Acta psychiat. scand. (1975) 51, 42-50 Psychochemistry Institute (Head: Professor 0. 1. Rafaelsen), and the University Department of Psychiatry (Heads: Professor V . Lunn, Professor 0. J . Rafaelsen, T . Vangguard, E. Dein), Rigshospitalet, Copenhagen, Denmark
DEPRESSION: I N F L U E N C E O N T I M E E S T I M A T I O N A N D T I M E EXPERIENCE P. BECH
Time studies are partly concerned with time estimation partly with time experience. In a study of depression both principles were applied. Depression did not influence time estimation, but, on the other hand, the patients did report a slowing down of time (change in time experience). An item analysis of Beck’s and Hamilton’s rating scales showed that the disturbance in time experience accompanies items referring mainly to mood changes, only to a small extent to somatic symptoms, and not at all to changes in the psychomotor activity. Key words. Depression - time estimation - time experience.
Clinically several authors have found that depression, especially endogenous d e pression, is associated with a change in time experience, i. e., time seems to pass by very slowly (Struus (1928), von Gebsuttel (1928), Kloos (1938), and Schneemann (1962)). On the other hand, there is experimental evidence that depression does not affect time estimation, i. e., estimation of the duration of short time intervals (Bouchurd (1926), Giehm (1931), Lewis (1931), Mezey & Cohen (1961), Melges & Fougerousse (1966), Dilling & Rabin (1967), Lehmann (1967)). However, the experimental methods in these studies suffer from a lack of differentiation between ‘objective’ and ‘subjective’ estimation of time, a differentiation which in a previous investigation we have found necessary and meaningful (Bech et ul. (1973)). In the present study, we have measured the influence of depression on ‘objective’ and ‘subjective’ time estimation in relation to time experience.
METHODS
Study 1 Subjects. The subjects comprised 28 psychiatric inpatients, and the distribution by different diagnostic groups was:
43 I Endogenous depression (n = 6,mean age 47,range 35-60). I1 Reactive depressive psychosis (n = 5,mean age 43,range 28-60). I11 Non-psychotic depression, i. e., personality disorders with depressive symptomatology (n = 6,mean age 42,range 31-53). IV Organic brain syndrome (n = 5,mean age 55,range 50-59). V Non-depressed psychiatric controls, i. e., personality disorders without depressive symptomatology (n = 6,mean age 43,range 30-58). The patients were tested shortly after their admission to the hospital during the period of preliminary clinical investigation and before treatment was started. After recovery or improvement sufficient for discharge from the hospital, the patients were retested. The time of investigation was always between 8.00 and 9.00 a. m. As non-depressed normal controls, we used the subjects from a cannabis study (Bech et al. (1973),(n = 8, mean age 25,range 21-29). Apparatus. The car simulator used in this study has been described in our previous reports (Bech et al. (1973), Rafaelsen et al. (1973), Bech et al. (1974)). This test model is built up like the front half of a car, and a picture from a movable cyclorama is continuously projected on the windshield, giving the subject the impression of driving on a variable test course. Time estimation was based on a standard driving period of 6 minutes during which the subject drove 3 minutes with a speed limit of 40 km/h and 3 minutes with a speed limit of 70 km/h. When the standard period had passed, the subject estimated the duration of the driving at 40 km/h and 70 km/h, respectively. The subjects estimated time in two different ways:
a. ‘Objectively’ using intellectual clues: “How long do you really think you have been driving?” b. ‘Subjectively’ using emotional or intuitive clues: “HOWlong do YOU really feel you have been driving?” Time experience was tested as the subjects impression as to whether time during the simulated car driving had passed rapidly or slowly or at medium speed. Study 2 Subjects. The subjects comprised 24 inpatients with depressive symptomatology, and they were tested before and after recovery (n = 47). On discharge from the hospital, 16 of the patients were diagnosed as suffering from endogenous depression. The remaining eight patients (in the following called non-endogenous depression) were diagnosed as atypical endogenous depression (five), dementia (one), neurosis (one), and paranoid psychosis (one). The mean age of the endogenous depression group was 55 years, range 31-71, and the mean age of the non-
44 endogenous depression group was 47 years, range 20-72. The time of investigation was always between 8.00 and 10.00 a. m. Procedure. As a measurement of the severity of depression we used Beck‘s selfrating scale (Beck et al. (1961)), Hamilton’s objective rating scale (Hamilton (1960)), and a global clinical assessment on an eleven point scale (no depression: 0-1; mild depression: 2-4; moderate depression: 5-7; and severe depression: 8-10). Time estimation. The subjects were instructed to administer the Beck scale themselves and to estimate two standard time intervals (of 5 minutes) while the questionnaire was completed. Time experience. As in study 1, we asked the subjects whether time was passing rapidly, slowly, or at medium speed. Time sense inventory. This questionnaire has been constructed by Melges & Fougerousse (1966). The scale consists of:
a. Items reflecting ‘world time’ versus ‘ego time’ (e. g.: “I seem to be going slower than the world”, “I seem to be going faster than the world”). b. Items reflecting the temporal perspective (e. g.: “I think very little about the future”, “I think very little about the past”, “I find the past, present, and future seem all muddled up and mixed together”). The statements were read out loud, and the subjects responded orally in terms of yes or no. RESULTS Study 1 Time estimation. The results for various diagnostic groups during 3 minutes of simultated car driving at 40 km/h and at 70 km/h are shown in Table 1 and 2, respectively. There were no statistically significant changes neither between the groups (Kruskal-Wallis one-way analysis of variance (Siege2 (1956)), nor within the groups (Wilcoxon matched pairs signed ranks test (Siege2 (1956)). In particular, there was no difference between ‘objective’ and ‘subjective’ time estimation. Time experience. As shown in Table 3, it is obvious that depression is associated with a slowing down of the experience of time. Although the strongest effect is seen for endogenous depression, the other groups of depression also seem to be affected. Study 2
As shown in Table 4,we found no statistically significant difference between the
45
Diagnostic groups
I
Endogenous depression
I1 Reactive depression I11 Non-psychotic depression IV V IV
Organic brain syndrome Controls (psychiatric) Controls (normal)
Before recovery (min)
After recovery (min)
Objective
Subjective
Objective
Subjective
3.3 (1.0- 5.0) 3.3 (2.5- 4.0) 4.5 (2.0- 6.0) 5.6 (3.0-120) 3.5 (1.0- 5.0) 4.3 (2.0- 7.0)
3.4 (1.0- 5.0) 3.3 (2.5- 4.0) 4.5 (2.0- 6.0) 6.0 (3.0-12.0) 3.5 (1.0- 5.0) 4.3 (2.0- 7.0)
3.6 (1.5- 6.0) 2.8 (2.0- 3.0) 5.2 (3.0-10.0) 4.5 (2.5- 8.0) 3.2 (1.8- 6.0)
3.6 (1.5- 6.0) 2.8 (2.0- 3.0) 5.2 (3.0-10.0) 4.5 (2.5- 8.0) 3.2 (1.8- 6.0)
’’
endogenous and non-endogenous group in the degree of depression measured by the total scores on Beck‘s and Hamilton’s scales or by the global clinical assessment (Mann-Whitney U test (Siegel (1956)). Time estimation. We found no difference between ‘objective’ and ‘subjective’ time estimation. Furthermore, we found no statistically significant difference between the two groups of depression (Mann-Whitney U test).
Diagnostic groups
Before recovery (min) Objective
Subjective
After recovery bin) Objective
Subjective
46
Table 3. Time experience before recovery. Number of subjects in various groups who felt that time was passing by rapidly, slowly or at medium speed
Diagnostic groups I Endogenous depression I1 Reactive depression I11 Non-psychotic depression
IV Organic brain syndrome V Controls (psychiatric) IV Controls (normal)
Slowly
Medium
Rapidly
6 2 3 0 0 0
0 1 2 4 6 6
0 2 1 1 0 0
T i m e experience.
1. Endogenous vs. non-endogenous depression. Using Fisher’s exact probability test (Siegel (1956)), we found no difference between endogenous and non-endogenous depression in the depressive state (out of the 14 patients who ihdicated that time passed by slowly, ten were endogenous and four were non-endogenous, against six and four respectively in the ten patients claiming that time passed by at normal or even at rapid speed).
2. Severity of depression. For all 24 depressive patients seen on 47 occasions (n = 47)the following was observed: a. Correlation analysis of the total scale scores. Time experience evaluated on a three point scale (rapidly = 1; medium = 2; and slowly = 3) correlated positively with the total scores on Beck‘s scale (Spearman’s correlation coefficient rs = 0.60, n = 47, P < 0.01), with the total scores on Hamilton’s scale (rs = 0.35, n = 47, P < 0.05),and with the global clinical assessment (r8 = 0.56, n = 47,P < 0.01). Table 4. Rating score, time estimation, and time experience in 24 patients in the depressive state
Study 2
I
Depression Endogenous n = 16
Beck (total score) Hamilton (total score) Clinical assessment Time estimation (min) First period (objective = subjective) Second period (objective = subjective)
I
Non-endogenous n=8
29.0 44.0 5.2
20.5 37.0 4.1
7.2 5.7
7.5 5.9
Time experience
Slowly Medium Rapidly
10 5 1
4
4 0
47
b. Step-by-step item analysis of Beck’s and Hamilton’s scales. A step-by-step analysis of Beck’s and Hamilton’s scales in relation to the global clinical assessment (Bech et al. (1975)) showed that only 12 of the 21 items of Beck‘s scale and six of the 17 items of Hamilton’s scale were valid in measuring the seventy of depressive states. The fundamental principle in this step-by-step analysis was to test the proportionality between the scores of an item and the results of time experience. For that purpose, our observations were related to a straight line through (0.0). The line was determined so that the rank-sum of the positive deviations between the line and the observations was equal to the rank-sum of the negative deviations. Then we made the following three criteria for validation of each item (Fig. 1). Calibration. The item should have a reasonable number of observations above zero as items where the majority of scores equal to zero are not useful. The criterion used here is to exclude items giving a slope of the line less than 0.01. Two items failed to fulfil this criterion on Beck’s scale: item I (self-punitive wishes) and item S (weight loss). On Hamilton’s scale, four items failed: item 14 (genital symptoms), item 15 (hypochondriasis), item 16 (weight loss), and item 17 (insight). Ascending monotonicity. The item score should increase proportionally with the time experience value. In order to study which items have this property, we arranged the data in three groups according to the results of the time experience, namely rapidly = 0, medium = 1, and slowly = 2. A test of the similarity of the level of the deviations between the line and the observations in the three groups was made by use of Kruskal-Wallis’ one-way analysis of variance (Siege1
ITEM NO.
TIME EXPERIENCE
Fig. l.Graphica2 representation of the item analysis of rating scales in relation to time experience for calibration, ascending monotonicity and dispersion.
48
(1956)). The significance level was 5 % (one-tailed test). Six items failed to fulfil this criterion on Beck’s scale: item G (self hate), item H (self accusations), item K (irritability), item 0 (work inhibition), item Q (fatigability), and item R (loss of appetite). On Hamilton’s scale, four items failed: item 9 (agitation), item 11 (anxiety, somatic), item 12 (somatic symptoms, gastrointestinal), and item 13 (somatic symptoms, general). Dispersion. The item score should, for a fixed value of the time experience, present the smallest possible variation. Before a reasonable comparison could be made, it was found necessary to adjust the items scores (by multiplication with suitable constants) so that the lines all had the same slope. Then the dispersion around the line for each item was compared to the item with least dispersion, using the Ansari-Bradley test (Ansari & Bradley (1960)), and items showing a significantly larger dispersion were excluded. The significance level was 5 % (twotailed test). Six items failed to fulfil this criterion on Beck‘s scale: item G (self hate), item J (crying spells), item L (social withdrawal), item 0 (work inhibition), item Q (fatigability), and item R (loss of appetite). On Hamilton’s scale, 14 items failed 2 (guilt), 3 (suicide), 4 (insomnia, initial), 5 (insomnia, middle), 6 (insomnia, delayed), 8 (retardation), 9 (agitation), 11 (anxiety somatic), 12 (somatic symptoms, gastrointestinal), 13 (somatic symptoms, general), 14 (genital symptoms), 15 (hypochondriasis), 16 (weight loss), 17 (insight). Eleven items on Beck‘s scale fulfilled our three criteria: A (depressed mood), B (pessimism), C (sense of failure), D (lack of satisfaction), E (guilty feeling), F (sense of punishment), M (indecisiveness), N (body image), P (sleep disturbance), T (somatic preoccupation), and W (loss of libido). Three items on Hamilton’s scale fulfilled the criteria: 1 (depressed mood), 7 (work and interest), and 10 (anxiety, psychic). Time sense inventory. Of the 24 subjects in the depressive state, only ten had positive scores on the inventory. Of these ten subjects, eight felt that they were going slower than the world (a distinction between ego time and world time), and five of the eight subjects also felt that the past, present, and future seemed all muddled up and mixed together (an altered temporal perspective). Only two of the ten subjects had an altered temporal perspective. Of the eight subjects with the distinction between ego time and world time, seven felt that time passed by slowly, and one felt that time passed by rapidly. All of the subjects but one were suffering from endogenous depression. According to the item of retardation on Hamilton’s scale, four had no or mild retardation, and four had moderate to severe retardation. Of the seven subjects with altered temporal perspective, six felt that time passed by slowly, and one felt that time passed by at medium speed. Of these subjects, four were suffering from endogenous depression. According to the item of retardation on Hamilton’s scale, four had no or mild retardation, and three had moderate to severe retardation.
49
DISCUSSION
In contrast to our previous cannabis study in which we could demonstrate a positive correlation between ‘subjective’ time estimation (an overestimation) and time experience (the subjects felt that time passed by very slowly), our findings both in study 1 and study 2 showed no effect of depression on ‘subjective’ time estimation, although the depressed patients felt that time passed by very slowly. However, our findings here are in accordance with Mezey & Cohen (1961), and Lehmann (1967). They found that depression is associated with a slowing down of the experience of time, but that time estimation, measured both with the verbal, production, and reproduction methods, was unimpaired. In study 1, we found no difference between endogenous and non-endogenous depression, neither on time estimation nor on time experience, and these findings were reproduced in study 2. On the other hand, in study 2 we could demonstrate that the slowing down of the experience of time paralleled the severity of depression measured by the use of rating scales. Furthermore, our item analysis showed that eleven items on Beck’s scale and three items on Hamilton’s scale fuIfiIled the criteria of calibration, ascending monotonicity, and dispersion, when tested in relation to time experience. The eleven items of Beck‘s scale were broadly identical with the twelve items we found valid in measuring the degree of depression which were parallel with the global clinical assessment. And the three items of Hamilton’s scale recurred in the six items we found valid in measuring the degree of depression. The items found valid when tested in relation to time experience are characterized by referring mainly to mood changes, only to a small extent to somatic symptoms, and not at all to changes in the psychomotor activity. As one of the first, Straus (1928) made the distinction between world time and ego time. It was his impression that depressive patients are very sensitive to the conflict which may arise between the immobility of their own emotions and thought and the changes which they see taking place around them in which they no longer play an active part. Using the time sense inventory constructed by Melges & Fougerousse (1966), we found that only a subgroup of the depressive patients had this distinction between world time and ego time, and we could find no convincing correlation to time experience or to the degree of retardation. Neither could we demonstrate any correlation between the temporal perspective and time experience. From our findings, therefore, we must conclude, that when the depressed patient tells us that “he is very sad and unhappy”, and when he tells that “time passes by very slowly”, he is trying to communicate the same or a similar experience - in two different frames of reference. ACKNOWLEDGMENT
Thanks are due to Jbrgen Nyboe, Rigshospitalet, Copenhagen, for statistical assistance.
50 REFERENCES Ansari, A . R., & R . A . Bradley (1960): Rank-sum tests for dispersion. Ann. Math. Statist. 31, 1174-1189. Bech, P., L . Rafaelsen & 0. J . Rafaelsen (1973): Cannabis and alcohol: effects on estimation of time and distance. Psychopharmacologia (Berl.) 32, 373-381. Bech, P., L. Rafaelsen & 0. J . Rafaelsen (1974): Cannabis: A psychopharmacological review. Dan. med. Bull. 21, 106-120. Bech, P., L . F . Gram, E. Dein, 0. Jacobsen, J . Vitger & T . G . Bolwig (1975): Quantitative rating of depressive states. Correlation between clinical assessment, self-rating scale (Beck), and objective rating scale (Hamilton). Acta psychiat. scand. In press. Beck, A . T., C . H . Ward, M . Mendelson, J . Mock & J . Erbaugh (1961): An inventory for measuring depression. Arch. gen. Psychiat. 4, 561-571. Bouchard, R . (1926): Sur l'tvaluation du temps dans certains troubles mentaux. Vigot FrBres, Paris. Dilling, C. A., & A . 1. Rabin (1967): Temporal experience in depressive states and schizophrenia. J. cons. Psychol. 31, 604-608. Gebsattel, V . E. von (1928): Zeitbezogenes Zwangsdenken in der Melancholie. Nervenartz I, 275-287. Giehm, G . von (193 1): Experimentell-psychologische Untersuchungen der Apperzeption des Zeitsinns bei Geisteskranken. Arch. Psychiat. Nervenkr. 95, 330-335. Hamilton, M . (1960): A rating scale for depression. J. Neurol. Neurosurg. Psychiat. 23, 56-62. Kloos, G . (1938): Storungen des Zeiterlebens in der endogenen Depression. Nervenartz 11, 225-244. Lehmann, H . E. (1967): Time and psychopathology. Ann. N. Y. Acad. Sci. 138, 798821. Lewis, A . (1931): The experience of time in mental disorder. Proc. roy. SOC.Med. 25, 61 1-620. Melges, F. T., & C . E. Fougerousse (1966): Time sense, emotions, and acute mental illness. J. psychiat. Res. 4, 127-140. Mezey, A . G., & S . 1. Cohen (1961): The effect of depressive illness on time judgment and time experience. J. Neurol. Neurosurg. Psychiat. 24,269-270. Rafaelsen, 0. J., P. Bech, J . Christiansen, H . Christrup, J . Nyboe & L . Rafaelsen (1973: Cannabis and alcohol: effect on simultated car driving. Science 173, 920923. Schneemann, K . von (1962): Bemerkungen zum Problem der Zeitstorung in endogenen Depressionen unter Berucksichtigung der Dependenzenlehre von Nicolai Hartmann. Confin. psychiat. (Basel) 5, 37-57. Siegel, S . (1956): Nonparametric statistics. McGraw-Hill, New York. Straus, E. (1928): Das Zeiterlebnis in der qdogenen Depression und in der psychopathischen Verstimmung. Mschr. Psychiat. Neurol. 68, 640-656.
.
Received June 18. 1974
Per Bech, M.D. Psychochemistry Institute Rigshospitalet 9 Blegdamsvej DK 2 1 0 Copenhagen Denmark
DEPRESSION: I N F L U E N C E O N T I M E E S T I M A T I O N A N D T I M E EXPERIENCE P. BECH
Time studies are partly concerned with time estimation partly with time experience. In a study of depression both principles were applied. Depression did not influence time estimation, but, on the other hand, the patients did report a slowing down of time (change in time experience). An item analysis of Beck’s and Hamilton’s rating scales showed that the disturbance in time experience accompanies items referring mainly to mood changes, only to a small extent to somatic symptoms, and not at all to changes in the psychomotor activity. Key words. Depression - time estimation - time experience.
Clinically several authors have found that depression, especially endogenous d e pression, is associated with a change in time experience, i. e., time seems to pass by very slowly (Struus (1928), von Gebsuttel (1928), Kloos (1938), and Schneemann (1962)). On the other hand, there is experimental evidence that depression does not affect time estimation, i. e., estimation of the duration of short time intervals (Bouchurd (1926), Giehm (1931), Lewis (1931), Mezey & Cohen (1961), Melges & Fougerousse (1966), Dilling & Rabin (1967), Lehmann (1967)). However, the experimental methods in these studies suffer from a lack of differentiation between ‘objective’ and ‘subjective’ estimation of time, a differentiation which in a previous investigation we have found necessary and meaningful (Bech et ul. (1973)). In the present study, we have measured the influence of depression on ‘objective’ and ‘subjective’ time estimation in relation to time experience.
METHODS
Study 1 Subjects. The subjects comprised 28 psychiatric inpatients, and the distribution by different diagnostic groups was:
43 I Endogenous depression (n = 6,mean age 47,range 35-60). I1 Reactive depressive psychosis (n = 5,mean age 43,range 28-60). I11 Non-psychotic depression, i. e., personality disorders with depressive symptomatology (n = 6,mean age 42,range 31-53). IV Organic brain syndrome (n = 5,mean age 55,range 50-59). V Non-depressed psychiatric controls, i. e., personality disorders without depressive symptomatology (n = 6,mean age 43,range 30-58). The patients were tested shortly after their admission to the hospital during the period of preliminary clinical investigation and before treatment was started. After recovery or improvement sufficient for discharge from the hospital, the patients were retested. The time of investigation was always between 8.00 and 9.00 a. m. As non-depressed normal controls, we used the subjects from a cannabis study (Bech et al. (1973),(n = 8, mean age 25,range 21-29). Apparatus. The car simulator used in this study has been described in our previous reports (Bech et al. (1973), Rafaelsen et al. (1973), Bech et al. (1974)). This test model is built up like the front half of a car, and a picture from a movable cyclorama is continuously projected on the windshield, giving the subject the impression of driving on a variable test course. Time estimation was based on a standard driving period of 6 minutes during which the subject drove 3 minutes with a speed limit of 40 km/h and 3 minutes with a speed limit of 70 km/h. When the standard period had passed, the subject estimated the duration of the driving at 40 km/h and 70 km/h, respectively. The subjects estimated time in two different ways:
a. ‘Objectively’ using intellectual clues: “How long do you really think you have been driving?” b. ‘Subjectively’ using emotional or intuitive clues: “HOWlong do YOU really feel you have been driving?” Time experience was tested as the subjects impression as to whether time during the simulated car driving had passed rapidly or slowly or at medium speed. Study 2 Subjects. The subjects comprised 24 inpatients with depressive symptomatology, and they were tested before and after recovery (n = 47). On discharge from the hospital, 16 of the patients were diagnosed as suffering from endogenous depression. The remaining eight patients (in the following called non-endogenous depression) were diagnosed as atypical endogenous depression (five), dementia (one), neurosis (one), and paranoid psychosis (one). The mean age of the endogenous depression group was 55 years, range 31-71, and the mean age of the non-
44 endogenous depression group was 47 years, range 20-72. The time of investigation was always between 8.00 and 10.00 a. m. Procedure. As a measurement of the severity of depression we used Beck‘s selfrating scale (Beck et al. (1961)), Hamilton’s objective rating scale (Hamilton (1960)), and a global clinical assessment on an eleven point scale (no depression: 0-1; mild depression: 2-4; moderate depression: 5-7; and severe depression: 8-10). Time estimation. The subjects were instructed to administer the Beck scale themselves and to estimate two standard time intervals (of 5 minutes) while the questionnaire was completed. Time experience. As in study 1, we asked the subjects whether time was passing rapidly, slowly, or at medium speed. Time sense inventory. This questionnaire has been constructed by Melges & Fougerousse (1966). The scale consists of:
a. Items reflecting ‘world time’ versus ‘ego time’ (e. g.: “I seem to be going slower than the world”, “I seem to be going faster than the world”). b. Items reflecting the temporal perspective (e. g.: “I think very little about the future”, “I think very little about the past”, “I find the past, present, and future seem all muddled up and mixed together”). The statements were read out loud, and the subjects responded orally in terms of yes or no. RESULTS Study 1 Time estimation. The results for various diagnostic groups during 3 minutes of simultated car driving at 40 km/h and at 70 km/h are shown in Table 1 and 2, respectively. There were no statistically significant changes neither between the groups (Kruskal-Wallis one-way analysis of variance (Siege2 (1956)), nor within the groups (Wilcoxon matched pairs signed ranks test (Siege2 (1956)). In particular, there was no difference between ‘objective’ and ‘subjective’ time estimation. Time experience. As shown in Table 3, it is obvious that depression is associated with a slowing down of the experience of time. Although the strongest effect is seen for endogenous depression, the other groups of depression also seem to be affected. Study 2
As shown in Table 4,we found no statistically significant difference between the
45
Diagnostic groups
I
Endogenous depression
I1 Reactive depression I11 Non-psychotic depression IV V IV
Organic brain syndrome Controls (psychiatric) Controls (normal)
Before recovery (min)
After recovery (min)
Objective
Subjective
Objective
Subjective
3.3 (1.0- 5.0) 3.3 (2.5- 4.0) 4.5 (2.0- 6.0) 5.6 (3.0-120) 3.5 (1.0- 5.0) 4.3 (2.0- 7.0)
3.4 (1.0- 5.0) 3.3 (2.5- 4.0) 4.5 (2.0- 6.0) 6.0 (3.0-12.0) 3.5 (1.0- 5.0) 4.3 (2.0- 7.0)
3.6 (1.5- 6.0) 2.8 (2.0- 3.0) 5.2 (3.0-10.0) 4.5 (2.5- 8.0) 3.2 (1.8- 6.0)
3.6 (1.5- 6.0) 2.8 (2.0- 3.0) 5.2 (3.0-10.0) 4.5 (2.5- 8.0) 3.2 (1.8- 6.0)
’’
endogenous and non-endogenous group in the degree of depression measured by the total scores on Beck‘s and Hamilton’s scales or by the global clinical assessment (Mann-Whitney U test (Siegel (1956)). Time estimation. We found no difference between ‘objective’ and ‘subjective’ time estimation. Furthermore, we found no statistically significant difference between the two groups of depression (Mann-Whitney U test).
Diagnostic groups
Before recovery (min) Objective
Subjective
After recovery bin) Objective
Subjective
46
Table 3. Time experience before recovery. Number of subjects in various groups who felt that time was passing by rapidly, slowly or at medium speed
Diagnostic groups I Endogenous depression I1 Reactive depression I11 Non-psychotic depression
IV Organic brain syndrome V Controls (psychiatric) IV Controls (normal)
Slowly
Medium
Rapidly
6 2 3 0 0 0
0 1 2 4 6 6
0 2 1 1 0 0
T i m e experience.
1. Endogenous vs. non-endogenous depression. Using Fisher’s exact probability test (Siegel (1956)), we found no difference between endogenous and non-endogenous depression in the depressive state (out of the 14 patients who ihdicated that time passed by slowly, ten were endogenous and four were non-endogenous, against six and four respectively in the ten patients claiming that time passed by at normal or even at rapid speed).
2. Severity of depression. For all 24 depressive patients seen on 47 occasions (n = 47)the following was observed: a. Correlation analysis of the total scale scores. Time experience evaluated on a three point scale (rapidly = 1; medium = 2; and slowly = 3) correlated positively with the total scores on Beck‘s scale (Spearman’s correlation coefficient rs = 0.60, n = 47, P < 0.01), with the total scores on Hamilton’s scale (rs = 0.35, n = 47, P < 0.05),and with the global clinical assessment (r8 = 0.56, n = 47,P < 0.01). Table 4. Rating score, time estimation, and time experience in 24 patients in the depressive state
Study 2
I
Depression Endogenous n = 16
Beck (total score) Hamilton (total score) Clinical assessment Time estimation (min) First period (objective = subjective) Second period (objective = subjective)
I
Non-endogenous n=8
29.0 44.0 5.2
20.5 37.0 4.1
7.2 5.7
7.5 5.9
Time experience
Slowly Medium Rapidly
10 5 1
4
4 0
47
b. Step-by-step item analysis of Beck’s and Hamilton’s scales. A step-by-step analysis of Beck’s and Hamilton’s scales in relation to the global clinical assessment (Bech et al. (1975)) showed that only 12 of the 21 items of Beck‘s scale and six of the 17 items of Hamilton’s scale were valid in measuring the seventy of depressive states. The fundamental principle in this step-by-step analysis was to test the proportionality between the scores of an item and the results of time experience. For that purpose, our observations were related to a straight line through (0.0). The line was determined so that the rank-sum of the positive deviations between the line and the observations was equal to the rank-sum of the negative deviations. Then we made the following three criteria for validation of each item (Fig. 1). Calibration. The item should have a reasonable number of observations above zero as items where the majority of scores equal to zero are not useful. The criterion used here is to exclude items giving a slope of the line less than 0.01. Two items failed to fulfil this criterion on Beck’s scale: item I (self-punitive wishes) and item S (weight loss). On Hamilton’s scale, four items failed: item 14 (genital symptoms), item 15 (hypochondriasis), item 16 (weight loss), and item 17 (insight). Ascending monotonicity. The item score should increase proportionally with the time experience value. In order to study which items have this property, we arranged the data in three groups according to the results of the time experience, namely rapidly = 0, medium = 1, and slowly = 2. A test of the similarity of the level of the deviations between the line and the observations in the three groups was made by use of Kruskal-Wallis’ one-way analysis of variance (Siege1
ITEM NO.
TIME EXPERIENCE
Fig. l.Graphica2 representation of the item analysis of rating scales in relation to time experience for calibration, ascending monotonicity and dispersion.
48
(1956)). The significance level was 5 % (one-tailed test). Six items failed to fulfil this criterion on Beck’s scale: item G (self hate), item H (self accusations), item K (irritability), item 0 (work inhibition), item Q (fatigability), and item R (loss of appetite). On Hamilton’s scale, four items failed: item 9 (agitation), item 11 (anxiety, somatic), item 12 (somatic symptoms, gastrointestinal), and item 13 (somatic symptoms, general). Dispersion. The item score should, for a fixed value of the time experience, present the smallest possible variation. Before a reasonable comparison could be made, it was found necessary to adjust the items scores (by multiplication with suitable constants) so that the lines all had the same slope. Then the dispersion around the line for each item was compared to the item with least dispersion, using the Ansari-Bradley test (Ansari & Bradley (1960)), and items showing a significantly larger dispersion were excluded. The significance level was 5 % (twotailed test). Six items failed to fulfil this criterion on Beck‘s scale: item G (self hate), item J (crying spells), item L (social withdrawal), item 0 (work inhibition), item Q (fatigability), and item R (loss of appetite). On Hamilton’s scale, 14 items failed 2 (guilt), 3 (suicide), 4 (insomnia, initial), 5 (insomnia, middle), 6 (insomnia, delayed), 8 (retardation), 9 (agitation), 11 (anxiety somatic), 12 (somatic symptoms, gastrointestinal), 13 (somatic symptoms, general), 14 (genital symptoms), 15 (hypochondriasis), 16 (weight loss), 17 (insight). Eleven items on Beck‘s scale fulfilled our three criteria: A (depressed mood), B (pessimism), C (sense of failure), D (lack of satisfaction), E (guilty feeling), F (sense of punishment), M (indecisiveness), N (body image), P (sleep disturbance), T (somatic preoccupation), and W (loss of libido). Three items on Hamilton’s scale fulfilled the criteria: 1 (depressed mood), 7 (work and interest), and 10 (anxiety, psychic). Time sense inventory. Of the 24 subjects in the depressive state, only ten had positive scores on the inventory. Of these ten subjects, eight felt that they were going slower than the world (a distinction between ego time and world time), and five of the eight subjects also felt that the past, present, and future seemed all muddled up and mixed together (an altered temporal perspective). Only two of the ten subjects had an altered temporal perspective. Of the eight subjects with the distinction between ego time and world time, seven felt that time passed by slowly, and one felt that time passed by rapidly. All of the subjects but one were suffering from endogenous depression. According to the item of retardation on Hamilton’s scale, four had no or mild retardation, and four had moderate to severe retardation. Of the seven subjects with altered temporal perspective, six felt that time passed by slowly, and one felt that time passed by at medium speed. Of these subjects, four were suffering from endogenous depression. According to the item of retardation on Hamilton’s scale, four had no or mild retardation, and three had moderate to severe retardation.
49
DISCUSSION
In contrast to our previous cannabis study in which we could demonstrate a positive correlation between ‘subjective’ time estimation (an overestimation) and time experience (the subjects felt that time passed by very slowly), our findings both in study 1 and study 2 showed no effect of depression on ‘subjective’ time estimation, although the depressed patients felt that time passed by very slowly. However, our findings here are in accordance with Mezey & Cohen (1961), and Lehmann (1967). They found that depression is associated with a slowing down of the experience of time, but that time estimation, measured both with the verbal, production, and reproduction methods, was unimpaired. In study 1, we found no difference between endogenous and non-endogenous depression, neither on time estimation nor on time experience, and these findings were reproduced in study 2. On the other hand, in study 2 we could demonstrate that the slowing down of the experience of time paralleled the severity of depression measured by the use of rating scales. Furthermore, our item analysis showed that eleven items on Beck’s scale and three items on Hamilton’s scale fuIfiIled the criteria of calibration, ascending monotonicity, and dispersion, when tested in relation to time experience. The eleven items of Beck‘s scale were broadly identical with the twelve items we found valid in measuring the degree of depression which were parallel with the global clinical assessment. And the three items of Hamilton’s scale recurred in the six items we found valid in measuring the degree of depression. The items found valid when tested in relation to time experience are characterized by referring mainly to mood changes, only to a small extent to somatic symptoms, and not at all to changes in the psychomotor activity. As one of the first, Straus (1928) made the distinction between world time and ego time. It was his impression that depressive patients are very sensitive to the conflict which may arise between the immobility of their own emotions and thought and the changes which they see taking place around them in which they no longer play an active part. Using the time sense inventory constructed by Melges & Fougerousse (1966), we found that only a subgroup of the depressive patients had this distinction between world time and ego time, and we could find no convincing correlation to time experience or to the degree of retardation. Neither could we demonstrate any correlation between the temporal perspective and time experience. From our findings, therefore, we must conclude, that when the depressed patient tells us that “he is very sad and unhappy”, and when he tells that “time passes by very slowly”, he is trying to communicate the same or a similar experience - in two different frames of reference. ACKNOWLEDGMENT
Thanks are due to Jbrgen Nyboe, Rigshospitalet, Copenhagen, for statistical assistance.
50 REFERENCES Ansari, A . R., & R . A . Bradley (1960): Rank-sum tests for dispersion. Ann. Math. Statist. 31, 1174-1189. Bech, P., L . Rafaelsen & 0. J . Rafaelsen (1973): Cannabis and alcohol: effects on estimation of time and distance. Psychopharmacologia (Berl.) 32, 373-381. Bech, P., L. Rafaelsen & 0. J . Rafaelsen (1974): Cannabis: A psychopharmacological review. Dan. med. Bull. 21, 106-120. Bech, P., L . F . Gram, E. Dein, 0. Jacobsen, J . Vitger & T . G . Bolwig (1975): Quantitative rating of depressive states. Correlation between clinical assessment, self-rating scale (Beck), and objective rating scale (Hamilton). Acta psychiat. scand. In press. Beck, A . T., C . H . Ward, M . Mendelson, J . Mock & J . Erbaugh (1961): An inventory for measuring depression. Arch. gen. Psychiat. 4, 561-571. Bouchard, R . (1926): Sur l'tvaluation du temps dans certains troubles mentaux. Vigot FrBres, Paris. Dilling, C. A., & A . 1. Rabin (1967): Temporal experience in depressive states and schizophrenia. J. cons. Psychol. 31, 604-608. Gebsattel, V . E. von (1928): Zeitbezogenes Zwangsdenken in der Melancholie. Nervenartz I, 275-287. Giehm, G . von (193 1): Experimentell-psychologische Untersuchungen der Apperzeption des Zeitsinns bei Geisteskranken. Arch. Psychiat. Nervenkr. 95, 330-335. Hamilton, M . (1960): A rating scale for depression. J. Neurol. Neurosurg. Psychiat. 23, 56-62. Kloos, G . (1938): Storungen des Zeiterlebens in der endogenen Depression. Nervenartz 11, 225-244. Lehmann, H . E. (1967): Time and psychopathology. Ann. N. Y. Acad. Sci. 138, 798821. Lewis, A . (1931): The experience of time in mental disorder. Proc. roy. SOC.Med. 25, 61 1-620. Melges, F. T., & C . E. Fougerousse (1966): Time sense, emotions, and acute mental illness. J. psychiat. Res. 4, 127-140. Mezey, A . G., & S . 1. Cohen (1961): The effect of depressive illness on time judgment and time experience. J. Neurol. Neurosurg. Psychiat. 24,269-270. Rafaelsen, 0. J., P. Bech, J . Christiansen, H . Christrup, J . Nyboe & L . Rafaelsen (1973: Cannabis and alcohol: effect on simultated car driving. Science 173, 920923. Schneemann, K . von (1962): Bemerkungen zum Problem der Zeitstorung in endogenen Depressionen unter Berucksichtigung der Dependenzenlehre von Nicolai Hartmann. Confin. psychiat. (Basel) 5, 37-57. Siegel, S . (1956): Nonparametric statistics. McGraw-Hill, New York. Straus, E. (1928): Das Zeiterlebnis in der qdogenen Depression und in der psychopathischen Verstimmung. Mschr. Psychiat. Neurol. 68, 640-656.
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Received June 18. 1974
Per Bech, M.D. Psychochemistry Institute Rigshospitalet 9 Blegdamsvej DK 2 1 0 Copenhagen Denmark
