Harm avoidance and self-directedness traits linked to BD vulnerability
MedWire News: Results from a Brazilian study suggest that the harm-avoidance (HA) temperament and the self-directedness (SD) character trait are associated with increased vulnerability to bipolar disorder (BD).
"Most of the studies comparing the Temperament and Character Inventory (TCI) results between patients with BD and healthy controls have demonstrated that the patients present higher scores on novelty seeking (NS), HA, and self-transcendence (ST), whereas their scores are lower on SD and cooperativeness (CO)," observe Karla Mathias de Almeida (University of São Paulo School of Medicine) and team.
But they add that "it is unclear whether, and to what extent, those associations reflect a scarring effect of the affective episodes or whether the differences existed before the onset of the first symptoms and represent vulnerability factors for BD."
To investigate further, the researchers studied 67 euthymic patients with type I BD, 67 of their siblings without BD, and 70 mentally healthy individuals (controls). Of the 67 siblings, 35 (52.0%) had been diagnosed with at least one lifetime Axis I disorder other than BD. There were no significant differences among the groups in terms of age, gender, and socioeconomic status.
All of the participants completed the TCI, which is a self-report questionnaire that includes 240 true-false items designed to measure individual differences in seven dimensions of temperament and character.
The researchers found that BD patients had significantly higher TCI scores for HA, NS, and ST than controls, at 20.15 versus 9.26, 20.13 versus 17.14, and 18.69 versus 12.74, respectively.
By contrast, BD patients had significantly lower TCI scores for SD and CO than controls, at 27.70 versus 37.67, and 30.21 versus 33.30, respectively.
Siblings of the BD patients, as a whole, also had significantly higher TCI scores for HA (16.76) and lower scores for SD (32.66) than controls.
In addition, siblings with at least one lifetime Axis I disorder had significantly higher TCI scores for HA (19.60) compared with both mentally healthy siblings (13.66) and controls.
"Our results suggest that higher scores on HA and lower scores on SD might represent vulnerability markers for BD," conclude the researchers in the journal Bipolar Disorders.
They add: "HA is of special interest because it was elevated even among siblings without a history of Axis I disorders.
"Prospective studies to investigate whether HA is truly a vulnerability trait for BD are warranted."
By Mark Cowen