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Psychomotor retardation in elderly depressed patients
Journal of Affective Disorders 81 (2004) 73 – 77 www.elsevier.com/locate/jad
Brief report
Psychomotor retardation in elderly depressed patients M.P.B.I. Pier a,*, W. Hulstijn b,c, B.G.C. Sabbe a,c a
Department of Psychiatry, University Medical Centre, Reinier Postlaan 10, Nijmegen 6525 GC, The Netherlands b Nijmegen Institute of Cognition and Information (NICI), University of Nijmegen, The Netherlands c Collaborative Antwerp Psychiatric Research Institute (CAPRI), University of Antwerp, Belgium Received 25 March 2003; received in revised form 6 August 2003; accepted 8 August 2003
Abstract Background: The results of previous studies on psychomotor retardation (PR) in elderly depressed patients are inconsistent. The purpose of this study was (1) to try and establish whether elderly depressed patients show PR, and (2) if so, which process (cognitive/motor or both) is mainly slowed? Methods: Twelve elderly depressed patients and healthy controls (age: 70) were compared on figure copying tasks in which the cognitive task difficulty was manipulated. Results: Both initiation time (IT) and movement time (MT) were prolonged in the patient group. The effects of the cognitive manipulations were not larger in the patient group. Limitations: The sample size was small. Furthermore, patients were not medication free. Conclusions: A cognitive and a more pronounced motor retardation was found. Clinicians should be aware of this at least additive effect of aging and depression on PR in elderly patients. D 2003 Elsevier B.V. All rights reserved. Keywords: Depression; Elderly; Psychomotor retardation; Cognitive; Motor
1. Introduction Psychomotor retardation (PR), a slowing of mental and motor activity, is an important symptom of a major depression (Sobin and Sackeim, 1997). However, in elderly depressed patients (70 years), psychomotor disturbances may be different from that in middle-aged patients (40 years) (Ayuso-Gutierrez, 1984; Ruegg et al., 1988; Sobin and Sackeim, 1997). The amount of PR generally observed in middle-aged depressed patients may become less pronounced in elderly depressed patients – because * Corresponding author. Tel.: +31-24-3610207; fax: +31-243540561. E-mail address: [email protected] (M.P.B.I. Pier). 0165-0327/$ - see front matter D 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2003.08.002
aging already causes slowing (Cerella et al., 1993) – or, alternatively, age and depression may interact, resulting in a more pronounced PR in elderly depression. The results of the few studies that investigated this question with objective and sensitive measures are inconsistent. Evidence was found for both cognitive and motor slowing (Tarbuck and Paykel, 1995; Beats et al., 1996), motor slowing only (Hart and Kwentus, 1987; Nebes et al., 1998) and no slowing at all (Nebes et al., 1992). It is possible that differences in task complexity contributed to these inconsistent findings. In the present study, we therefore deliberately varied task complexity. Two figure copying tasks, also used in earlier research by our group, in which the cognitive varia-
74
M.P.B.I. Pier et al. / Journal of Affective Disorders 81 (2004) 73–77
bles complexity and familiarity were manipulated, were used (Van Hoof et al., 1993; Sabbe et al., 1996, 1999). Initiation time (IT) is assumed to reveal mainly cognitive processes (perception, temporary storage and sequence planning), while movement time (MT) is more indicative of motor disturbances. Earlier studies with middle-aged depressed patients revealed both cognitive and motor retardation in these patients (both IT and MT were longer and patients had more problems copying more difficult figures) (Sabbe et al., 1996). In short, the following questions were addressed in this study: (1) Do elderly depressed patients show PR compared to controls?, and (2) If so, which process (cognitive/motor or both) is mainly slowed?
2. Method Twelve elderly depressed inpatients (age: 70 F 3) meeting DSM-IV criteria (APA, 1994) for Major Depression (10 unipolar/2 bipolar) were compared with 12 healthy controls matched for age (73 F 4), gender and education. Each group consisted of 11 women and 1 man. At the time of testing, patients received conventional medication (three patients: serotonin re-uptake inhibitors (SSRIs), six: tricyclic antidepressants (TCAs), three: lithium and one: Risperdal). Most patients had already been hospitalized for several months. The tasks were similar to those used by Sabbe et al. (1996). After giving their written informed consent, participants had to copy stimulus figures presented on a monitor as fast and as accurately as possible. In task 1, lines and figures had to be copied (Fig. 1). The lines and figures were analyzed separately. The figures varied in complexity (simple: angle/circle, complex: diamond/wave pattern). All lines and figures were presented six times in fixed random order. In task 2, 12 more difficult figures had to be copied. They consisted of four line segments each but differed in terms of their familiarity (Fig. 1: letters, familiar figures and unfamiliar patterns). As soon as participants started drawing, the stimulus figure disappeared from the screen. Only in task 2, stimulus reinspection was possible (though not encouraged) by touching a red square on the digitizer with the pen.
Fig. 1. The stimulus figures of task 1 and examples of the stimulus figures of task 2.
Illness severity was measured by the Geriatric Depression Scale (GDS) (Yesavage and Brink, 1982). A Calcomp 2300 digitizer, a pressure-sensitive pen, and a PC were used. The pen-point position was sampled with a 0.1-mm precision at 100 Hz. IT (time between stimulus presentation and the start of the first drawing movement) and MT (time between the start of the first and the completion of the last drawing movement) were derived. In task 2, reinspection time (Treinspect: time between the moment the participant touched the red square and the moment he/ she resumed drawing) was also determined. Treinspect was not included in MT.
3. Results The results are presented in Table 1. The patient group was moderately depressed (GDS: patients: 18 ( F 5), controls: 2.5 ( F 3)). In both copying tasks, significant or nearly significant group differences were found for both IT and MT. In task 2, although the patients had longer ITs and reinspection times compared to controls, these differences failed to reach
M.P.B.I. Pier et al. / Journal of Affective Disorders 81 (2004) 73–77
75
Table 1 Means and standard deviations for the patients and controls for tasks 1 and 2 and the results of the general linear method repeated measures analysis of variance Group Patients Task 1 (lines) IT MT
Controls
Group
M
S.D.
M
S.D.
F(1,22)
1.186 0.783
0.406 0.561
0.838 0.414
0.121 0.129
7.43* 4.53*
Task 1 (figures) IT MT
1.188 2.414
0.447 1.276
0.868 1.389
0.108 0.283
5.35* 6.76*
0.374 0.155 0.430 0.677
#
Task 2 IT Treinspect IT + Treinspect MT
1.834 0.263 2.097 4.187
0.685 0.301 0.789 1.501
1.424 0.076 1.500 2.860
3.32 3.68# 5.31* 7.80*
Group complexity F(1,22)
Complexity F(1,22)
1.68 7.26*
25.73*** 62.10***
Group familiarity F(2,21)
Familiarity F(2,21)
1.38 2.34 5.08* 4.62*
13.20*** 6.51** 16.34*** 64.33***
# p < 0.10. * p < 0.05. ** p < 0.01. *** p < 0.001.
significance. However, when the two measures were added, a significant group difference could be observed. Patients did not produce larger drawings ( F < 1). They also did not make more errors. The effects of complexity (task 1) and familiarity (task 2) on IT were similar in both groups (the group by complexity and group by familiarity interactions were not significant) (Figs. 2 and 3). However, in task 2, when IT and Treinspect were summated, a significant group by familiarity interaction could be observed. There were significant group by complexity and group by familiarity interactions for MT, however, the relative lengthening of the MTs of the patients were rather similar in all conditions (task 1: simple: 167%, complex: 179%; task 2: letters: 146%, figures: 154%, patterns: 139%). In the patient group, correlations (Spearman, onetailed) were calculated between kinematic and clinical variables. GDS and use of hypnotics did not correlate with IT and MT. Use of antidepressants was substantially correlated with MT of task 1 only (MT-lines: rs = 0.59, P < 0.05; MT-figures: rs = 0.46, P < 0.10). Use of anxiolytics showed significant correlations
Fig. 2. Mean values and standard deviations (vertical lines) for initiation time (A) and movement time (B) as a function of figure complexity for task 1.
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M.P.B.I. Pier et al. / Journal of Affective Disorders 81 (2004) 73–77
Fig. 3. Mean values and standard deviations (vertical lines) for initiation time (A), movement time (B) and reinspection time (C) as a function of figure familiarity for task 2.
with IT and MT of task 2 only (IT: rs = 0.51, P < 0.05; MT: rs = 0.56, P < 0.05).
4. Discussion The geriatric depressed patients (as a group) were slower on all tasks than the controls. Both IT and MT were prolonged. In general, we may conclude that the elderly depressed patients showed considerable PR compared to their age-matched controls. The second question concerned the nature of this retardation. IT was significantly prolonged in the
depressed group (although in task 2 Treinspect had to be added to IT to make the group difference significant). The relative increases in IT shown by the depressed patients, calculated as a percentage of the control IT values, varied between 29% and 42%. In contrast, the relative increases of MT were much larger, particularly in task 1 (task 1: lines: 89%, figures: 74%; task 2: 46%). The MT increase of task 1 mainly reflects a possible primary motor slowing (not due to cognitive retardation), since the cognitive load of drawing a single stroke is minimal. The manipulation of figure complexity and familiarity was introduced to increase the processing load of the cognitive processes. The effects of these variables on IT were significant but very much alike for both groups, the only exception being the significant interaction between familiarity and the combination of IT and Treinspect in task 2. Taken together, our results suggest that the PR observed in the patient group was caused by both cognitive and motor factors. The motor component seemed to be stronger, but slowing in cognitive processes cannot be denied. This result is consistent with the findings of Tarbuck and Paykel (1995) and Beats et al. (1996), but inconsistent with those of Hart and Kwentus (1987) and Nebes et al. (1998), who demonstrated motor slowing only. Our study suggests that even if tasks are rather simple, then both cognitive and motor slowing can be found. The PR in our elderly depressed patients does not appear to be dissimilar from the PR in younger patients. Earlier, we found PR consisting of both cognitive and motor retardation in middle-aged depressed patients (Van Hoof et al., 1993; Sabbe et al., 1996, 1999). A limitation of our study is the fact that our patients used medication. Evidence for confounding effects of medication was found in the correlations between antidepressants and motor slowing, and anxiolytics and performance in the most complex task. It is generally known that TCAs negatively influence cognitive functions (Amado-Boccara et al., 1995). The influence of TCAs on motor tasks (e.g. task 1) has not yet been studied, but cannot be ruled out. Another explanation for the correlations is that patients with severe PR are also the ones that are more severely depressed and consequently receive more antidepressants and/or anxiolytics.
M.P.B.I. Pier et al. / Journal of Affective Disorders 81 (2004) 73–77
Our study showed that there is at least an additive effect of aging and depression on psychomotor speed of which clinicians should be aware.
References Amado-Boccara, I., Gougoulis, N., Poirier Littre´, M.F., Galinowski, A., Loˆo, H., 1995. Effects of antidepressants on cognitive functions: a review. Neurosci. Biobehav. Res. 3, 479 – 493. American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. Author, Washington, DC. Ayuso-Gutierrez, J.L., 1984. Later life depression: clinical and therapeutic aspects. In: Davis, J.H., Maas, J.W. (Eds.), The Affective Disorders. American Psychiatric Press, Washington, DC, pp. 203 – 210. Beats, B.C., Sahakian, B.J., Levy, R., 1996. Cognitive performance in tests sensitive to frontal lobe dysfunction in the elderly depressed. Psychol. Med. 26, 591 – 603. Cerella, J., Rybash, J., Hoyer, W., Commons, M.L., 1993. Adult Information Processing: Limits on Loss. Academic Press, California. Hart, R.P., Kwentus, J.A., 1987. Psychomotor slowing and subcortical-type dysfunction in depression. J. Neurol. Neurosurg. Psychiatry 50, 1263 – 1266. Nebes, R.D., Brady, C.B., Reynolds, C.F., 1992. Cognitive slowing
77
in Alzheimer’s disease and geriatric depression. J. Gerontol. 47, 331 – 336. Nebes, R.D., Halligan, E.M., Rosen, J., Reynolds, C.F., 1998. Cognitive and motor slowing in Alzheimer’s disease and geriatric depression. J. Int. Neuropsychol. Soc. 4, 426 – 434. Ruegg, R.G., Zisook, S., Swerdlow, N.R., 1988. Depression in the aged: an overview. In: Jeste, D.V., Zisook, S. (Eds.), Psychosis and Depression in the Elderly. The Psychiatric Clinics of North America, vol. 1. Saunders, Philadelphia, pp. 83 – 99. Sabbe, B., Hulstijn, W., Van Hoof, J., Zitman, F., 1996. Retardation and antidepressant treatment: changes in fine motor retardation in depressed patients treated with fluoxetine. J. Affect. Disord. 40, 149 – 157. Sabbe, B., Hulstijn, W., Van Hoof, J., Tuynman Qua, H.G., Zitman, F., 1999. Retardation in depression: assessment by means of simple motor tasks. J. Affect. Disord. 55, 39 – 44. Sobin, C., Sackeim, H.A., 1997. Psychomotor symptoms of depression. Am. J. Psychiatry 154, 4 – 17. Tarbuck, A.F., Paykel, E.S., 1995. Effects of major depression on the cognitive function of younger and older subjects. Psychol. Med. 25, 285 – 295. Van Hoof, J., Hulstijn, W., Van Mier, H., Pagen, M., 1993. Figure drawing and psychomotor retardation: preliminary report. J. Affect. Disord. 29, 263 – 266. Yesavage, J.A., Brink, T., 1982. Development and validation of a geriatric depression screening scale: a preliminary report. J. Psychiat. Res. 17, 37 – 49.
Brief report
Psychomotor retardation in elderly depressed patients M.P.B.I. Pier a,*, W. Hulstijn b,c, B.G.C. Sabbe a,c a
Department of Psychiatry, University Medical Centre, Reinier Postlaan 10, Nijmegen 6525 GC, The Netherlands b Nijmegen Institute of Cognition and Information (NICI), University of Nijmegen, The Netherlands c Collaborative Antwerp Psychiatric Research Institute (CAPRI), University of Antwerp, Belgium Received 25 March 2003; received in revised form 6 August 2003; accepted 8 August 2003
Abstract Background: The results of previous studies on psychomotor retardation (PR) in elderly depressed patients are inconsistent. The purpose of this study was (1) to try and establish whether elderly depressed patients show PR, and (2) if so, which process (cognitive/motor or both) is mainly slowed? Methods: Twelve elderly depressed patients and healthy controls (age: 70) were compared on figure copying tasks in which the cognitive task difficulty was manipulated. Results: Both initiation time (IT) and movement time (MT) were prolonged in the patient group. The effects of the cognitive manipulations were not larger in the patient group. Limitations: The sample size was small. Furthermore, patients were not medication free. Conclusions: A cognitive and a more pronounced motor retardation was found. Clinicians should be aware of this at least additive effect of aging and depression on PR in elderly patients. D 2003 Elsevier B.V. All rights reserved. Keywords: Depression; Elderly; Psychomotor retardation; Cognitive; Motor
1. Introduction Psychomotor retardation (PR), a slowing of mental and motor activity, is an important symptom of a major depression (Sobin and Sackeim, 1997). However, in elderly depressed patients (70 years), psychomotor disturbances may be different from that in middle-aged patients (40 years) (Ayuso-Gutierrez, 1984; Ruegg et al., 1988; Sobin and Sackeim, 1997). The amount of PR generally observed in middle-aged depressed patients may become less pronounced in elderly depressed patients – because * Corresponding author. Tel.: +31-24-3610207; fax: +31-243540561. E-mail address: [email protected] (M.P.B.I. Pier). 0165-0327/$ - see front matter D 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2003.08.002
aging already causes slowing (Cerella et al., 1993) – or, alternatively, age and depression may interact, resulting in a more pronounced PR in elderly depression. The results of the few studies that investigated this question with objective and sensitive measures are inconsistent. Evidence was found for both cognitive and motor slowing (Tarbuck and Paykel, 1995; Beats et al., 1996), motor slowing only (Hart and Kwentus, 1987; Nebes et al., 1998) and no slowing at all (Nebes et al., 1992). It is possible that differences in task complexity contributed to these inconsistent findings. In the present study, we therefore deliberately varied task complexity. Two figure copying tasks, also used in earlier research by our group, in which the cognitive varia-
74
M.P.B.I. Pier et al. / Journal of Affective Disorders 81 (2004) 73–77
bles complexity and familiarity were manipulated, were used (Van Hoof et al., 1993; Sabbe et al., 1996, 1999). Initiation time (IT) is assumed to reveal mainly cognitive processes (perception, temporary storage and sequence planning), while movement time (MT) is more indicative of motor disturbances. Earlier studies with middle-aged depressed patients revealed both cognitive and motor retardation in these patients (both IT and MT were longer and patients had more problems copying more difficult figures) (Sabbe et al., 1996). In short, the following questions were addressed in this study: (1) Do elderly depressed patients show PR compared to controls?, and (2) If so, which process (cognitive/motor or both) is mainly slowed?
2. Method Twelve elderly depressed inpatients (age: 70 F 3) meeting DSM-IV criteria (APA, 1994) for Major Depression (10 unipolar/2 bipolar) were compared with 12 healthy controls matched for age (73 F 4), gender and education. Each group consisted of 11 women and 1 man. At the time of testing, patients received conventional medication (three patients: serotonin re-uptake inhibitors (SSRIs), six: tricyclic antidepressants (TCAs), three: lithium and one: Risperdal). Most patients had already been hospitalized for several months. The tasks were similar to those used by Sabbe et al. (1996). After giving their written informed consent, participants had to copy stimulus figures presented on a monitor as fast and as accurately as possible. In task 1, lines and figures had to be copied (Fig. 1). The lines and figures were analyzed separately. The figures varied in complexity (simple: angle/circle, complex: diamond/wave pattern). All lines and figures were presented six times in fixed random order. In task 2, 12 more difficult figures had to be copied. They consisted of four line segments each but differed in terms of their familiarity (Fig. 1: letters, familiar figures and unfamiliar patterns). As soon as participants started drawing, the stimulus figure disappeared from the screen. Only in task 2, stimulus reinspection was possible (though not encouraged) by touching a red square on the digitizer with the pen.
Fig. 1. The stimulus figures of task 1 and examples of the stimulus figures of task 2.
Illness severity was measured by the Geriatric Depression Scale (GDS) (Yesavage and Brink, 1982). A Calcomp 2300 digitizer, a pressure-sensitive pen, and a PC were used. The pen-point position was sampled with a 0.1-mm precision at 100 Hz. IT (time between stimulus presentation and the start of the first drawing movement) and MT (time between the start of the first and the completion of the last drawing movement) were derived. In task 2, reinspection time (Treinspect: time between the moment the participant touched the red square and the moment he/ she resumed drawing) was also determined. Treinspect was not included in MT.
3. Results The results are presented in Table 1. The patient group was moderately depressed (GDS: patients: 18 ( F 5), controls: 2.5 ( F 3)). In both copying tasks, significant or nearly significant group differences were found for both IT and MT. In task 2, although the patients had longer ITs and reinspection times compared to controls, these differences failed to reach
M.P.B.I. Pier et al. / Journal of Affective Disorders 81 (2004) 73–77
75
Table 1 Means and standard deviations for the patients and controls for tasks 1 and 2 and the results of the general linear method repeated measures analysis of variance Group Patients Task 1 (lines) IT MT
Controls
Group
M
S.D.
M
S.D.
F(1,22)
1.186 0.783
0.406 0.561
0.838 0.414
0.121 0.129
7.43* 4.53*
Task 1 (figures) IT MT
1.188 2.414
0.447 1.276
0.868 1.389
0.108 0.283
5.35* 6.76*
0.374 0.155 0.430 0.677
#
Task 2 IT Treinspect IT + Treinspect MT
1.834 0.263 2.097 4.187
0.685 0.301 0.789 1.501
1.424 0.076 1.500 2.860
3.32 3.68# 5.31* 7.80*
Group complexity F(1,22)
Complexity F(1,22)
1.68 7.26*
25.73*** 62.10***
Group familiarity F(2,21)
Familiarity F(2,21)
1.38 2.34 5.08* 4.62*
13.20*** 6.51** 16.34*** 64.33***
# p < 0.10. * p < 0.05. ** p < 0.01. *** p < 0.001.
significance. However, when the two measures were added, a significant group difference could be observed. Patients did not produce larger drawings ( F < 1). They also did not make more errors. The effects of complexity (task 1) and familiarity (task 2) on IT were similar in both groups (the group by complexity and group by familiarity interactions were not significant) (Figs. 2 and 3). However, in task 2, when IT and Treinspect were summated, a significant group by familiarity interaction could be observed. There were significant group by complexity and group by familiarity interactions for MT, however, the relative lengthening of the MTs of the patients were rather similar in all conditions (task 1: simple: 167%, complex: 179%; task 2: letters: 146%, figures: 154%, patterns: 139%). In the patient group, correlations (Spearman, onetailed) were calculated between kinematic and clinical variables. GDS and use of hypnotics did not correlate with IT and MT. Use of antidepressants was substantially correlated with MT of task 1 only (MT-lines: rs = 0.59, P < 0.05; MT-figures: rs = 0.46, P < 0.10). Use of anxiolytics showed significant correlations
Fig. 2. Mean values and standard deviations (vertical lines) for initiation time (A) and movement time (B) as a function of figure complexity for task 1.
76
M.P.B.I. Pier et al. / Journal of Affective Disorders 81 (2004) 73–77
Fig. 3. Mean values and standard deviations (vertical lines) for initiation time (A), movement time (B) and reinspection time (C) as a function of figure familiarity for task 2.
with IT and MT of task 2 only (IT: rs = 0.51, P < 0.05; MT: rs = 0.56, P < 0.05).
4. Discussion The geriatric depressed patients (as a group) were slower on all tasks than the controls. Both IT and MT were prolonged. In general, we may conclude that the elderly depressed patients showed considerable PR compared to their age-matched controls. The second question concerned the nature of this retardation. IT was significantly prolonged in the
depressed group (although in task 2 Treinspect had to be added to IT to make the group difference significant). The relative increases in IT shown by the depressed patients, calculated as a percentage of the control IT values, varied between 29% and 42%. In contrast, the relative increases of MT were much larger, particularly in task 1 (task 1: lines: 89%, figures: 74%; task 2: 46%). The MT increase of task 1 mainly reflects a possible primary motor slowing (not due to cognitive retardation), since the cognitive load of drawing a single stroke is minimal. The manipulation of figure complexity and familiarity was introduced to increase the processing load of the cognitive processes. The effects of these variables on IT were significant but very much alike for both groups, the only exception being the significant interaction between familiarity and the combination of IT and Treinspect in task 2. Taken together, our results suggest that the PR observed in the patient group was caused by both cognitive and motor factors. The motor component seemed to be stronger, but slowing in cognitive processes cannot be denied. This result is consistent with the findings of Tarbuck and Paykel (1995) and Beats et al. (1996), but inconsistent with those of Hart and Kwentus (1987) and Nebes et al. (1998), who demonstrated motor slowing only. Our study suggests that even if tasks are rather simple, then both cognitive and motor slowing can be found. The PR in our elderly depressed patients does not appear to be dissimilar from the PR in younger patients. Earlier, we found PR consisting of both cognitive and motor retardation in middle-aged depressed patients (Van Hoof et al., 1993; Sabbe et al., 1996, 1999). A limitation of our study is the fact that our patients used medication. Evidence for confounding effects of medication was found in the correlations between antidepressants and motor slowing, and anxiolytics and performance in the most complex task. It is generally known that TCAs negatively influence cognitive functions (Amado-Boccara et al., 1995). The influence of TCAs on motor tasks (e.g. task 1) has not yet been studied, but cannot be ruled out. Another explanation for the correlations is that patients with severe PR are also the ones that are more severely depressed and consequently receive more antidepressants and/or anxiolytics.
M.P.B.I. Pier et al. / Journal of Affective Disorders 81 (2004) 73–77
Our study showed that there is at least an additive effect of aging and depression on psychomotor speed of which clinicians should be aware.
References Amado-Boccara, I., Gougoulis, N., Poirier Littre´, M.F., Galinowski, A., Loˆo, H., 1995. Effects of antidepressants on cognitive functions: a review. Neurosci. Biobehav. Res. 3, 479 – 493. American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. Author, Washington, DC. Ayuso-Gutierrez, J.L., 1984. Later life depression: clinical and therapeutic aspects. In: Davis, J.H., Maas, J.W. (Eds.), The Affective Disorders. American Psychiatric Press, Washington, DC, pp. 203 – 210. Beats, B.C., Sahakian, B.J., Levy, R., 1996. Cognitive performance in tests sensitive to frontal lobe dysfunction in the elderly depressed. Psychol. Med. 26, 591 – 603. Cerella, J., Rybash, J., Hoyer, W., Commons, M.L., 1993. Adult Information Processing: Limits on Loss. Academic Press, California. Hart, R.P., Kwentus, J.A., 1987. Psychomotor slowing and subcortical-type dysfunction in depression. J. Neurol. Neurosurg. Psychiatry 50, 1263 – 1266. Nebes, R.D., Brady, C.B., Reynolds, C.F., 1992. Cognitive slowing
77
in Alzheimer’s disease and geriatric depression. J. Gerontol. 47, 331 – 336. Nebes, R.D., Halligan, E.M., Rosen, J., Reynolds, C.F., 1998. Cognitive and motor slowing in Alzheimer’s disease and geriatric depression. J. Int. Neuropsychol. Soc. 4, 426 – 434. Ruegg, R.G., Zisook, S., Swerdlow, N.R., 1988. Depression in the aged: an overview. In: Jeste, D.V., Zisook, S. (Eds.), Psychosis and Depression in the Elderly. The Psychiatric Clinics of North America, vol. 1. Saunders, Philadelphia, pp. 83 – 99. Sabbe, B., Hulstijn, W., Van Hoof, J., Zitman, F., 1996. Retardation and antidepressant treatment: changes in fine motor retardation in depressed patients treated with fluoxetine. J. Affect. Disord. 40, 149 – 157. Sabbe, B., Hulstijn, W., Van Hoof, J., Tuynman Qua, H.G., Zitman, F., 1999. Retardation in depression: assessment by means of simple motor tasks. J. Affect. Disord. 55, 39 – 44. Sobin, C., Sackeim, H.A., 1997. Psychomotor symptoms of depression. Am. J. Psychiatry 154, 4 – 17. Tarbuck, A.F., Paykel, E.S., 1995. Effects of major depression on the cognitive function of younger and older subjects. Psychol. Med. 25, 285 – 295. Van Hoof, J., Hulstijn, W., Van Mier, H., Pagen, M., 1993. Figure drawing and psychomotor retardation: preliminary report. J. Affect. Disord. 29, 263 – 266. Yesavage, J.A., Brink, T., 1982. Development and validation of a geriatric depression screening scale: a preliminary report. J. Psychiat. Res. 17, 37 – 49.