In follow-up questionnaire 1C, adult Lifelines participants were asked in how far they possess a Type D personality ¹⁾ (section: mental health).
Note that personality traits were also assessed in Lifelines using the ASI, the GAS, and the NEO questionnaires.
Moreover, various personality traits (hostility, reward sensitivity) were assessed in the context of an additional questionnaire on ADHD.

Individuals with a Type D personality have the tendency to experience increased negative emotions across time and situations and tend not to share these emotions with others, because of fear of rejection or disapproval. The letter D stands for distressed.
Some early studies found that coronary artery disease (CAD) patients with a Type D personality have a worse prognosis following a myocardial infarction (MI) as compared to patients without a Type D personality.
However, not all studies with a similar research question could replicate these findings. Consequently, some researchers have questioned the influence of Type D personality on heart disease outcomes ²⁾.

The Type-D questionnaire used in Lifelines contains 14 items from the DS14³⁾, which includes seven items that refer to negative affectivity (items 2, 4, 5, 7, 9, 12, 13), and seven items that refer to social inhibition (items 1, 3, 6, 8, 10, 11, 14).
The Type-D quesitonnaire in Lifelines contains 6 additional items (15-21).
Participants were asked to rate how well the statements describe their personality on a 5-point Likert scale ranging from 0 (false) to 4 (true). People who score 10 points or more on the DS14 are classified as Type D.