Trait shyness in the elderly: evidence for an association with Parkinson's disease in family members and biochemical correlates.

The emergence of potential treatments to slow the progression of idiopathic Parkinson's disease (PD) has increased the need for early identification of persons at risk. Although considered controversial, some prior studies indicate that PD patients may have premorbid histories of greater trait introversion or shyness as well as increased rates of disorders associated with shyness (e.g., anxiety, affective disorders, and irritable bowel syndrome). Essential features of trait shyness include (a) inhibited and avoidant behaviors and (b) physiological hyperreactivity to the novel or unfamiliar. In parallel, (a) depression in PD patients is associated with increased harm avoidance (a possible serotonergic function), and (b) PD patients have premorbid and comorbid decreases in novelty-seeking (a possible dopaminergic function). Taken together, previous research suggests the following hypotheses: (1) given evidence for marked heritability of shyness, shy elderly should report higher rates of PD in their family members than would nonshy elderly; and (2) shy elderly without PD should exhibit psychological and biologic characteristics similar to those reported in PD. Two groups, representing the top 27% (n = 37) and bottom 31% (n = 43) of scores on a standardized shyness scale, were drawn from a larger cohort of 138 older adults (ages 50-90) living in an active retirement community. Seventeen percent of the shy versus 2% of the nonshy reported PD in a family member or self (P < .05). Shy elderly were significantly more anxious (P < .01) and depressed (P < .05) than were the nonshy.(ABSTRACT TRUNCATED AT 250 WORDS)