes psychiatric or behavioral disorders , suggesting their important role in human complex behavior ( 5 ) .
executive functions are hypothesized in explanation of many disorders such as schizophrenia ( 6 ) , obsessive - compulsive disorder ( 7 ) , autistic disorder ( 8) , eating disorders ( 9 ) , panic disorder ( 10 ) , and posttraumatic stress disorder ( 11 ) .
in fact , quite enough studies have repeatedly shown that bipolar patients suffer from cognitive impairments both during acute phases ( 13 ) and remission / euthymic periods ( 14 , 15 ) .
( 12 ) on 26 studies ( 689 patients and 721 controls ) , suggested that aspects of executive function had a large effect size ( [ d  0.8 ] indicating marked impairment ) , whereas other cognitive domains , including response inhibition and set shifting had medium effect ( 0.5  d  0.8 ) , and finally verbal fluency , immediate memory , and sustained attention had small effect sizes ( 0.2  d  0.5 ) .
( 12 ) , which added studies on first - degree relatives provided the same results on cognitive impairments for euthymic patients and to lesser degrees , but still significantly different from healthy controls , for first - degree relatives ( 16 ) .   because cognitive impairment appears to occur in the early stages of bipolar disorder and increases both during depressive episodes and after periods of mania
, some researches consider this defect as a state marker ( 17 , 18 ) .
other studies have shown that cognitive deficits exist both after a long symptom - free and controlled subthreshold symptoms ( 12 ) .
a recent research with a considerable follow - up period has also spotted that cognitive deficits are stable features in bipolar patients with normal mood during the next 6 years ( 19 ) . among cognitive deficits in bipolar disorder ,
response inhibition impairment accompanies manic symptoms ( e.g. impulsivity , psychomotor agitation , over - talkativeness , overspending , and risky sexual behavior ) .
some researchers suggest that impulsivity , which includes some defects in response inhibition , is higher in patients with bipolar disorder even during normal mood periods ( 20 , 21 ) .  
cognitive impairments have adverse impacts on functions such as daily activities , job , interpersonal relationships , and quality of life ( 22 ) ; also they have significant correlation with weak psychosocial functioning in the future ( 19 ) .
on the other hand , due to negative psychosocial consequences of cognitive deficits on both patients ' medication compliance ( 13 ) and psychological interventions complementing pharmaceutical treatment ( 23 ) , identification and rehabilitation of these defects stress their particular importance . in other words ,
empowerment of bipolar patients , in terms of psychosocial aspects , has been a major concern for clinicians .  
studies like this can provide mental health practitioners with useful intervention strategies , because investigators soon found that effectiveness of psychosocial interventions in these patients is bound to considering their cognitive limitations ( 24 ) . as a new approach in last few years
, it aims to help these patients by intervening on their basic cognitive components , called neuropsychological remediation or cognitive rehabilitation ( 25 ) . by manipulation of basic cognitive processes
, these interventions are supposed to improve cognitive functions and consequently promote psychosocial functioning of bipolar patients ( 26 ) .  
it seems that despite convincing evidence on cognitive impairments during euthymic periods , more researches are still needed with methodologically solid designs to control confounding factors such as medication , and sub - symptoms effects ( 12 ) ; and applying measures with high sensitivity and specificity for evaluating cognitive elements of bipolar patients ( 16 ) ; as well as using a well - designed battery for assessing cognitive impairments ( 27 ) .
this study aimed to evaluate two executive functions ( working memory and response inhibition ) in euthymic bipolar patients and comparing them to the control group .
our hypothesis is that working memory and response inhibition in euthymic patients are weaker compared to healthy controls .
in this case - control study , 30 patients ( 18 to 45 years ) with bipolar diagnosis admitted to roozbeh psychiatric hospital ( from may to october 2013 ) entered the study and were compared to 30 healthy controls . in patients group ,
25 were manic in which 17 ones had psychotic features ; the other 5 patients had mixed episodes .
the patients were examined within 3 to 4 weeks after symptoms remission ( in euthymic period ) .
after psychiatric evaluation and determining their diagnosis , and obtaining their primary consent , the patients were referred to a researcher .
then the researcher described the study to them and if they wanted to participate in the study , they would be asked to complete a consent form .
after that , they were interviewed using structured clinical interview for dsm - iv for axis ( scid - i ) disorders .
inclusion criteria included age between 18 - 45 years , diagnosis of bipolar disorder based on psychiatrist diagnosis , and scid - i diagnoses .
exclusion criteria consisted of any obvious cognitive disorders , major depressive episode , clinical anxiety , substance abuse , and mental retardation .
all 30 patients were receiving mood stabilizers ; 22 of them were taking anxiolytics ; and 17 took also anti - psychotic .
in addition , the control group was interviewed using scid - i as a diagnostic tool for ruling out psychiatric disorders ; and if they met the criteria for any axis i disorders or a history of these disorders , they were excluded .
participants also matched with the patient group based on age , gender , and degree of education .  
to assess executive functions ( working memory and response inhibition ) , cambridge neuropsychological test automated battery ( cantab ) was applied , which was originally developed at cambridge university in 1980s ( 28 ) and now provided by cambridge cognition ( www.cambridgecognition.com ) .
it is a computer - based cognitive assessment system consisting of 22 neuropsychological tests for various cognitive functions .
these tests are administered to subjects using a touch screen computer with no specific language or culture bound , it is based on the standard cognitive tests that are routinely used in psychological assessment ( 29 ) .
since the tests have no use in diagnosis or determining disorder and are based on comparison with no need to the mean score like other neuropsychological tests , they can be applied without confirming their reliability and validity to reflect between  group differences .
these test kits are validated in a sample of 3000 people . in this study , to assess working memory , swm , ssp , were used and response inhibition was obtained through sst test .
it assesses the ability to retain spatial information and manipulate remembered items in working memory , while the subject performs the task to achieve goals .
the test consists of a series of colored squares ( boxes ) that are displayed on the screen . according to the guidelines , by touching boxes and using a process of elimination ,
token in each of boxes and use them to fill up an empty column on the right hand side of the screen .
thus it seems that in the next item , searches should be limited to boxes that contain blue signs .
this process goes on until all blue signs of the boxes are discovered on the screen .
when the trial ends up , a new one begins ( with new color and position different from previous trials ) .
this test consists of 4 experimental trials and every trial has 3 boxes for search ( the first 4 trials will not be scored ) , then test continues with 4 , 6 , and 8 boxes .
the variables used in swm test include errors ( between - group , within - group , and double errors ) , strategy , and latency ( time from when the task is presented until the participant s first touch for opening the box ) ( 27 ) . in this test ,
when a subject touches a box that blue signs have already been found in , errors ( between - group ) are recorded
. within - group errors include the number of errors occurring within a search , for example , the frequency of selecting a box that had been found empty in previous searches , ( frequency of re - selection the empty box in a trial ) .
double errors are calculated when the participant makes an error ( re - selection of an empty box ) that can simultaneously fall within group error categories .
to start , a predetermined sequence of boxes marked with a blue sign were found to start and when it comes back , the new scouring is to begin .
estimated use of this strategy ( strategic points ) is obtained from the total number of times that participants seek a new one with 6 and 8 boxes .
the high score indicates a poor use of these strategies and a low score indicates an efficient use .
spatial span assesses working memory capacity , which is a visuospatial analogue of the digit span test .
this test measures the ability to remember the location and order of a set of visual stimuli ( white squares ) displayed on the screen .
the number of boxes is increased from 2 at the start of the test to 9 at the end , and sequence and color are changing through the test .
the test is stopped when the participant fails in all 3 trials of a stage .
time span is defined as the highest level that the subject can remember in a trial .
this measurement requires both visual and spatial components representing the ability to store data temporarily or online in order to plan more operations in the future .
this test has 5 variables span length , mean time to first response ( span length 2 ) , mean time to last response ( span length 2 ) , total errors , and total usage errors ( 30 , 31 ) .
, the participant should press the arrow that displayed on the screen ( according to the arrow s left or right direction , the subject should press the corresponding button ) .
this test consists of two sections : in the first one , the participant is introduced to press the left hand button when he sees a left - pointing arrow , and right hand button when seeing a right - pointing arrow .
there is one block of 16 trials for the subject to practice this . in the second section ,
the participant is told to continue pressing buttons when they see the arrows , as before , but , if they hear an auditory signal ( a beep ) , they should withhold their response and not press the button .
this part consists of 4 blocks each containing 16 trials ( total trials : 64 ) .
the variables of sst include 5 items including direction errors on stop and go trials , proportion of successful stops , median correct reaction time on go trials , stop signal delay , and stop signal rt ( 31 ) .
this scale was developed by young , biggs , ziegler , and meyer ( 32 ) for mania evaluation .
this measure rates symptoms of bipolar disorder in mania episode and consists of 9 items .
the scoring scale is based on severity of symptoms ( total score : 60 ) .
there was a high correlation between scores of two independent clinicians on both the total score ( 0.93 ) and the individual item scores ( 0.66 to 0.92 ) ( 32 ) . reliability and validity of this scale were acceptable in an iranian sample ( isfahan province ) ( 33 ) . in this study ,
concordant validity of ymrs with the world health organization world mental health composite international diagnostic interview ( who wmh - cidi ) was 0.87 .
discriminatory analysis results indicated 17.14 and the optimal cut - off point with 98.4% sensitivity and 98.4% specificity .
ymrs ( young mania rating scale ) is a valid instrument with acceptable sensitivity and specificity which can be applied in both clinical and research settings .
its test - retest reliability has been reported between 0.48 to 0.86 and a mean of 0.86 ( 34 ) .
internal consistency of bdi - ii was estimated to be 0.73 - 0.93 and the correlation between parallel forms was 0.89 .
concurrent validity of the questionnaire with the hamilton rating scale for depression ( hrsd ) and depression subscale of scl-90 has been 0.71 and 0.89 , respectively ( 34 ) .
( 35 ) on a persian version of bdi - ii , the test had high internal consistency ( cronbach  = 0.87 ) and acceptable test - retest reliability ( r = 0.74 ) .
this questionnaire consists of 21 multiple choice items ( scoring from 0 to 3 ) , which assesses the severity of anxiety .
three items relate to anxious mood , 3 ones assess specific phobias and other questions evaluate autonomous hyperactivity symptoms and tension .
beck et al . ( 36 ) have reported the internal consistency of this scale as 0.93 and its test - retest reliability as 0.75 .
this questionnaire was validated in iran by kaviani and mousavi ( 37 ) . in their study ,
internal consistency measured by cronbach  was 0.92 ; test - retest reliability was 0.83 and within class validity was 0.83 .
independent t - test was applied to assess differences between means considering p < 0.05 significant level .
to assess executive functions ( working memory and response inhibition ) , cambridge neuropsychological test automated battery ( cantab ) was applied , which was originally developed at cambridge university in 1980s ( 28 ) and now provided by cambridge cognition ( www.cambridgecognition.com ) .
it is a computer - based cognitive assessment system consisting of 22 neuropsychological tests for various cognitive functions .
these tests are administered to subjects using a touch screen computer with no specific language or culture bound , it is based on the standard cognitive tests that are routinely used in psychological assessment ( 29 ) .
since the tests have no use in diagnosis or determining disorder and are based on comparison with no need to the mean score like other neuropsychological tests , they can be applied without confirming their reliability and validity to reflect between  group differences .
these test kits are validated in a sample of 3000 people . in this study , to assess working memory , swm , ssp , were used and response inhibition was obtained through sst test .
it assesses the ability to retain spatial information and manipulate remembered items in working memory , while the subject performs the task to achieve goals .
the test consists of a series of colored squares ( boxes ) that are displayed on the screen . according to the guidelines , by touching boxes and using a process of elimination ,
token in each of boxes and use them to fill up an empty column on the right hand side of the screen .
thus it seems that in the next item , searches should be limited to boxes that contain blue signs .
this process goes on until all blue signs of the boxes are discovered on the screen .
when the trial ends up , a new one begins ( with new color and position different from previous trials ) .
this test consists of 4 experimental trials and every trial has 3 boxes for search ( the first 4 trials will not be scored ) , then test continues with 4 , 6 , and 8 boxes .
the variables used in swm test include errors ( between - group , within - group , and double errors ) , strategy , and latency ( time from when the task is presented until the participant s first touch for opening the box ) ( 27 ) . in this test ,
when a subject touches a box that blue signs have already been found in , errors ( between - group ) are recorded
. within - group errors include the number of errors occurring within a search , for example , the frequency of selecting a box that had been found empty in previous searches , ( frequency of re - selection the empty box in a trial ) .
double errors are calculated when the participant makes an error ( re - selection of an empty box ) that can simultaneously fall within group error categories .
owen et al . ( 30 ) have proposed an effective strategy for accomplishing this task .
to start , a predetermined sequence of boxes marked with a blue sign were found to start and when it comes back , the new scouring is to begin .
estimated use of this strategy ( strategic points ) is obtained from the total number of times that participants seek a new one with 6 and 8 boxes .
the high score indicates a poor use of these strategies and a low score indicates an efficient use .
spatial span assesses working memory capacity , which is a visuospatial analogue of the digit span test .
this test measures the ability to remember the location and order of a set of visual stimuli ( white squares ) displayed on the screen .
the number of boxes is increased from 2 at the start of the test to 9 at the end , and sequence and color are changing through the test .
the test is stopped when the participant fails in all 3 trials of a stage .
time span is defined as the highest level that the subject can remember in a trial .
this measurement requires both visual and spatial components representing the ability to store data temporarily or online in order to plan more operations in the future .
this test has 5 variables span length , mean time to first response ( span length 2 ) , mean time to last response ( span length 2 ) , total errors , and total usage errors ( 30 , 31 ) .
, the participant should press the arrow that displayed on the screen ( according to the arrow s left or right direction , the subject should press the corresponding button ) .
this test consists of two sections : in the first one , the participant is introduced to press the left hand button when he sees a left - pointing arrow , and right hand button when seeing a right - pointing arrow .
there is one block of 16 trials for the subject to practice this . in the second section ,
the participant is told to continue pressing buttons when they see the arrows , as before , but , if they hear an auditory signal ( a beep ) , they should withhold their response and not press the button .
this part consists of 4 blocks each containing 16 trials ( total trials : 64 ) .
the variables of sst include 5 items including direction errors on stop and go trials , proportion of successful stops , median correct reaction time on go trials , stop signal delay , and stop signal rt ( 31 ) .
this scale was developed by young , biggs , ziegler , and meyer ( 32 ) for mania evaluation .
this measure rates symptoms of bipolar disorder in mania episode and consists of 9 items .
the scoring scale is based on severity of symptoms ( total score : 60 ) .
there was a high correlation between scores of two independent clinicians on both the total score ( 0.93 ) and the individual item scores ( 0.66 to 0.92 ) ( 32 ) . reliability and validity of this scale were acceptable in an iranian sample ( isfahan province ) ( 33 ) . in this study ,
concordant validity of ymrs with the world health organization world mental health composite international diagnostic interview ( who wmh - cidi ) was 0.87 .
discriminatory analysis results indicated 17.14 and the optimal cut - off point with 98.4% sensitivity and 98.4% specificity .
ymrs ( young mania rating scale ) is a valid instrument with acceptable sensitivity and specificity which can be applied in both clinical and research settings .
its test - retest reliability has been reported between 0.48 to 0.86 and a mean of 0.86 ( 34 ) .
internal consistency of bdi - ii was estimated to be 0.73 - 0.93 and the correlation between parallel forms was 0.89 .
concurrent validity of the questionnaire with the hamilton rating scale for depression ( hrsd ) and depression subscale of scl-90 has been 0.71 and 0.89 , respectively ( 34 ) . in a study by ghassemzadeh et al . (
35 ) on a persian version of bdi - ii , the test had high internal consistency ( cronbach  = 0.87 ) and acceptable test - retest reliability ( r = 0.74 ) .
this questionnaire consists of 21 multiple choice items ( scoring from 0 to 3 ) , which assesses the severity of anxiety .
three items relate to anxious mood , 3 ones assess specific phobias and other questions evaluate autonomous hyperactivity symptoms and tension .
beck et al . ( 36 ) have reported the internal consistency of this scale as 0.93 and its test - retest reliability as 0.75 .
this questionnaire was validated in iran by kaviani and mousavi ( 37 ) . in their study ,
internal consistency measured by cronbach  was 0.92 ; test - retest reliability was 0.83 and within class validity was 0.83 .
independent t - test was applied to assess differences between means considering p < 0.05 significant level .
in this study , 30 patients ( 15 females , 15 males ) and 30 healthy controls ( 15 females , 15 males ) , were evaluated .
the two groups were matched up to age ( mean  sd of patients , 32.6 7.85 years ; the control group 32.43  7.64 years ) and had no significant differences .
there were no significant differences between the two groups in terms of degree of education ( p <
0.05 , df = 58 , t = -0.294 ) ( number of patients in primary - secondary school level were 7 ( 23.3% ) , and in control group was 5 ( 16.7% ) ; in the second category , high school / diploma level , there were 12 patients ( 40% ) , and 15 controls ( 50% ) ; in diploma / ba level , 9 patients ( 30% ) , and 7 controls ( 23.3% ) , and in the last category , postgraduates ( ma and ph.d . ) , there were 2 people ( 6.7% ) for patients group , and 3 ones for control group ( 10% ) ) .
participants scores regarding bai were not significantly different ( p  0.05 , df = 58 , t = -0.202 ) .
there were also no significant differences in bdi - ii scores ( p > 0.05 , df = 58 , t = 2.84 ) , and the mean score on ymrs was 7 in patients groups .
table 1 presents the results of the sst test . regarding direct errors on stop and go trails ,
bipolar group scored significantly higher than controls ( p  0.05 , t = 3.08 ) and the proportion of successful stops in the bipolar group was significantly lower than the control group ( p  0.05 , t = -2.02 ) .
stop signal reaction time in bipolar group was significantly greater than the control group ( p  0.05 , t = 4.14 ) .
median correct reaction time on go trails was not significant between the two groups ( p  0.05 , t = 1.16 ) .
the delay between the two groups was not significant on stop signal delay ( p  0.05 , t = -1.13 ) .
bipolar group got lower scores than the non - clinical group , and this difference was significant ( p  0.05 , t = -3.89 ) .
the mean latency to first response in the bipolar group was higher than the control group , and the difference was significant ( p  0.05 , t = 3.40 ) and the mean response latency in the last item was also significantly greater in bipolar group ( p  0.05 , t = 3.88 ) .
as shown in table 2 , the mean of total errors in bipolar group is higher than the control group , but this difference was not significant ( p > 0.05 , t = -1.14 ) and the total usage errors was similar between the two groups ( p  0.05 , t = 0.291 ) .
. the total number of between - errors was significantly higher in bipolar group ( p  0.05 , t = 3.98 ) .
between - group errors in 4 , 6 , and 8 boxes stages were significantly higher in bipolar group compared to the control group ( p  0.05 , t = 2.25 ; p  0.05 , t = 3.30 ; and p  0.05 , t = 3.76 , respectively ) .
strategies used in clinical and non - clinical groups were significantly different ( p  0.05 , t = 2.33 ) .
the total error was greater in bipolar group compared to the control group ( p  0.05 , t = 3.76 ) . in 4 boxes step , there was no significant difference in total errors between the two groups ( p > 0.05 , t = 1.91 ) , but total errors in 6 and 8 boxes levels were higher in bipolar group compared to the control group ( p  0.05 , t = 3.24 ; p  0.05 , t = 3.06 , respectively ) . in double - error and within - group
in this study , the performance of working memory and response inhibition of bipolar patients were assessed during remission phase of mania symptoms .
sst results showed that the direction errors in start - stop trials were higher in bipolar group ; and in successful stop ratio , the patients were less successful than the controls .
in addition , the stop reaction time of bipolar group was greater than the control group , indicating that people with bipolar disorder have more errors in sst even after remission of acute mania symptoms .
the results also showed that the time between moving and stopping , considered as response inhibition reaction time ( ssrt ) , was higher in patients than controls .
these results are consistent with the findings of a meta - analysis study done by hajek ( 38 ) .
this meta - analysis included 30 studies , consisting of 635 patients and 677 controls .
findings of this study showed that the patients performance during periods of normal mood ( 228 patients and 277 controls ) was different from healthy controls , also the accuracy level in bipolar group in doing gng test , ssrt , and stroop attention test was weaker than control group during periods of normal mood .
there were similar deficiencies in not paying attention to stroop interferes , and stop signal reaction time ( ssrt ) was significantly different from matched control group .
the patient group had a lower precision and needed more time to inhibit responses . in this study ,
the involved brain areas were also examined by the functional magnetic resonance imaging ( fmri ) .
furthermore , the study of gruber ( 39 ) compared 30 patients suffering from major depression , 17 patients with manic bipolar disorder , and 22 patients with depressive bipolar disorder by several neurocognitive tests ( memory , attention , executive function , and sst ) .
evaluations were done at admission and 7 weeks after discharge ( in recovery period ) . in the first evaluation , manic patients had lower performance in response inhibition reaction time ( sst ) compared to depressive bipolar patients ( ef = 0.75 ) .
although all three groups showed significant improvement after the follow - up period , deficiency in some domains ( especially executive function ) remained constant .
in addition patients with mania had weaker results in inhibition of start responses than patients with major depression ( ef = 0.87 ) and also had poorer performance compared to depressed bipolar patients ( ef = 0.58 ) .
they also had slower reaction time than patients with bipolar depression at the start of the responses ( ef = 0.55 ) .
in their study , two groups of bipolar patients ( 15 ones during manic episode , and 18 patients during normal mood period ) , were compared to 18 healthy controls using object alternation task .
patients during both periods of mania and normal mood showed greater errors in response inhibition compared to the control group .
other researches ( 41 , 42 ) have confirmed deficits in response inhibition during periods of normal mood in patients with bipolar disorder .
there are few studies inconsistent with previous ones ( 43 ) . in this study , 20 patients with bipolar disorder during period of normal mood were compared to 20 controls in response inhibition test ( gng ) ; they were also examined by fmri during this test .
results showed that performance was similar in both groups , while the activity pattern of involved brain areas in response inhibition was different . on the other hand , both the meta - analysis studies by robinson et al .
( 12 ) that examined the patients during periods of normal mood and bora ( 44 ) that examined the close relatives of bipolar patients , suggested that response inhibition was the most prominent factor in the phenotype of bipolar disorder .
this finding is supported by other researches ; patients who are at risk of bipolar disorder show structural changes in areas associated with inhibition ( 38 ) . in conclusion
, it seems that enough evidence supports the idea that response inhibition deficit is an independent phenomenon existing beyond pathological mood episodes in patients with bipolar disorder .
the results of the second hypothesis , in swm test , showed more within - group errors in bipolar patient . in the strategies employed index , there was also significant difference between the two groups , in other words , bipolar patients in normal mood period had more errors on swm test .
( 45 ) . in their research 63 bipolar patients during normal mood period ( 27.3 months on average )
results showed that patients had more within - group errors compared to healthy group in swm , but in strategies employed by the two groups there was not any significant difference , which contradicts with our finding regarding strategies .
in addition , sweeney et al . ( 46 ) using cantab , compared 58 patients with major depression , 21 bipolar patients in depressive phase , 14 ones in mania or mixed episodes , to 51 normal individuals .
patients in mania or mixed episodes had lower performance compared to depressed patients and healthy controls .
also , in the employed strategies , there were significant differences between groups ; patients in manic or mixed phase had the least stability compared to those in the control group or depressed patients .
the third part of our findings regarding ssp test indicated that the span length of clinical group was significantly lower compared to the healthy group .
a significant difference existed in the meantime to first response and meantime to last response delays between the two groups , so that patients needed more time to do their first and last touches .
( 46 ) that bipolar patients in normal mood period had significantly weaker performance in ssp test compared to the control group .
our findings in this section are also compatible with the findings of dittmann et al .
( 15 ) , who examined 65 patients with bipolar disorder type i , 38 patients with bipolar disorder type ii ( both during the period of normal mood ) , and 38 healthy controls using a brief neuropsychological battery .
results indicated that bipolar patients had poorer performance in some items , such as working memory ( measured by the wechsler memory subscale ) compared to the control group .
finally , it was in agreement with other studies confirmed impaired cognitive functions during periods of normal mood in patients with bipolar disorder ( 23 ) , such as cavanagh 's study ( 23 ) , which assessed memory and verbal learning in patients with bipolar disorder in euthmic phase compared to normal group .
findings also revealed negative correlation between frequency of mania episodes and memory function ( delayed recognition domain ) .  
the second limitation is the possible interference of sub - symptoms in cognitive functioning of the patients and the third one is controlling the effect of medications .
most of our patients were on medications including mood stabilizers , antipsychotics , and anxiolytics .
early evidence relating positive effects of mood stabilizers on neurocognitive functioning of bipolar patients ( 47 ) and at the same time some negative effects of antipsychotics on neuropsychological functioning in bipolar patients ( 48 , 49 ) make it hard to draw conclusion about medication effects .
we suggest that further researches with longitudinal designs and using homogenous patients based on their medication regimes can shed light on some of these limitations .
we also suggest that future studies should do more with these confounding factors . in conclusion
, current research suggests that bipolar patients had some inabilities in working memory ability and need more time to inhibit their responses compared to the control group .
these findings have some clinical implications for practitioners such as paying more attention to cognitive symptoms that seems to be impaired even during remission .
also they would be better to consider neuropsychological remediation in their bipolar patients treatment protocols .  
future studies should answer other remaining questions such as what cognitive function in which type of bipolar disorder is stable or transient , and how much these stable cognitive dysfunctions take part in patients specific psychosocial areas of functioning .
also they should clearly respond to questions regarding severity of the illness , and specific clinical features like presence of psychosis , substance abuse , and so on .
 background : several cognitive domains , including attention , memory , and executive functions are impaired in bipolar disorder.objectives:this study aimed to investigate two executive functions ( working memory and response inhibition ) in patients with bipolar i disorder during remission of the symptoms.patients and methods : in this case - control design , 30 bipolar i patients ( 18 to 45 years old ) were matched with 30 ones in the control group in terms of age , gender , and education . 
 the patients were selected from roozbeh psychiatric hospital ( a hospital affiliated to tehran university of medical sciences ) from may to october 2013 . 
 they were evaluated and contrasted using working memory ( spatial span and spatial working memory ( ssp and swm ) ) and response inhibition ( stop signal task ( sst ) ) tests.results:we used independent t - tests for comparing and contrasting 2 groups on total and sub - scales scores of these 3 tests . in terms of swm test there was a significant difference in between - group error between the two groups ( p = 0.05 ) ; there was also a meaningful difference between the strategies used by two groups ( p = 0.05 ) . 
 in ssp test , a significant difference appeared between averages of span length of the two groups . in the first and last item delays 
 , there was also a clear difference , but the total error index was not noticeably different . 
 in sst test , the direction error indicator in start - stop trials indicated a major difference , while in successful stops ratio , the case group had a lower ratio . 
 in addition , reaction time to stop signs in bipolar group was meaningfully lower than the control group.conclusion:in conclusion , even during remission phase , executive dysfunction is detectable at least in some areas in patients with bipolar disorder . 
1. Background
2. Objectives
3. Patients and Methods
3.1. Measures
3.2. Spatial Working Memory 
3.3. Spatial Span 
3.4. Stop Signal Task
3.5. Young Mania Rating Scale 
3.6. Beck Depression Inventory-II
3.7. Beck Anxiety Inventory 
4. Results
5. Discussion