Dorien Bangma

GENERAL DISCUSSION AND CONCLUSION | 221 several tests is recommended. Recently, researchers presented a shorter version of the FCAI including 20 out of 38 items with sufficient reliability in both brain injured patients and healthy controls (Sunderaraman et al., 2018, 2020). Other psychometric properties of this short 20-item version, however, still need to be examined (Sunderaraman et al., 2018). A third reason, and perhaps the most important reason, for why our FDM test battery cannot yet be used in clinical practice is that the psychometric properties of these tests and questionnaires also need further investigation. The convergent validity of the FDM test battery could not be evaluated since no comparable FDM tests or questionnaires are available. Most FDM tests that were previously developed (see chapter 4 or Engel et al. (2016) for an overview) are not easily accessible or not suitable for the populations of interest. Furthermore, despite the finding that most cognitive functions showed no or only relatively weak correlations with the FDM tests and questionnaires, some cognitive functions were moderately correlated to FDM tests and questionnaires and cognition was consistently found to play a role in FDM capability problems ( chapters 3, 4 and 7 ). Further examination of the divergent validity of the FDM test battery is therefore required. Also, the criterion and ecological validity of the FDM test battery has not been evaluated yet. This makes it difficult to predict everyday life functioning based on the current FDM tests and questionnaires. The evaluation of the relation between FDM in everyday life, including the personal financial situation of an individual (e.g., financial problems such as debts and poverty), and the tests and questionnaires included in the FDM test battery, would provide more insight in the ecological validity of the FDM test battery. Furthermore, the comparison of financially competent and financially incompetent individuals, as determined by an independent lawyer and/or physician, can provide valuable information about the predictive value of the FDM tests and questionnaires (i.e., sensitivity and specificity of the FDM test battery). A major problem in this context, however, is that there is no golden standard for when a person can be considered financially competent or incompetent. In addition, research on medical decision-making found that clinicians are not well able to estimate a person’s competency to make adequate and deliberate medical decisions (Sessums et al., 2011). Nevertheless, the development of the current FDM test battery is an important step forward in the development of a test battery for clinical practice. The FDM test battery evaluates not only financial competence, but also the financial performance and contextual factors of an individual. With this, the FDM test battery is an important improvement in FDM research since it meets the recommendation to investigate FDM capability in a broad and extensive manner (Appelbaum et al., 2016; Engel et al., 2016). FDM capability is, however, a very broad and difficult to define concept. It is therefore conceivable that not all aspects of financial competence and financial performance are covered with the current FDM tests and questionnaires. Also, more research is needed with regard to the contextual factors related to FDM capability. All these limitations need to be taken into account when interpreting the results of present thesis. Nevertheless, our pioneering research adds valuable information to contemporary FDM research in patients with NDDs and ADHD and provides important suggestions for future research.