Dorien Bangma

60 | CHAPTER 4 living with an NDD can make financial decisions, performance-based FDM tests need to be used. The aim of the present study is to provide a comprehensive overview and meta-analysis of studies evaluating FDM in people living with an NDD. For this, an evaluation of the reliability of performance-based tests to consistently identify FDM difficulties in people living with an NDD compared to healthy controls will be conducted. If possible, the performances on tests of FDM between groups with different NDDs will also be compared. Furthermore, the influence of disease severity and disease progression on FDM will be explored as well as the associations between FDM and performances on standard measures of cognition and demographic variables (i.e., age, sex and education). NDDs are a heterogeneous group of disorders and the NDDs that are considered in the present systematic review and meta-analysis were selected based on prevalence rates. Since it is beyond the scope of this systematic review to describe all NDDs in detail, a short description of the NDDs that are considered in the present study will be provided. The first disorder that is considered is AD. AD is the most common NDD (Reitz et al., 2011) and is typically characterized by a progressive loss of functional independence and a gradual decline of memory. In addition, cognitive domains such as executive and visuospatial functions are often affected in people living with AD. Mild cognitive impairment (MCI) is often considered to be a prodromal stage of AD (or of other dementia's) and was, therefore, also taken into account in the present systematic review. MCI is diagnosed when there are concerns about a change in cognition, when impairments are present in one or more domains of cognition, while there is a preservation of functional independence and when the cognitive impairments are sufficiently mild that the person is not demented (Albert et al., 2011). The second most common NDD is PD which was, therefore, also taken into account in the present systematic review. PD also has a progressive decline and the diagnosis is based on the presence of motor symptoms such as rigidity, bradykinesia and tremor. Non-motor symptoms, including cognitive impairment in the domains of executive functions, attention, and visuospatial functions, are, however, also often present which can result in PD dementia (PDD) as the disease progresses (Hely et al., 2008; Litvan et al., 2011). Another common type of NDD that is closely related to PD is dementia with Lewy bodies. Dementia with Lewy bodies is also characterized by impairments in executive functions, attention, and visuospatial functions, resulting in dementia, and by motor symptoms such as bradykinesia, rigidity and tremor. However, within the context of dementia with Lewy bodies, and in contrast to PDD, dementia precedes or occurs simultaneously with the occurrence of motor symptoms (McKeith et al., 2005). Frontotemporal dementia (FTD) refers to a group of conditions which are predominately characterized by neurodegeneration of the frontal and temporal cortices. FTD is a common cause of dementia under the age of 65. The two core conditions within the context of FTD are the behavioral variant of FTD and primary progressive aphasia. The behavioral variant of FTD is characterized by changes in behavior, personality and emotion and by impairments in executive function and social cognition (Rascovsky et al., 2011), while impairments in language are the hallmark of primary progressive aphasia (Gorno-Tempini et al., 2011). Since there is a significant clinical overlap between the behavioral variant of FTD and amyotrophic lateral sclerosis (Lomen-Hoerth, 2011;