- Top of page
- PATIENTS AND METHODS
- CONCLUSIONS AND RECOMMENDATIONS
- Supporting Information
Depression is a common comorbid condition in Parkinson's disease (PD) and a major contributor to poor quality of life and disability. However, depression can be difficult to assess in patients with PD due to overlapping symptoms and difficulties in the assessment of depression in cognitively impaired patients. As several rating scales have been used to assess depression in PD (dPD), the Movement Disorder Society commissioned a task force to assess their clinimetric properties and make clinical recommendations regarding their use. A systematic literature review was conducted to explore the use of depression scales in PD and determine which scales should be selected for this review. The scales reviewed were the Beck Depression Inventory (BDI), Hamilton Depression Scale (Ham-D), Hospital Anxiety and Depression Scale (HADS), Zung Self-Rating Depression Scale (SDS), Geriatric Depression Scale (GDS), Montgomery-Asberg Depression Rating Scale (MADRS), Unified Parkinson's Disease Rating Scale (UPDRS) Part I, Cornell Scale for the Assessment of Depression in Dementia (CSDD), and the Center for Epidemiologic Studies Depression Scale (CES-D). Seven clinical researchers with clinical and research experience in the assessment of dPD were assigned to review the scales using a structured format. The most appropriate scale is dependent on the clinical or research goal. However, observer-rated scales are preferred if the study or clinical situation permits. For screening purposes, the HAM-D, BDI, HADS, MADRS, and GDS are valid in dPD. The CES-D and CSDD are alternative instruments that need validation in dPD. For measurement of severity of depressive symptoms, the Ham-D, MADRS, BDI, and SDS scales are recommended. Further studies are needed to validate the CSDD, which could be particularly useful for the assessment of severity of dPD in patients with comorbid dementia. To account for overlapping motor and nonmotor symptoms of depression, adjusted instrument cutoff scores may be needed for dPD, and scales to assess severity of motor symptoms (e.g., UPDRS) should also be included to help adjust for confounding factors. The HADS and the GDS include limited motor symptom assessment and may, therefore, be most useful in rating depression severity across a range of PD severity; however, these scales appear insensitive in severe depression. The complex and time-consuming task of developing a new scale to measure depression specifically for patients with PD is currently not warranted. © 2007 Movement Disorder Society
Depressive symptoms commonly occur in Parkinson's disease (PD), affecting approximately 40% of patients in cross-sectional studies.1–3 Depressive symptoms have also been recognized to be a major determinant of health-related quality of life in PD, and can affect functional ability, cognitive function, and caregiver quality of life.4–6 It is, therefore, important to recognize and assess depressive symptoms in patients with PD adequately. The gold standard for the diagnosis of depressive disorder at present are the criteria of the Diagnostic and Statistical Manual, Fourth Edition (DSM-IV), of the American Psychiatric Association. However, in clinical practice and research studies, particularly in epidemiological studies, surveys, and treatment trials measuring severity of depressive symptoms, use of DSM-IV criteria often is not feasible or useful. Several rating scales for screening and/or assessment of severity of depression are available and have been used widely to assess depression in patients with and without PD. However, there are several methodological difficulties in assessing depressive symptoms in PD, and it is unclear which scales are suitable for the assessment of depression in this patient group. The Movement Disorder Society (MDS) Task Force on Rating Scales for Parkinson's Disease therefore commissioned a critique of existing scales as applied to Parkinson's disease and to place them in a clinical and clinimetric context, similar to MDS reviews of the Unified Parkinson's Disease Rating Scale (UPDRS)7 and Hoehn & Yahr staging system.8 The purpose of this effort was the evaluation of all commonly used or appropriate rating scales for depression in PD (dPD) and to make recommendations on the utilization of specific scales and their need for modifications or replacement in this population.
The DSM-IV criteria for depressive disorder are the current gold standard against which such scales are compared. However, the use of these criteria (or other criteria such as the those of the International Classification of Diseases [ICD-10]) in PD has shortfalls, and recommendations have been made to revise the DSM-IV criteria for depressive disorder when applied to PD to overcome these methodological difficulties.9 Although a discussion of the validity of these criteria for depression in patients with PD is not the subject of this manuscript, these problems and their impact on the use of scales to assess of presence and severity of depression in patients with PD are recognized and discussed.
CONCLUSIONS AND RECOMMENDATIONS
- Top of page
- PATIENTS AND METHODS
- CONCLUSIONS AND RECOMMENDATIONS
- Supporting Information
All reviewed scales have some utility in the assessment of dPD. Apart from the UPDRS Part I (which is merely a screening instrument in the context of overall assessment of PD symptoms), they are useful in assessing depressive symptoms in PD. The BDI and Ham-D have been validated and widely used in patients with PD, whereas there are few data available on other scales, particularly the CES-D and CSDD. Further validation studies are required before their use can be recommended in PD. Overall, observer-rated scales (e.g., HAM-D and MADRS) have better psychometric properties than self-rated scales, and observer-rated scales should, therefore, be preferred if the study or clinical situation permits.
Available depression scales serve diverse purposes (e.g., screening instruments vs. instruments used to measure severity and to follow symptoms over time). Different uses require that different scale properties be taken into account and that adaptations of cutoff scores are made as needed (depending on whether sensitivity, specificity, PPV, or NPV are important to the aims of the study). Recommendations have been made above for the appropriate use of each scale. For screening purposes, the HAM-D, BDI, HADS, MADRS, and GDS appear to be useful instruments. The CES-D and CSDD are promising alternatives from a theoretical point of view and should be studied further. The new UPDRS Part I is likely to provide a crude screening instrument for presence of depression, anxiety, apathy, and other target behaviors within the assessment of the spectrum of symptoms of PD. For measurement of severity of depressive symptoms observer-rated scales such as the Ham-D and MADRS as well as the BDI and SDS self-rating scales are more useful and valid, and the CSDD should be studied further.
The diagnosis of depression should not be solely made on the basis of a score on a rating scale. A cutoff score on these instruments cannot comprehensively capture the range of depressive disorders in PD; high scores can occur when somatic symptoms are endorsed even without the two core symptoms of depression (i.e., sad mood and loss of interest or pleasure); low scores can occur despite serious depressive symptoms when somatic or vegetative problems are absent. For this reason, the gold standard for establishing the diagnosis of depression remains a (semi)structured interview using DSM-IV criteria or its equivalent future diagnostic adaptation.
Insufficient evidence is available to recommend the best depression rating scales for PD patients with dementia. Current evidence suggests that the MADRS, GDS, and CSDD may be useful, but further studies are required.
Patients may perceive their own condition differently in an off than during an on period.181Off periods may be associated with severe psychiatric symptoms, including depression, anxiety, and delusions,181, 182 which usually improve together with motor symptoms and are, therefore, typically short-lived. As the reviewed scales are designed to assess the preceding 1 or 2 weeks and as these off periods are also not considered the same as untreated PD and may represent rebound worsening after the beneficial effect of levodopa has worn off,183 we therefore recommend, in line with common practice, that patients with motor fluctuations be assessed for depression during on periods. The scales are therefore also not suitable to specifically assess fluctuating depressive symptoms during off periods versus on periods in the same way that motor symptoms or dyskinesia can be monitored.
All depression scales include items that assess symptoms with overlap between depression, parkinsonism, cognitive impairment, and apathy (see Table 1), particularly the Ham-D and SDS, and to a lesser degree MADRS and BDI. The scale with one of the highest number of items assessing overlapping symptoms, the HAM-D, has the best psychometric properties compared to DSM-IV criteria at recommended adjusted cutoffs. For most studies, instruments that have been demonstrated to have good psychometric properties are recommended above those with poorer validity or reliability or those not validated in dPD. Appropriately adjusted cutoff scores for patients with PD should be chosen and overlapping symptom areas should be assessed in parallel with a primary PD scale like the UPDRS motor scale. This twofold assessment could allow for adjustment of confounding factors in the assessment of depression. The HADS and GDS lack many overlapping items and may, therefore, be useful in the comparison of patients with different disease stages and could also be used to monitor change in depression even in the context of changes in underlying Parkinsonism. They have limited content validity and appear insensitive at the severe end of the depression severity spectrum. As such, they may be useful candidates for studies of mild or mild–moderate depressive symptoms, the most commonly encountered problem in cross-sectional cases of dPD. They would, however, be less useful to assess moderate to severe depression.
In line with the NINDS recommendations9 use of “loss of pleasure” (reflecting anhedonia) may be more specific to depression than loss of interest, which, as a symptom of apathy, may occur in the absence of depression, but this needs to be researched further.
The following unresolved issues require further research:
More studies are needed on the sensitivity, specificity, and positive and negative predictive values of each scale for major depressive disorder in PD, in particular the CSDD scale and the CES-D.
The assessment of concurrent validity of depression scales is typically made in comparison to DSM-IV criteria of major depression. The criteria for assessment of depressive disorder of dPD are undergoing changes,9 and the validity of depression rating scales using these assessment criteria will need to be established.
The inclusion of somatic symptoms in depression scales theoretically leads to falsely inflated depression scores in patients with PD and may influence the results of treatment trials of depression in PD (e.g., with antiparkinsonian medication). This needs to investigated in clinical trials.
In general, the observer should score answers on the scales using an inclusive approach, and patients should be instructed not to attribute their symptoms to either PD or depression when scoring self-rated scales. An exclusive approach may lead to an underestimation of depression severity. However, some scales require judgment, such as the CSDD and to a lesser degree other observer-rated scales such as the MADRS and Ham-D, and may be conducive to using a more etiological approach. Whilst this should be investigated further, in the absence of evidence for advantages of exclusive or etiological approach, the task force advises to follow an inclusive approach.
The evaluated instruments were not designed or are used to identify minor or subsyndromal depression, and do not reflect the diversity of mood disorders seen in PD, including recurrent brief depressive disorder or dysthymia. Thus, further characterization of other types of dPD is required, and cutoffs must be adapted to the purpose of the study and a time frame specified to include more diverse depressive disorders in PD rather than merely using a cutoff for major depression.
Insufficient evidence is currently available on score improvements that represent remission of dPD.
The ability of scales to measure anxiety, anhedonia, or apathy when they occur outside the context of depression needs to be assessed separately.
Further studies are needed on impact of age, cognitive impairment, apathy, and cultural differences on the validity of the depression scales.
The minimal clinically important change and the minimal clinically important difference has been evaluated for only a few of the evaluated scales.110
In this review, we did not assess multidimensional scales, which assess depression as part of a wider assessment. However, these scales, such as the POMS or the NPI, may be useful in some circumstances and require validation before their use can be recommended.
The role of the caregiver in reporting symptoms of depression should be operationalized, particularly on scales such as the CSDD, which assess dPD with comorbid dementia.
The use of scales to measure present state of mood (e.g., for the measurement of short-term mood fluctuations), which requires a change of time scales, needs to be validated before it can be recommended.
Whilst the assessment of dPD with the reviewed scales has many shortcomings, the task force committee agreed that many of the same problems will be encountered when developing a new depression scale for PD. Therefore, at present, the task force does not recommend the development of new scales, but rather advises to better study existing scales. Development of a special depression scale in PD is only useful and feasible if some basic conceptual issues have been agreed upon. Moreover, the possibility of comparing depressive symptoms in PD with those in other (neuro-)psychiatric disorders may have additional advantages over the development of a range of disease-specific depression scales for a large number of disorders, as the issues raised here are not specific to PD.
Drs. Schrag, Barone, Brown, Leentjens, McDonald, Starkstein, and Weintraub are members of the Depression Scale Task Force. Drs. Poewe, Rascol, Sampaio, and Stebbins are members of the Rating Scales Task Force Steering Committee. Dr. Schrag is the chairperson of the Depression Task Force. Dr. Goetz is Chairperson of the Rating Scales Task Force. Critques of scales are presented in more detail in the Appendix that is available on the Movement Disorders Journal website at http://www.interscience.wiley.com/jpages/0885-3185/suppmat.