Quality of life (QoL) is a useful endpoint in the study of multiple sclerosis (MS) not only as a prognostic factor but also as a quality marker of the health care provided. QoL in MS was found to be negatively affected by cognitive impairment [
One hundred consecutive MS outpatients, 36 males and 64 females, took part in this study. All patients were diagnosed according to international diagnostic criteria [
The clinical evaluation included a formal neurological examination, QoL assessment, perceived cognitive impairment evaluation, and assessment of depression, as a part of a thorough medical examination which included assessment of disability by using the Expanded Disability Status Scale (EDSS). The self-reported questionnaires were filled by the MS patients, who received help from the researcher when necessary. The researchers were neurology registrars, who were under the supervision of a consultant neurologist. The assessments were performed in the outpatient clinic, in a quite office which was available for this study purposes.
The Expanded Disability Status Scale (EDSS) [
The patients were asked to complete the Short-Form-36 Health Survey (SF-36) [
Patients were asked to complete the Perceived Deficits Questionnaire (PDQ) which is a self-report disease-specific questionnaire that measures the patients’ perceived degree of cognitive impairment [
Patients were asked to complete the depression subscale of the Mental Health Inventory (MHI), that is, a self-reported questionnaire for assessing the level of depression [
After descriptive statistics and correlation analysis, univariate and multivariate linear regression was conducted to determine the best linear combination of age, gender, education, EDSS, depression, attention/concentration, retrospective memory, prospective memory, and planning/organization, for predicting quality of life scores in each SF-36 subscale. All statistical procedures were performed using the SPSS Statistics version 17.0 (SPSS Inc., Chicago, Ill.).
Characteristics of the total sample of 64 female and 36 male patients with MS that fulfilled the inclusion criteria therefore included in the analysis are presented in Table
Characteristics of MS patients (
Characteristics | Total sample | Males ( |
Females ( |
|
---|---|---|---|---|
Age, years | 40.5 ± 10.3 | 40.9 ± 12.1 | 40.2 ± 9.2 | NS |
Education level (A/B/C) % | 19/57/24 | 25/56/19 | 16/58/26 | — |
EDSS | 3.6 ± 1.9 | 3.9 ± 2.2 | 3.4 ± 1.7 | NS |
MHI-depression | 69.0 ± 21.0 | 71.7 ± 21.2 | 67.5 ± 20.9 | NS |
PDQ-attention/concentration | 4.8 ± 4.0 | 4 ± 3.4 | 5.2 ± 4.3 | NS |
PDQ-retrospective memory | 3.9 ± 4.3 | 3.2 ± 3.9 | 4.3 ± 4.5 | NS |
PDQ-prospective memory | 2.8 ± 3.4 | 2.3 ± 2.9 | 3.1 ± 3.6 | NS |
PDQ-planning/organization | 3.1 ± 3.8 | 2.4 ± 3.3 | 3.4 ± 4.0 | NS |
SF-36 physical functioning | 66.0 ± 36.2 | 65.7 ± 42.1 | 66.1 ± 32.7 | NS |
SF-36 role physical | 69.0 ± 42.4 | 72.2 ± 40.9 | 67.2 ± 43.4 | NS |
SF-36 general health | 60.7 ± 20.1 | 63.9 ± 20.9 | 58.9 ± 19.6 | NS |
SF-36 vitality | 55.0 ± 23.0 | 60.6 ± 23.8 | 51.9 ± 22.0 | NS |
SF-36 social functioning | 72.4 ± 29.0 | 74.0 ± 30.1 | 71.5 ± 28.5 | NS |
SF-36 role emotional | 75.0 ± 40.6 | 76.0 ± 40.3 | 74.5 ± 41.0 | NS |
SF-36 mental health | 58.7 ± 17.5 | 62.9 ± 17.6 | 56.4 ± 17.2 | NS |
Unless specified otherwise, values are presented as means ± SD. Significance level or alpha (
A correlation analysis using Pearson’s
Scatter plot showing the relationship between depression and perceived impairment of planning/organization ability in population of patients with MS.
In Table
Simultaneous multiple regression analysis summary for age, education level, EDSS, depression, attention/concentration, retrospective memory, prospective memory, planning/organization, and predicting SF-36 QoL scales. Only significant factors appear in columns.
MHI depression | PDQ-retrospective memory | PDQ-planning/organization | |
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Physical functioning |
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Role physical |
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General health |
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|
|
Vitality |
|
|
|
Social functioning |
|
|
|
Role emotional |
|
|
|
Mental health |
|
EDSS, Expanded Disability Status Scale; MHI, Mental Health Inventory; SF-36, Short Form 36-item Health Survey; QoL, quality of life; PDQ, Perceived Deficits Questionnaire.
Our data showed moderate correlations between depression and perceived cognitive impairment scales. Other studies also found a relationship between cognitive impairment and depression in MS population [
Our analysis showed that specific perceived cognitive impairments affect QoL independently of depression. Specifically, perceived impairment of planning/organization affects general health, vitality, social functioning, and role emotional QoL subscales independently of depression. In addition, perceived impairment of the retrospective memory affects general health and vitality subscales independently of depression. Interestingly, perceived attention/concentration dysfunction, as well as perceived prospective memory dysfunction, did not independently predict any QoL scores in our multinomial regression models. It seems that impairment in planning/organization and/or retrospective memory affects and decreases the QoL scales to a larger degree than do impairment of prospective memory and/or attention concentration.
Other studies also found self-reported cognitive impairment to correlate with impaired QoL [
Depression is a well-known factor negatively affecting QoL and this is also confirmed in our data. We found evidence that depression predicts decreased QoL in the QoL scales of SF-36. Depression is a well-established QoL determinator not only in MS but also in many other medical conditions. Other studies have also demonstrated that depression affects QoL in MS population [
The strength of this study is that by involving a relatively large population of MS outpatients we explored associations between perceived cognitive impairment and QoL. To the knowledge of the authors this is the first evidence of this, and more extensive investigation is needed in order to delineate possible etiological factors as neurological and psychosocial correlates. A limitation of this study is that we did not include an additional objective neuropsychological assessment in order to explore the effects of objective cognitive decline on patients QoL as well as to compare the size of correlations between subjective and objective impairment in the explored areas of cognitive function. Even if this was not the point in this study, other authors already explored this area with contradictory results [
Another limitation of this study is its cross-sectional design and the lack of second measurement, something that by definition yields bidirectional results. Cross-sectional design does not make it possible to explore for causal relationships between depression, cognitive impairment, and decline of QoL, despite the moderate correlation coefficients found. A prospective longitudinal design, using a structural equation model analysis, could probably define the unidirectional or bidirectional nature of these relationships.
Some authors suggested a common effect between depression and perceived cognitive impairment [
Perceived cognitive dysfunctions could be taken into account in the individualized rehabilitation plan in order to maximize rehabilitation’s effectiveness on patients’ QoL. During the rehabilitation process, clinicians should consider the possibility that cognitive testing confirms what the patients perceive regarding organizational skill deficits as well as the possibility that cognitive testing demonstrates that these cognitive abilities are preserved.
Perceived cognitive impairment in patients with MS constitutes a constellation of symptoms that the clinician should take into consideration. This could be a secondary sign of hidden depression but could also be an independent cognitive factor that is negatively affecting patients’ quality of life. Both phenomena should be taken into account in the treatment process as well as in the design of rehabilitation programs.
We examine effects of perceived cognitive impairment in QoL in a clinical sample of outpatients with MS. We also examine if these effects are independent of MS severity and depression. Perceived planning/organization dysfunction as well as perceived retrospective memory dysfunction independently predict QoL in MS. Perceived attention/concentration and prospective memory dysfunctions do not. Both of these perceived cognitive dysfunctions could be taken into account in the individualized rehabilitation plan in order to maximize rehabilitation’s effectiveness on patients’ QoL.
The authors declare that there is no conflict of interests.
Lampros Samartzis, M.D., contributed to the design and conceptualization of the study, analysis, and interpretation of the data, as well as to drafting and revising the paper. Efthymia Gavala, M.D., contributed to the design and conceptualization of the study as well as to drafting and revising the paper. Yiannis Zoukos, M.D. and Ph.D., contributed to the design and conceptualization of the study and interpretation of the data, as well as to revising the paper. Achileas Aspiotis, M.D., contributed to the design and conceptualization of the study, as well as to the interpretation of the data. Thomas Thomaides, M.D. and Ph.D., contributed to the design and conceptualization of the study and interpretation of the data, as well as to revising the paper.