subjective cognitive complaints ( scc ) are quite prevalent among older adults , with some estimates suggesting that between 25% and 50% of all older adults have self - perceived memory impairment [ 1 , 2 ] . in clinical practice , it is often difficult to assess the veracity and severity of subjective cognitive complaints , primarily because such complaints vary widely from individual to individual . as a result
, clinicians and caregivers perhaps do not consider subjective complaints to have the same weight as objective findings .
however , studies have shown that subjective complaints may be valid indicators of current and future cognitive impairment . a recent study by amariglio and colleagues showed that certain subjective complaints , such as  i have trouble finding my way around familiar streets ,  are correlated with impairment in delayed recall , naming , and semantic fluency .
a review conducted by jonker and colleagues showed that memory complaints may be predictive of dementia or alzheimer 's disease onset within two to four years , especially in individuals with a diagnosis of mild cognitive impairment ( mci ) .
subjective cognitive complaints also have clinical implications that are outside the realm of cognitive function . a review by mol and colleagues   found that scc correlated with depression , anxiety [ 4 , 5 ] , and low level of well - being , even in the absence of objective cognitive impairment .
scc and objective cognitive function in older patients with and without major depression and found no changes in objective cognitive function between the two groups , but significantly more scc in the depressed group .
scc have also been correlated with decreased functional ability , even when depression is controlled for .
although the direction of causality between many of these variables remains unclear , scc should be considered in a clinical setting because of their associations with objective impairment , dementia , depression , low quality of life , and functional ability .
previous research in the area of scc has largely focused on memory complaints [ 13 , 7 , 8 ] . in the current study , we have broadened the scope of scc in order to examine other areas of cognition that have shown impairment following complaints .
the most common method appears to be a single , dichotomous ,  yes or no  assessment of complaints ( e.g. ,  do you find that you have trouble with your memory ?  ) [ 713 ] , or a combination of similar  yes or no  questions [ 3 , 14 , 15 ] .
furthermore , most of the existing literature on scc examines community - dwelling , healthy , and older populations [ 3 , 7 , 9 , 12 , 16 ] .  
subjective cognitive complaints , in addition to predicting the onset of a neurodegenerative process , may yield important information about areas of impairment , specifically in patients with mild disease .
two such disorders are mild cognitive impairment ( mci ) and its vascular equivalent , vascular mild cognitive impairment ( vamci ) .
differences in functional impairment between individuals with mci and those with vamci , which may be overlooked by objective cognitive testing , may be predicted by an analysis of significance of scc . in the current study , we compared the profile of scc in individuals with a diagnosis of mci to those with vamci using the neuropsychological impairment scale ( nis ) .
the nis is a comprehensive scale - based questionnaire , which may elicit differences in presence and severity of scc between the two groups .
we hypothesized that the severity of subjective cognitive complaints would not differ between the two groups , because objective cognitive functioning is similar .
however , we hypothesized that the specific types of scc might differ between mci and vamci , due to the differing pathologies of these two disorders .
twenty patients with mci and twenty patients with vamci matched on demographic characteristics ( age , education ) were recruited from the memory disorders clinic at st .
patients are referred to the clinic by their primary or secondary care physicians , for assessment and diagnosis of cognitive impairment .
patients typically undergo a standardized history and a standardized cognitive exam as part of the workup .
in addition , routine blood work including tsh , b12 , and rbc folate is done to rule out reversible causes of dementia . as well
, most patients receive structural imaging ( either computed tomography ( ct ) or magnetic resonance imaging ( mri ) ) and in some cases functional imaging ( single photon emission computed tomography ( spect ) ) . for this study , only patients clinically diagnosed with either mci or vamci were recruited .
the diagnostic criteria for mci describe cognitive impairment which is more severe than normal aging but less severe than dementia and typically not associated with serious impairment in everyday functions .
vamci is described as the vascular equivalent of mci , thereby indicating a similar level of objective cognitive performance despite possible differences in mechanism and etiology .
currently , there are no specific neuroimaging or vascular criteria that are necessary for a diagnosis of vamci .
some patients underwent mri scans instead of ct scans as part of their clinical visit .
as we used different imaging modalities we could not compare degree of white matter disease across study subjects in a quantifiable manner .
rather , patients were assigned to the vamci group if scans showed evidence of white matter lesions , lacunar infarcts , and/or moderate to severe microangiopathic change .
cognitive testing and data intake occurred during the patients ' initial visits to the clinic .
follow - up visits to the memory disorders clinic were not considered for this cross - sectional analysis .
subjective cognitive complaints were assessed using the neuropsychological impairment scale ( nis ) [ 20 , 21 ] .
the nis is a questionnaire consisting of 95 complaints , such as  i am forgetful  and  i am easily distracted .
 subjects rated these statements on a five - point likert scale according to applicability and intensity .
when scored , the nis divides complaints into seven domains : critical items ( e.g. , head injury , stroke , and dizziness ) , cognitive efficiency ( e.g. , confusion , mental slowness ) , and attention , memory , frustration tolerance , verbal learning , and academic skills ( e.g. , counting change , learning new tasks ) .
the nis also includes three scores that give a general , comprehensive picture of complaints : the global measure of impairment ( gmi ) score is a simple sum of all domain subscores ; the total items circled ( tic ) score indicates how many complaints are reported ; and the symptom intensity measure ( sim ) score indicates the average intensity of complaints .
the nis also includes three validity checks : defensiveness , inconsistency , and affective disturbance .
thus , the nis can detect if subjects are overly defensive or inconsistent ; and the affective disturbance validity check controls for levels of depression and other emotional disturbances .
the mini - mental state examination ( mmse )   was used to measure cognitive performance from a general perspective .
the bna consists of five subcategories : memory , attention , naming , visuospatial function , and executive function .
functional ability was objectively assessed using the older american resources and services ( oars ) activities of daily living questionnaire .
this questionnaire assesses fourteen activities of daily living ( adls ) : seven basic adls ( eating , dressing and undressing , grooming , walking , getting in and out of bed , bathing , and going to the bathroom ) and seven instrumental adls ( using the telephone , traveling , shopping , preparing meals , doing housework , taking medications , and handling money ) .
subjects were asked about their own ability to perform the above adls ; where possible , informants who knew the subjects well were asked to supplement and verify responses .  
mean scores for each group ( mci and vamci ) were compared via an independent samples t - test .
age , education , and other demographic factors were also compared between the two groups .
the mci and vamci groups were matched on demographic measures such as age , years of education , and hollingshead two - factor index of social position ( table 1 ) .
functional ability , as measured by the oars questionnaire , was also similar between the two groups ( p = 0.919 ) ( table 2 ) .
objective cognition function was measured by the mmse and the bna ( table 2 ) .
mmse scores were similar between the two groups ( p = 0.330 ) , which implies similar levels of general cognitive function .
overall bna scores were also similar between the mci and vamci groups ( p = 0.177 )
. scores from subcategories of the bna were also compared between groups to look for specific areas of cognitive impairment ( table 2 ) .
performance on all subcategories of the bna ( attention , memory , naming , visuospatial function , and executive function ) was similar between mci and vamci groups .
performance on the individual tasks which comprise the above five subcategories was also similar between groups , with the exception of the  explaining proverbs  task ( p = 0.034 ) . on this task , which falls into the subcategory of executive function
, mci subjects averaged a better score than vamci subjects ( 3.15 compared to 2.30 ) . despite similar performance on objective functional and cognitive measures ( oars , mmse , and bna ) ,
the mci and vamci groups achieved markedly different results when subjective cognitive complaints were assessed by the nis . in general ,
vamci subjects had significantly higher scores on the nis than mci subjects ( table 3 ) ; higher scores indicate greater scc .
the nis global measure of impairment ( gmi ) score gives a broad , comprehensive view of complaints .
the vamci group averaged a gmi score of 117.0 , compared to just 79.3 for the mci group ( p = 0.050 ) .
a qualitative analysis of the total items circled ( tic ) scores shows that vamci subjects had a greater number of complaints than mci subjects ( 52.8 compared to 44.2 ) ; however this difference was not statistically significant ( p = 0.136 ) .
the symptom intensity measure ( sim ) scores reveal that vamci subjects ' complaints were greater in severity than those of mci subjects ( 2.0 compared to 1.7 ) ; however , again , this difference was not statistically significant ( p = 0.065 ) .
thus , we can not attribute the difference in gmi scores to just one cause .
rather , it is likely that difference in gmi scores stems from differences in both complaint quantity and complaint severity .
quantitatively , the vamci group had higher scores in all seven domains of the nis ( table 3 ) .
four of these domains yielded differences in scores that were statistically significant : critical items ( p = 0.017 ) , cognitive efficiency ( p = 0.043 ) , memory ( p = 0.046 ) , and verbal learning ( p = 0.027 ) .
the nis also includes three validity checks to test for defensiveness , affective disturbance , and inconsistency . in our sample of subjects
, there was no statistical difference in any of the above variables between the mci and vamci groups ( table 3 ) , confirming that the complaints were valid .
although vamci subjects had qualitatively higher scores on the three validity measures , their scores were not significantly different from those of the mci group .
mci and vamci are clinical conditions that precede the development of neurodegenerative disorders including alzheimer 's disease and vascular dementia , respectively .
apart from differences on neuroimaging there has been very little study of how these two clinical conditions differ in terms of their subjective and objective clinical profiles . taken altogether , our findings from the mmse , bna , oars , and nis show that despite similar levels of functional ability and objective cognitive function , vamci subjects have significantly more scc than mci subjects .
our findings support the existing view of mci and vamci as disorders with similar presentations with regard to objective function , but ultimately different etiologies .
as previously discussed , mci and vamci subjects were matched on age , education , and social status and achieved statistically similar scores on the mmse and bna .
the one component of the bna that differed between the two groups was the  explaining proverbs  task ; however , this seeming disparity may have resulted from differences in cultural background . in our sample of patients from the diverse city of toronto , 17 out of 40 subjects (
unfamiliarity with english proverbs certainly confounded this result and may explain this difference observed on the bna . leaving aside this single anomaly , our findings show that mci and vamci subjects had comparable levels of objective cognitive function .
however , our findings from the nis questionnaire show that vamci subjects had more subjective cognitive complaints than their mci counterparts .
this discrepancy suggests that vamci patients are exhibiting particular cognitive deficits , which are not identified by the bna , or that vamci patients are more sensitive to and aware of mild deficits in these particular areas .
the nature of vamci - specific deficits may be determined from the domains in which vamci patients report greater complaints : critical items , cognitive efficiency , memory , and verbal learning .
the critical items domain references events in a patient 's history that are evident predictors of cognitive difficulty : dizziness , concussion , head trauma , stroke , and so forth .
vamci subjects reported greater complaints in this domain than mci subjects ; this finding may be explained by simply considering the diagnostic criteria of vamci compared to those of mci . as mentioned above , history of clinical stroke can differentiate vamci from mci .
a vamci patient is more likely than an mci patient to have experienced stroke or stroke - like symptoms , so he / she is more likely to have complaints in the critical items domain .
vamci subjects ' greater complaints in the memory , verbal learning , and cognitive efficiency domains may be explained by examining the pathology of vamci , which differs from that of mci upon neuroimaging . a study by vannorsdall et al .
found that white matter hyperintensities in both periventricular and subcortical regions correlated with poorer working memory .
found that deep white matter hyperintensities correlated with decreased performance on verbal fluency tasks , while periventricular hyperintensities were not associated with any particular domain .
white matter lesions have also been correlated with slowed information processing [ 25 , 27 ] .
recent research has demonstrated that this decrease in processing speed may be specific to white matter lesions in the anterior thalamic radiation .  
our analysis may be hampered by the limitations of our cognitive testing methods . in this study , the
mmse and bna may have suffered from ceiling effects , which would have masked any differences in cognitive function between the mci and vamci groups .
however , the advantages of the mmse and bna are numerous and informed our decision to use these tests .
in addition , more sensitive cognitive testing would not have been possible at the study facility , given the amount of time allotted for a clinical visit .
the differences we have found in scc between mci and vamci groups may suggest a need for alternate cognitive testing methods , which , unlike the mmse or bna , would elicit different results between the two groups and would not suffer from ceiling effects .
our study has demonstrated that vamci patients may be exhibiting particular cognitive deficits in memory , verbal learning , and cognitive efficiency , separate from those exhibited by mci patients .
these deficits may be explained by the greater white matter burden in vamci patients , as compared to age - matched mci patients .
further research should be done to elaborate on the nature of vamci - specific deficits , particularly in the domains we have identified in this study .
as well , vamci - specific deficits should be related to neuroimaging findings , in order to associate deficits with particular locations and severities of white matter disease .
finally , tools for more sensitive cognitive testing must be developed , so that we may identify vamci - specific cognitive deficits .
 
 objective . vascular mild cognitive impairment ( vamci ) is differentiated from mild cognitive impairment ( mci ) by the presence of vascular events such as stroke or small vessel disease . 
 typically , mci and vamci patients present with subjective complaints regarding cognition ; however , little is known about the specific nature of these complaints . 
 we aimed to create a profile of subjective cognitive complaints in mci and vamci patients with similar levels of objective cognitive performance . 
 methods . 
 twenty mci and twenty vamci patients were recruited from a memory disorders clinic in toronto . 
 subjective cognitive complaints were assessed and categorized using the neuropsychological impairment scale . results . 
 mci and vamci patients achieved similar scores on measures of objective cognitive function ( p > 0.100 ) . 
 however , the vamci group had more subjective complaints than the mci group ( p = 0.050 ) , particularly in the critical items , cognitive efficiency , memory , and verbal learning domains of the neuropsychological impairment scale . conclusions . 
 our findings support the idea that vamci and mci differ in their clinical profiles , independent of neuroimaging . 
 vamci patients have significantly more subjective cognitive complaints and may be exhibiting particular deficits in memory , verbal learning , and cognitive efficiency . 
 our findings promote the need for further research into vamci - specific cognitive deficits . 
1. Introduction
2. Methods
3. Results
4. Discussion