The International Journal of Psychosocial Rehabilitation


Study on the association between severity/recovery of depression and severity/recovery of gross motor retardation

    J Knapen. 1, 2

 E Coppens 1 
 
D Vancampfort 1, 2

P Minquet 1, 2

 A Schueuremans 2

A De Herdt 1

M Probst 1, 2


Faculty of Kinesiology and Rehabilitation Sciences
1.
Katholieke Universiteit Leuven, Tervuursevest 101, 3001 Leuven, Belgium
2. University Psychiatric Centre K.U.Leuven, Campus Kortenberg, Leuvensesteenweg 517, 3070 Kortenberg, Belgium


Citation:
Knapen, J., Coppens, E., Vancampfort, D., Minguet, P., Schueuremans, A.,  De Herdt, A., Probst, M. (2012). Study on the Perceived Exertion during a Graded 
Exercise Test in Patients with Depressive and Anxiety Disorders
 International Journal of Psychosocial Rehabilitation. Vol 16(2) 11-19


Corresponding author:
Jan Knapen
University Psychiatric Centre K.U.Leuven, Campus Kortenberg
Leuvensesteenweg 517
3070 Kortenberg,
Belgium
Mail: jan.knapen@faber.kuleuven.be

Acknowledgements:
The authors thank the patients who participated in the study and staff members of the University Psychiatric Centre Katholieke Universiteit Leuven, Campus Sint-Jozef Kortenberg for their help during data collection.


Abstract
Purpose: To examine the associations between severity/improvement of depression and severity/changes of psychomotor retardation (PR). Previous research on these topics was mainly conducted within the cognitive or fine motor domain of PR. This study focuses on the gross motor retardation.
Method: Twenty-three hospitalized patients performed a six-minute walk test, a plate tapping test and a cycle ergometer test. Total walking distance (TWD), average amount of steps per 50 meter (SFM), time to complete the plate tapping test (PT) and average cycle speed (ACS) were measured. Average walking speed (AWS) was calculated from TWD, average stride length (ASL) estimated from SFM. Severity of depression (IDS) was assessed with the self-rated Inventory of Depressive Symptomatology (IDS-SR). After a treatment period of 8 weeks all tests were repeated as well as the IDS measurement. Differences between T1 and T2 results were calculated.
Results:
IDS, AWS, ACS, PT improved but not ASL. Only AWS and PT scores were significantly correlated with IDS. No relationships were found between improvement in depression and gross motor parameters.
Conclusions: The relationship between recovery of depression and PR does not seem transferable to the gross motor domain of PR (walking, cycling and arm movement). More homogeneous samples are needed in further research.



Introduction
Psychomotor retardation (PR) is an important feature of depression (1). Through the literature, PR is defined as ‘motor slowing’, ‘psychomotor slowing’, ‘psychomotor impairment’, ‘psychomotor disturbance’, ‘motor retardation’, or just ‘slowing’. A description of what exactly these terms imply, is in most articles not given. Some reviews tried to summarize all characteristics of PR (1 - 5), but a clear definition is still absent. The Diagnostic and Statistical Manual for Mental Disorders, 4th edition, text revision (DSM-IV-TR) defines PR in its glossary as ‘a visible generalized slowing of movements and speech’ (6).
 
Psychomotor retardation in depressed patients is considered to be the result of two types of slowing: cognitive and motor (7). Most studies on PR focussed on fine motor movements like drawing or finger-tapping, therefore, how exactly PR manifests itself in gross motor activities like walking, cycling or gross movements of the upper limbs, is less known. The few studies that have investigated gait/walking in depressed patients revealed that compared to controls, depressed patients show a specific, slowed ‘Parkinsonian-like’ (8) gait. Bader and colleagues (9) examined various gait characteristics in 20 moderately to severely depressed inpatients. The results were compared with those of 20 matched healthy controls. The depressed group differed significantly from the control group in terms of step length (shorter) and average walking speed (slower) during a 3-minute walking test. Hergueta and colleagues (10) performed quantitative video-analyses of gait in 26 depressed inpatients and 26 healthy controls. They observed lower heel propulsion velocity and shorter stride length in the depressed group compared to the healthy control group. In another study (11) spatiotemporal gait parameters were measured during over ground walking at self-selected walking speed. Compared to controls, 16 depressed patients showed significantly lower gait velocity, reduced stride length, double limb support and cycle duration. Other studies showed similar results (4, 12). Depressed patients tend to move their upper limbs less frequent and more slowly in comparison with healthy persons. Not many studies were performed on this subject, and they were all observational studies. To the authors’ knowledge, cycling has even never been investigated in the context of PR in depressed patients.

For diagnostic purpose, a fundamental question regarding PR is in which subtype of depression this symptom occurs and in which it doesn’t. Studies showed that the manifestation of PR is highly unlikely in non-melancholic depression and highly probable in the melancholic subtype (1, 4). Research demonstrated that bipolar depressed patients are very likely to have the melancholic subtype with the according psychomotor retardation (13). Moreover, several authors have suggested that PR may represent a marker for bipolarity in patients with MDD (14). Thus, PR is considered a main feature of melancholia. Nonetheless, not all melancholic depressed patients have PR, and sometimes PR has been found present in patients with another subtype of depression (4). This can be partly explained by another possible determinant for the presence of PR within the clinical state of depressed patients, the severity of depression. Schotte and colleagues introduced in 1997 an integrated threshold model (15). According to this model, melancholic symptoms and PR appear above a certain severity of depression. Several other studies have demonstrated that the presence of PR is associated with  severity of depression (1, 4).
 
Not only presence, but also degree of PR and depression severity are thought to be related (1). Most research results on this association were obtained by the use of cognitive or fine motor tasks. In a review concerning visuomotor tasks (16) the authors pointed out the possibility that melancholic depressed patients were slower because they were more depressed. Visuomotor tasks such as copying tasks, the Digit Symbol Substitution Test and the Fitts’ task are frequently used in PR research examining this association. They combine both fine motor (movement time, velocity) and cognitive measures (reaction time). Reaction time and velocity (2, 7) were found to be related to severity of depression. The Salpêtrière Retardation Rating Scale (SRRS), a symptom severity scale specific to psychomotor retardation, includes items related to motility, speech and cognition (18). Research showed positive correlations between this scale and depression severity (1). As regard the gross motor aspect, one study (19) found that more severely depressed patients were more likely to be less active during 24h.
 
Related to the association severity of depression/degree of PR, is the question whether recovery of depression (total or partial) is associated with improvement in psychomotor slowing, or whether PR is an indicator of treatment response in depressed patients. Schrijvers and colleagues (4) summarized previous research results on this topic, concluding that treatment with antidepressants during 3 to 12 weeks resulted in total or partial improvement of psychomotor functioning, mostly due to clinical recovery. A more recent review (5) made similar conclusions. The above-mentioned disbalance between cognitive and motor research and between fine motor research and gross motor research continues to apply within this research topic. In cognitive/fine motor research partial or total recovery of depression was found to be related to recovery of slowed movement time during drawing tasks (20). There is no consensus regarding reaction time (21, 22). However fewer studies were conducted, stronger evidence on this association was found in research focussing on the gross motor domain. In the study of Bader and colleagues (9) patients improved in terms of stride length, maximal walking distance and maximal walking speed after 3 weeks of inpatient treatment and significant symptomatic improvement. In the study of Hergueta and colleagues (10), heel propulsion velocity returned to normal when patients with depression were discharged after 3 weeks of inpatient treatment, however length of stride remained shorter. The study of Lecrubier (8) showed that stride length only significantly improved after 3 months of venlafaxine treatment, where heel propulsion velocity already improved after 2 or 3 weeks. The combined data of these studies reveal the possibility that not all psychomotor retardation improves at the same rate.
 
The aims of the present study were to examine the association between severity of depression and severity of PR, and secondly between (partial) recovery of depression and changes in PR, hereby focussing exclusively on the gross motor aspect. Gross motor disturbance was assessed by average speed of walking and step length during a 6-minute walk test, arm movement speed during the plate tapping test and average cycle speed during a 10-minute submaximal test on a bicycle ergometer. To the authors’ knowledge, the present study is the first to evaluate the association between PR and severity/recovery of depression through cycle speed and speed of upper limbs. As previous mentioned, speed of walking and step length has been the subject of such research before, but these parameters were never measured with the 6-minute walk test (although the 3-minute walk test in the study of Bader was very similar to the 6-minute version). Based on the above-mentioned research results, we hypothesized that severity of depression is positively associated with degree of gross motor disturbance and secondly that (partial) recovery of depression is positively associated with improvement in gross motor functioning. In order to answer these research questions, an 8-week longitudinal study design was set up.
 
Method
Subjects
The depressed patients were recruited from December 2010 until March 2011 from two different treatment units of the University Psychiatric Centre Katholieke Universiteit Leuven, Campus Sint-Jozef Kortenberg in Belgium. All patients who were diagnosed by trained psychiatrists according to the DSM-IV-TR (23) with depressive disorder, bipolar I or II disorder (in the depressed phase), adjustment disorder with depressed mood or adjustment disorder with mixed anxiety and depressed mood and who had observed PR were asked to take part in the study. Patients were excluded if they were agitated or if they had clinically significant co-morbidities likely to affect motor functioning and test performance/results including severe orthopaedic problems, severe cardiopulmonary diseases, neurological diseases, schizophrenia and chronic fatigue syndrome. Patients who were treated with electroconvulsive therapy  were also excluded because this treatment has a greater effect on PR than drug therapy (1). All included patients received a similar multi-dimensional treatment consisting of 3 or 4 psychomotor therapy sessions per week, different forms of psychotherapy and occupational therapy and drug therapy. At time of their inclusion, all patients were using different types of antidepressants: tricyclic antidepressants (TCA’s, n=16), selective serotonin reuptake inhibitors (SSRI’s, n=6), monoamine oxidase inhibitor (MAO, n=1) and lithium (n=1). Twenty patients were treated with with a combination of antidepressant wth antipsychotics and benzodiazepines. This medication was changed as little as possible during the testing period. If major changes in medication use occurred during the test period, those patients were excluded from further testing.
 
Instruments and procedures
In this 8-week longitudinal study, patients were tested twice. T1 refers to the first testing moment; T2 refers to the second series of tests after 8 weeks treatment. During each test moment, patients carried out 3 tasks containing gross motor movements: the Six-Minute Walk Test (6MWT), a 10-minute submaximal test on a bicycle ergometer (CET) and the plate tapping test (PT). They also filled in the self-rated Inventory of Depressive Symptomatology (IDS-SR) so the severity of their depression could be determined.
 
Six-Minute Walk Test
The 6MWT is a well described functional exercise capacity test. This test is used in different rehabilitation settings, mostly to evaluate patients with cardiopulmonary disorders. To conduct the 6MWT in a standardized manner, a practical guideline concerning indications, factors that influence results, interpretation of results and a step-by-step protocol has been set up by the American Thoracic Society (24). For the present study, patients were told to walk a distance as large as possible in 6 minutes. They had to walk up and down a hallway over 25 meters. Total walking distance (TWD, in meters) and the average amount of steps per fifty meters (SFM) were measured. From TWD, average walking speed (AWS, in km/h) could easily be calculated and logged per patient. The average amount of steps per fifty meters is associated with the average step length (ASL). When a patient takes sixty steps over fifty meters, we can say he takes bigger steps then when he would have taken 70 steps over fifty meters. For safety reasons, heart rate and blood pressure were measured just before and after the test (blood pressure meter type OMRON). Before the test, all examinees had to fill in a questionnaire concerning orthopaedic problems that could interfere with their performance.
 
The bicycle ergometer test
The CET was performed on an electronically braked bicycle ergometer (Ergo 2000, Ergo-Fit, The Netherlands). All patients were told to cycle 10 minutes at a self-selected intensity, meaning they were free to choose the workload and cycle speed, as long as it felt comfortable and they would not exert themselves. During the test 4 parameters were obtained: average workload (AW, in Watt), average cycle speed (ACS, in rotations/min). Also the saddle height was measured. For safety reasons, all patients’ heart rates were constantly monitored.
 
Plate Tapping Test
Plate Tapping is a test to assess speed and coordination of upper limb movement. This test is part of the Eurofit Physical Fitness Test Battery (25), originally devised by the Council of Europe for children of school age. In 1995 a similar test battery was published for adults (26). Two discs were placed on a table with their centres 60 cm apart. Examinees were asked to place their non-dominant hand on a rectangle that is placed equidistant between both discs. They had to move their dominant hand back and forth between the discs over the hand in the middle. This was repeated for 25 full cycles (50 taps). Patients were asked to perform the test as quickly as possible. To control for learning bias, the test was performed twice with an interval of 1 minute. Only the faster of the two scores (in seconds) was used for statistical analysis.
 
Severity of depression
Severity of depression was assessed by the Inventory of Depressive Symptomatology Self Report (IDS-SR) total score (27, 28). IDS-SR is a widely used 30-item questionnaire, developed by Rush in 1985, that has to be filled in by the patient. The total score of the questionnaire can vary between 0 and 84. A score between 0 and 13 should be interpreted as not depressed, between 14 and 25 as mildly depressed, between 26 and 38 as moderate, between 39 and 48 as severe, between 49 and 84 as very severe. Patients filled in the Dutch translation of this questionnaire right before the CET. The questionnaire has been shown adequately reliable and valid to rate the severity of depression in patients with mood disorders (27, 28).
 
Test 2
During T2, patients had to fill in the IDS-SR again and the 6MWT test and PT were performed in the same way as T1. However, during CET2, the patients were asked to cycle at approximately the same workload they had chosen themselves during T1. A deviation of 2 Watt was accepted. In this way, both test performances could be easily compared. Besides this adjustment, CET2 was performed in standardized conditions: on the same bicycle, with the saddle at the same height as it was during T1. Because PR can fluctuate during the day (3), patients performed the second tests at approximately the same hour of day as the first tests. In between the two test periods, patients continued to follow their treatment program as described above.
Statistical analysis
 
Statistical analysis was performed using Statistica 9 (29). A two-tailed t-test for dependent samples was used to determine if T1 results differ significantly from T2 results. The relationship between severity of depression (IDS scores) and PR (results on the gross motor functioning tests) and between recovery of depression (ΔIDS) and changes in PR was examined by calculating the Pearson product-moment correlation coefficients. For all analyses, a p-value < 0 .05 was adopted as the level of significance.
 
Results
Subject characteristics
Initially 30 patients took part in the study. Seven of them dropped out due to early discharge from the hospital (n=5) or because they were not willing to take part in the study any longer (n=2). Eventually, 23 patients completed test2. Three patients were not able to perform the 6MW at T2 because of overuse injuries at the foot. All subjects were adults with a mean age of 40.5 (SD 12.8) years and a mean body mass index of 26.9 (SD 4.6). Fourteen of the subjects were diagnosed with depressive disorder, two had bipolar I disorder (in the depressed phase) and seven suffered from adjustment disorder with mixed anxiety and depressed mood.
 
Changes in severity of depression and gross motor functioning after 8 weeks treatment
Performances on gross motor functioning tests and the IDS-SR scores at the time of T1 and T2, as well as differences before and after 8 weeks treatment (Δ = T2 – T1) are presented in table 1.
 
Depression severity
In accordance to the IDS-SR interpretation criteria, 3 patients could be categorized as mildly, 5 as moderately, 8 as severely and 7 as very severely depressed at the time of T1. The groups mean score at this time was 41.3, meaning the group as a whole was severely depressed. After 8 weeks treatment, 83% of the patients had a lower score on the questionnaire. Three patients had a higher score and one patient stayed status quo. The group mean was now 34.9, indicating the group of patients partially recovered and became moderately depressed. The group thus had an average improvement of 6.4  scale points or 15,6% improvement.
 
Gross motor functioning
As regards the 6MWT, patients walked more distance and thus faster during test 2, compared to T1. At the time of T1 the patient group covered a mean distance of 580.3  meters at an average walking speed of 5.8 km/h. During T2 AWD and AWS were respectively 633.2 meters and 6.3 km/h, meaning a group improvement of 52.9 meters and 0.5 km/h. The average amount of steps per fifty meters did not significantly differ between the 2 testing periods, so we can assume that the average step length did not improve.

Sixteen subjects (70%) performed better on the second plate tapping test compared to the first. On average the group significantly improved by 1.13 seconds
Of all gross motor functioning parameters, the most significant improvement was on ACS. Patients cycled 10.8 rotations/minute faster during the second test at the same work load. Only 4 patients (17%) did not improve.

Summarized, the patients improved on every gross motor parameter except for SFM  after 8 weeks of treatment.
 
Association between severity of depression and degree of gross motor retardation 
As indicated by the direction of the correlation coefficients (table 2), higher IDS-SR scores tend to relate with worse performance on the gross motor tasks. However, the relationships before treatment are weak and not significant. The strongest relationships were found after 8 weeks treatment. Moderate to good significant associations were observed between IDS2 and TWD2, AWS2 and PT2.
 
Association between changes in severity of depression and gross motor functioning
 
The correlation coefficients were not signifuicant (varied from -0.08 to -0.14), indicating that there is no association between patients’ improvement on gross motor functioning and recovery of depression.
 
Discussion
As expected, patients became less severely depressed after 8 weeks treatment and with the exception of stride length, they improved on every gross motor parameter. Stride length of patients did significantly improve in other longitudinal studies (8, 9). The discrepancy between their finding and the result of the present study could be due to different measurement methods (25-meter walk test at self selected pace and video-analysis versus 6MWT), composition of the sample in terms of subtype of depression (see below: limitations) and different drug treatment. The patients in one study Lecrubier (8) only received venlafaxine, where patients in this study used different types of antidepressants in combination with antipsychotics and benzodiazepines. However, it is possible that stride length will improve in the weeks or months following the last measurements, because previous research suggested that stride length recovers more slowly than speed related parameters of walking (8).
 
Although there is a lot of evidence that severity of PR and severity of depression are related, these associations might only account for some aspects of PR. Previous research (2, 7, 16, 17) showed associations between severity of depression and degree of impairment on cognitive and fine motor parameters. In the gross motor domain only 24h activity level was studied and found to be related to severity of depression (19). Results of the present study could only find significant associations between severity of depression and degree of TWD, AWS and PT impairment.
 
Based on our results, the hypothesis that (partial) recovery of depression is associated with improvement in gross motor functioning could not be confirmed. Significant improvement of depression, TWD, AWS, PT and ACD were observed, but little to no relationships was found between these parameters. The lack of associations suggests that different factors are responsible for recovery of depression and improvement in gross motor retardation.
 
Limitations of the study
The most important limitation of the present study is the heterogeneity of the sample in terms of subgroups of depression. Presence of melancholia, comorbid anxiety and personality disorders may affect both the profile of PR and the speed and completeness of response to treatment (5). Because of the relatively small sample, we did not distinguish between melancholic and non-melancholic depression. Moreover, 7 patients were diagnosed with adjustment disorder with mixed anxiety and depressed mood. Therefore results may be difficult to interpret.
 
Subjects of the present study had different diagnoses but they were only included if they had clinically observed PR. This observation however was not confirmed by further standardized subjective (such as the SRRS) or objective measurements (comparison to healthy controls). Research indicate that gait and upper/lower limb movement are slowed in depressed patients compared to controls, but these findings were not based on performance on the 6MWT, the plate tapping test or a cycle ergometer test. Reference values of 6MWT and plate tapping performance do exist for a healthy Flemish population, but only for younger adults (PT) or older adults (6MWT) (31).
 
Another limitation is that the sample of the present study was also heterogeneous in terms of medication. Research suggests that some types of medication have a better effect on PR than others (4). Some types of medication can negatively interfere with motor functioning (7). Patients participating in this study took different types and combinations of antidepressants, antipsychotics and benzodiazepines. These types of drugs act on the nervous system and possible side-effects are sedation, fatigue and extrapyramidal symptoms (32). It would have been unethical and impossible to deprive all patients from this medication for the purpose of this study, but perhaps a more homogeneous group in terms of medication could have resulted in stronger associations between recovery of depression and recovery of PR.
 
Further directions
Further research is necessary to determine whether slowed limb movement in depressed patients with PR manifests itself during the 6MWT, the plate tapping test and a submaximal cycle ergometer test and to determine whether the relationship between severity of depression and severity of PR also applies to other aspects of gross motor retardation than the amount of activity during 24h. Longitudinal studies have begun to clarify the relationship between recovery of depression and changes in gross motor retardation but also on this topic more research is needed. Such research should preferably use a homogeneous sample in terms subgroup of affect disorder and medication use.


 

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