Depression: a primary symptom of Parkinson Disease?

Depression: A Primary Symptom of Parkinson Disease?

One of the most common neurological conditions present in geriatric clients who seek rehabilitation services is Parkinson disease. While there appears to be good agreement on the nature of its primary physical symptomatology -- i.e., tremor, rigidity, and bradykinesia -- this is not the case for its primary psychological symptomatology (Dakof & Mendelsohn, 1986). There is considerable disagreement about whether chronic depression occurs frequently enough to be considered a primary symptom of the disease, and if it does, whether its cause is mainly biochemical or psychosocial. A high incidence of chronic depression among persons who have this disease -- regardless of whether its etiology were physiological or psychological--obviously would impact upon the activities of those responsible for planning and assessing rehabilitation services for such persons.

Traditionally, depression had been regarded as being as much a primary symptom of Parkinson disease as tremor, rigidity, and bradykinesia (Dakof and Mendelsohn, 1986; Gotham, Brown, and Marsden, 1986; Horn, 1974; Robins, 1976; Santamaria, Tolosa, and Valles, 1986). This may have been due, in part, to the fact that persons who are depressed and those who have Parkinson disease tend to share the following symptoms: slowness in movement, stooped posture, blank facial expression, sleep disturbances, and slowness in cognitive functioning. The findings of several recent studies suggest that chronic depression is not a primary symptom of Parkinson disease--i.e., they suggest that the majority of persons who have the disease are not chronically depressed (Dakof and Mendelsohn, 1986; Santamaria, Tolosa, and Valles, 1986). A study is reported in this paper the findings of which are consistent with this conclusion.

Method

Fifty-two persons who had Parkinson disease, who were members of the Wisconsin Parkinson Association, completed a semantic differential task (Osgood, Suci, & Tannenbaum, 1957). The majority of the participants were male (70 percent) and married (81 percent). The participants ranged in age from 45 to 83 years (mean - 68 years) and the mean length of time they had had Parkinson disease was eight years (range 2 to 25 years). The majority (65 percent) of them were retired.

Participants were instructed to rate themselves on each of 81 seven-point, bipolar adjectival scales with regard to how well the adjectives that defined the scale described them. The semantic differential used (Silverman, 1985, pp. 258-259) was designed for eliciting stereotypes of persons who had communicative disorders. We decided to use this semantic differential because it included a depressed/happy scale, and since it contained so many scales, participants would be unlikely to infer the purpose of our study (i.e., to determine whether the majority of persons with Parkinson disease are depressed) from examining it. Each scale was presented in this form: depressed - - - - - happy.

The semantic differential task was administered using a standard set of instructions (Silverman, 1985, pp. 256-257).

Results

Three percentages were computed for each scale: the percentage of participants whose ratings were at one of the two poles (i.e., the percentage who placed a mark on one of the three lines at the right or left side of the scale) and the percentage of participants whose ratings were at the center of the scale. The majority of the participants did not judge themselves to be depressed. Only nine of the 52 (17 percent) revealed by their ratings on the depressed/happy scale that they were depressed: A chi square test (Siegel, 1956) indicated that the probability of this outcome being due to chance is less than 0.01. These data suggest that chronic depression is not experienced by the majority of persons with Parkinson disease who are similar to our subjects and, hence, it is not a primary symptom of Parkinson disease for such persons. There is additional support for this conclusion in the ratings of participants on some of the other scales. Among the adjectives which intuitively do not seem associated with depression that the majority used to describe themselves are the following: mature, lovable, intelligent, secure, unselfish, honest, witty, stable, sociable, friendly, brave, reputable, optimistic, trustworthy, reliable, sane, contented, not frightened, alert, courteous, congenial, industrious, realistic, approachable, having a positive self-concept, independent, confident, competent, happy, organized, sincere, enthusiastic, and kind. The majority of participants did not select any adjectives by their ratings that intuitively would be characteristic of a person who is depressed.

Discussion

The extent to which the finding of this study can be generalized is uncertain. Our "typical" (average) participant was male, married, over 60, had had Parkinson disease for eight years, and belonged to a support group for persons with the disease. Several of these characteristics could have reduced the prevalence of chronic depression in our sample. The findings of a large body of research in psychology and sociology indicates that males in this age group who are married tend to be less likely to be depressed than those who are divorced or widowed. Also, the majority of our participants, since they had had the condition for a number of years, probably had passed through the depression stage of the grieving process. If the average length of time our participants had had the disease had been one year or less, a higher percentage of them probably would have reported being depressed. In addition, our participants all belonged to a support group for persons with the disease. Participation in the activities of such a group should help in coping with the disease which, in turn, would tend to reduce depression associated with an inability to cope. The fact that our findings are similar to those of other recent studies (e.g., Dakof & Mendelsohn) concerning the prevalence of depression in this population suggest that they can at least be generalized to a large subgroup in it.

The fact that chronic depression does not appear to be a primary symptom of Parkinson disease has several implications for rehabilitation professionals. First, it is not safe to assume that persons with this disease who "look" depressed are, in fact, depressed because some of the symptoms that could cause us to assume that they are depressed are also primary motor symptoms of the disease. Second, persons who have recently been diagnosed as having the disease and who frequently experience depression as part of the grieving process can be given hope that their emotional state is likely to improve since the majority of our participants, apparently as a result of learning to cope with the disease, had developed a positive attitude toward life. And third, if the client is a member of the relatively small subgroup who remain chronically depressed (Santamaria, Tolosa, & Valles, 1986), this should not be accepted as a condition about which nothing can be done. Based on the findings of this and other studies, long-term chronic depression is not a primary symptom of Parkinson disease. Participating in a support group, such as the one to which our participants belonged, and learning to cope better with the disease from persons who have been successful in doing so probably would help at least some of these persons to develop a more positive attitude toward life.

Appendix

The scales included on the semantic differential used in this study were the following: afraid--not afraid, mature--immature, unlovable--lovable, speech intelligible--speech unintelligible, intelligent--unintelligent, secure--insecure, natural--unnatural, no sense of humor--sense of humor, speaks rapidly--speaks slowly, unselfish--selfish, dishonest--honest, fluent--disfluent, cautious--rash, witty--dull, speech monotonous--speech not monotonous, stable--unstable, employable--unemployable, unsociable--sociable, loud--soft, old--young, coordinated--uncoordinated, dominant--submissive, speech dysrhythmic--speech rhythmic, speech unpleasant--speech pleasant, hesitant--not hesitant, boring--interesting, unfriendly--friendly, cowardly--brave, confused--orientated, superior--inferior, speech slow--speech fast, reputable--disreputable, optimistic--pessimistic, excitable--calm, handicapped--not handicapped, untrustworthy--trustworthy, relaxed--tense, contrary--agreeable, reliable--unreliable, extrovert--introvert, rich--poor, insane--sane, contented--discontented, soothing--aggravating, not frightened--frightened, not frustrating--frustrating, alert--not alert, speaks poorly speaks well, discourteous--courteous, quarrelsome--congenial, lazy--industrious, deaf--not deaf, emotional--unemotional, realistic--idealistic, approachable--unapproachable, not talkative--talkative, not aggressive--aggressive, weak--strong, positive self-concept--negative self concept, uneducated--educated, deliberate--impulsive, nervous--calm, sensitive--insensitive, able to carry on conversation--unable to carry on conversation, scrupulous--unscrupulous, independent--dependent, masculine--feminine, confident--not confident, frustrated--not frustrated, competent--incompetent, inhibited--uninhibited, depressed--happy, organized--unorganized, accept--reject, isolated--not isolated, comfortable, insincere--sincere, enthusiastic--unenthusiastic, soothing--uncomfortable, kind--cruel, and naive--sophisticated.

References

Dakof, G.A., & Mendelsohn, G.A. (1986). Parkinson's disease: The psychological aspects of a chronic illness. Psychological Bulletin, 99, 375-387. Gotham, A.M., Brown, R.G., & Marsden, C.D. (1986). Depression in Parkinson's disease: A quantitative and qualitative analysis. Journal of Neurology, Neurosurgery, and Psychiatry, 49, 381-389. Horn, S. (1974). Some psychological factors in Parkinsonism. Journal of Neurology, Neurosurgery, and Psychiatry, 37,27-31. Osgood, C.E., Suci, G.J., & Tannenbaum, P.M. (1957). The Measurement of Meaning. Urbana, Illinois: University of Illinois Press. Robins, A.H. (1976). Depression in patients with Parkinsonism. British Journal of Psychiatry, 128, 141-145. Santamaria, J., Tolosa, E., & Valles, A. (1986). Parkinson's disease with depression: A possible subgroup of idiopathic Parkinsonism. Neurology, 36, 1130-1133. Siegel, S. (1956). Nonparametric Statistics for the Behavioral Sciences. New York: McGraw-Hill. Silverman, F.H. (1985). Research Design and Evaluation in Speech-Language Pathology and Audiology (2nd Ed.). Englewood Cliffs, N.J.: Prentice-Hall.