The Agentic Self and Personality Changes in Parkinson s Disease

I have been arguing that PD is characterized by weak activation of the neural networks, the striatal-DLPFC/frontopolar cortex, that support the agentic self, the self that identifies, values, formulates plans, makes decisions, initiates actions, and acts. Because the dorsal prefrontal systems normally regulate and inhibit ventral, OF, and limbic systems, the weak activation in striatal/prefrontal circuits in turn leads to hyperactivity in various limbic, amygdalar, and OF circuits. The combination of dorsal prefrontal hypoactivation and ventral prefrontal/limbic hyperactivation contributes to all the neuropsychiatric disorders of PD. In addition, the system imbalances also lead to some characteristic personality traits of PD. These characteristic traits contribute to neuropsychiatric symptomatology as well, so it will be necessary to review them in some detail. The characteristic personality alterations of PD are expected under the theory I have been presenting here. A weak agentic self system and a resultant hyperactive amygdalar and limbic/OF system should yield a personality profile of low novelty seeking (due to weak agency), high harm avoidance, depressive affect, and high anxiety levels (due to hyperactivity in amygdalar circuits).

One of the fascinating things about personality characteristics of PD is that there is fairly good evidence that the personality can be recognized decades before the onset of the motor symptoms of PD. This evidence for a premorbid personality of PD as well as similar findings with respect to depressive and anxious affect appearing decades before the motor problems appear suggest that the illness really begins in forebrain centers rather than in the brain stem or rather that forebrain centers are implicated along with brain-stem pathology right from the beginning of the disease process. Whatever the merits of this conjecture, there is now no question but that there are certain personality traits that are characteristic of someone with parkinsonism. It will be my claim that these personality traits are due to the weak activation of the agentic self system. I turn now to a review of the evidence for all these claims.

Evidence for a Premorbid Personality in PD

Eatough, Kempster, Stern, and Lees (1990) studied personality profiles of young-onset patients with PD. They found that these patients were more cautious, less flexible, more conventional, and stereotyped in thought. Hubble and Koller (1995) studied 35 PD patients and 35 controls with a personality inventory. The investigators asked the spouses of the PD patients to complete the adapted personality inventory on the personalities of their spouses for the period 5 years prior to disease onset and then for the current period. The control spouses completed the personality period for 10 years prior and currently. PD patients were found to be "less talkative" and "flexible" and more "generous," "even-tempered," and "cautious" before the onset of their motor symptoms. The results of Mendelsohn, Dakof, and Skaff's (1995) (based on patient and caregiver recollections of premorbid personality traits) are also consistent with the claim of an introverted premorbid personality type. Glosser et al. (1995) asked relatives of 29 patients with PD to complete the extensive personality inventory, the NEO ("neuroticism," "extraversion," and "openness to experience"; the NEO also measures "agreeableness" and "conscientiousness"), on the patients for the period when patients were in their thirties and for the current period. They also asked a group of relatives of patients with AD to do this task as well. Whereas there was evidence for a premorbid personality type among both patient groups, the premorbid traits were very similar so the authors argued against a distinctive premorbid PD personality. Bower et al. (2010) collated data on 6,822 healthy subjects who were followed over four decades as part of a longitudinal Mayo Clinic study on personality and aging. All of these participants had been given a version of the Minnesota Multiphasic Personality Inventory (MMPI) at the beginning of the study. Two hundred twenty-seven of these subjects developed parkinsonism (156 developed PD). When the authors assessed the extent to which baseline MMPI scores were related to PD onset, it was found that an anxious personality profile was associated with an increased risk of PD [hazard ratio (HR), 1.63; 95% confidence interval (CI), 1.16-2.27]. A pessimistic personality trait was also associated with an increased risk of PD but only in men. A depressive profile was not related to PD onset. When anxiety, pessimism, and depressiveness were combined into a single neuroticism scale, this scale, too, predicted later par-kinsonism. Notably, significant effects were obtained for this scale even when the

MMPI was administered early in life many decades earlier (with subjects aged 20-39 years old). Thus, the personality profile that best predicted PD onset some five decades later was an "anxious" and "neurotic" profile that was obtained when these people were young adults. Several case-control or cohort studies (reviewed in Savica, Rocca, & Ahlskog, 2010) have suggested that anxiety may be one of the earliest manifestations of PD even when analyses are restricted to 20 or more years before PD onset. In summary, anxiety and neuroticism may predate motor symptoms of PD by more than 20 years. This personality profile may, therefore, be one of the earliest biomarkers for the disease currently known. REM sleep behavior disorder (RBD) can precede PD onset, but typically, it does not appear until 5 or 10 years before onset. The same is true with other potential clinical biomarkers such as constipation. Thus, the premorbid personality of PD may be the earliest clinical biomarker for risk of the disease that we have.

This latter result raises the issue of whether genetics plays a role in creating a vulnerability to both an anxious personality style and ultimate PD. Twin studies might be able to shed some light on this question, but I could identify only three such studies. Duvoisin, Eldridge, Williams, Nutt, and Calne (1981) studied 12 mono-zygotic twin pairs discordant for PD. The affected twins were found to be more nervous and introverted than their twins. Ward et al. (1984) studied 20 twin pairs discordant for PD and found (based on retrospective recall by them and their relatives) that the affected twin at age 8 was less usually the leader and more self-controlled; 10 years before onset of PD, the affected twin was still less usually the leader, more nervous, and less adventurous than the other twin. Heberlein, Ludin, Scholz, and Vieregge (1998) studied 15 German-speaking twin pairs discordant for PD; 6 monozygotic (MZ) twin pairs (4 men); 9 dizygotic (DZ) twin pairs (5 men); and a group of controls. Twins with PD scored lower than controls and their twin counterparts in "achievement orientation" and "extraversion," and they scored higher in "inhibitedness," "somatic complaints," and "emotionality."

The PD Personality Persists Through the Course of the Illness

Many clinicians who specialize in PD have suggested that PD may be associated with a specific social style or personality type—a personality profile that cannot be due merely to reactions to chronic disease. Notably, this personality type is consistent with the premorbid personality profile ascribed to PD patients. This parkinso-nian personality has been described as socially withdrawn, rigid, punctilious, serious, stoic, introverted, and uninterested in others. The first controlled study of personality features of PD that I could find in the English language literature was by Booth

(1948). Before the late 1940s, the literature on nonmotor and personality symptoms of PD was largely anecdotal and observational. In addition, these observations of patients with the shaking palsy may have included all kinds of variants of parkin-sonian-type disorders rather than the disorder we call PD today. Despite the uncontrolled nature of the observations made of people with parkinsonism, it is a remarkable fact that certain trends emerge in these clinical observations (table 6.1). The psychoanalysts tended to note that the patients had a weak ego but were deeply aggressive in their dreams; the non-Freudian psychiatrists pointed to the high intelligence, rigid moralism, and industriousness of many of their patients, and the neurologists tended to find similar traits in their patients.

Booth (1948) used clinical interviews and the Rorschach method to study personality changes in 66 patients with various types of parkinsonism and a group of patients with arterial hypertension as controls. He also claimed to have examined handwriting specimens of 16 patients produced before the onset of parkinsonism, but he quotes another author for the source of these data. In any case, Booth claimed that the parkinsonian personality is characterized by an urge toward action, expressed through motor activity (thus, the tremor) and through industriousness; striving for independence, authority, and success within a rigid, usually moralistic, behavior pattern. Booth also noted that many of his patients suffered from marked claustrophobia—an anxiety disorder. We will see that anxiety disorders are a constant of PD both premorbidly and throughout the course of the disease.

Prichard, Schwab, and Tillmann (1951) examined 100 patients with various forms of parkinsonism and concluded that their personalities fell into one of the following groups: group A (48 patients) were stable, easy-going personalities; group B (33 patients) were suggestible and dependent personalities; and group C (19 patients) were driving, restless, and assertive. He argued that these differing personality types responded differentially to medical treatments with groups A and B responding favorably to most medications and only 37% of group C responding favorably to treatment. This observation of Prichard and colleagues (1951) that patients with a distinct personality profile (group C) has not been adequately followed up. Prichard and his colleagues were later to claim a fourth group of PD patients existed that evidenced frank psychopathology.

Machover (1957) studied the responses to Rorschach figures of 42 patients with various form of parkinsonism. He argued that personality changes depended on duration of the disease and so he compared responses of patients who had the disease for a short period with patients who had the disease for a long period of time. Across both groups, he claimed to have found evidence for cognitive interference, dependence, affective instability, inertia, and passivity. The groups differed in the amount of constriction, rigidity, and inertia they expressed in their responses with greater amounts of these responses occurring in the long-duration group.

Our research team has also documented alterations in the PD self and personality relative to both healthy age-matched controls and to other patients with chronic neurologic impairments such as low back pain, aphasia, AD, and cardiovascular disease (McNamara & Durso, 2000, 2003; McNamara, Durso, & Brown, 2003; McNamara, Durso, & Harris, 2006, 2007; McNamara, McLaren, & Durso, 2007; McNamara, Obler, Au, Durso, & Albert, 1992). Using a sentence stem-completion task that allows one to classify respondents into one of several personality profiles, we (McNamara et al., 2003) found that whereas 12.84% of PD responses were classified as "impulsive/self-protective," only 7.5% of age-matched control responses were so classified. The bulk of PD responses were classified as "socially conformist" (36%) or transitional between "conformism" and "conscientious" (28%). The corresponding percentages for controls were 41% "conformist" and 32% "transitional." A conformist social style implies a reduced investment in a more independent and autonomous style. This reduction in autonomy, of course, should not be surprising in a progressive disorder like PD. Analysis of PD responses as a function of Hoehn-Yahr disease stage revealed that patients classified into stage 3 produced a greater percentage (an increase of 14%) of conformity responses compared with that of stage 2 patients and, conversely, fewer "conscientious" responses (decrease of 16%) than that of stage 2 patients, suggesting a shift toward a conformist sense of self as the disease progresses. Paradoxically, while the disease promotes a greater and greater reliance on others, it simultaneously undermines the ability of the patient to understand the motives and intentions of others. This latter problem may then lead to an overall inclination to withdraw from others.

A number of studies of the self and personality in PD have investigated the tendency to withdraw from interactions with others. A number of these studies have used Cloninger's (1987) Tri-dimensional Personality Questionnaire (TPQ) to assess three dimensions of personality that characterize various styles of social actions and interaction. These fundamental aspects of the agentic self are called novelty seeking (NS), harm avoidance (HA), and reward dependences Most of these studies have documented reduced novelty-seeking responses and high harm-avoidance profiles in PD patients (Kaasinen et al., 2001; Mathias, 2003; McNamara, Durso, & Harris, 2007; McNamara, McLaren, & Durso, 2007; Menza, Golbe, Cody, & Forman, 1993;

A summary of previous research examining personality in PD divided into premorbid, current, and twin studies

Author and Date

Location

Mean Age Mean PD

Population Years Years Hoehn-Yahr

Studied (Range) (Range) Stage (Range)

Medication Information

Control Group Studied

Premorbid Personality

Booth, 1948 USA and Germany

66 mixed parkinsonism patients including encephalitic parkinsonism

(46 males)

Patients with arterial hypertension

Eatough et al., 1990

Menza et al., 1990

England

Brunswick, NJ

Young-onset PD patients (number of each sex not given)

20 PD patients (8 males)

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