The Frontotemporal Syndrome in Amyotrophic Lateral Sclerosis An
Total Page:16
File Type:pdf, Size:1020Kb
The frontotemporal syndrome in amyotrophic lateral sclerosis An interim analysis for a new cognitive screening instrument The aim of this study is to provide an interim analysis, evaluating the diagnostic accuracy and the psychometric qualities of the ALS-FTD-Cog. The ALS-FTD-Cog is a screening instrument, designed to detect cognitive impairment associated with Amyotrophic Lateral Sclerosis (ALS). This cognitive impairment (in combination with behavioural impairment) is known as the Frontotemporal Syndrome (FTS) and occurs in 30-50% of ALS patients. 70 ALS-patients, 35 healthy control participants and fourteen patients with frontotemporal dementia (positive control participants) participated in this study. The outcomes of the ALS-FTD-Cog were compared with a reference standard; a full neuropsychological investigation. In our sample, 14 ALS patients (21%) had FTS. The ALS-FTD-Cog identified these patients with 77% sensitivity and 80% specificity. The reliability varies from acceptable (.7) when calculated in all participants to very low (.2) when calculated in only the ALS patient group. When measured in all subjects, a principal component analysis shows that the ALS-FTD-Cog is a unidimensional measure. However, in only ALS patients the screening outcomes cluster together in a more ambiguous way, suggesting two subscales with low (.3 and .4) reliability. It is important to emphasize that this is an interim analysis, probably lacking the statistical power to draw clear conclusions about the diagnostic accuracy of the ALS-FTD-Cog. However, this study thoroughly analyses the current test outcomes, and identifies important areas for further research concerning the ALS-FTD-Cog. The main objective is not only enhancing the quality of care for FTS patients but also gain a more thorough understanding of the underlying processes in ALS. Name: Anoek Appelboom Supervisor (daily): Rosanne Govaarts Supervisor (AMC): Ben Schmand Word count: 4250 10-07-2016 Contents Introduction P. 3 Methods P. 6 Results P. 11 Conclusion and discussion P. 16 References P. 19 2 Introduction Traditionally, amyotrophic lateral sclerosis (ALS) has been described as a motor neuron disease, selectively targeting the primary motor neuron in the central and peripheral nervous system and causing motor symptoms throughout the body. However, as pointed out by Strong et al. in 1999, a more accurate definition is one of a “multisystem disease”, causing cognitive and behavioural impairment besides the “classic” motor impairment. This cognitive and behavioural impairment is known as the frontotemporal syndrome (FTS), and is caused by frontotemporal lobar degeneration, typically found in frontotemporal dementia (FTD) (Lomen-Hoerth C, Anderson T, 2002; Strong et al., 2009). FTS develops in 30-50% of ALS patients (Beeldman et al., 2015; Montuschi et al., 2014; J. Phukan et al., 2012). In 5-15% of the ALS patients, the symptoms become more severe and meet the criteria of FTD, mostly the behavioural variant (Montuschi et al., 2014; Phukan et al., 2012; Ringholz et al., 2005). A recent meta-analysis showed that the cognitive profile of ALS patients is characterized by deficits in fluency, language, social cognition, executive functions and verbal memory (Beeldman et al., 2015). Possible behavioural changes are apathy or impulsivity, loss of insight, social disinhibition and hyperorality (Grossman, Woolley-Levine, Bradley, & Miller, 2007) FTS has an adverse effect in the patient as well as its environment. However, early detection of FTS may be a challenge, as there are individual differences in how the disease progresses, leading to different presentations of ALS and FTS (Rowland & Shneider, 2001). FTS in ALS patients is associated with shorter survival time, this may be due to biological factors or to the cognitive and behavioural symptoms of FTS, resulting in a decreased adherence to therapeutic interventions or life-prolonging therapies, like non-invasive ventilation. Furthermore, it may negatively influence quality of life of partners and caregivers (Merrilees, Klapper, Murphy, Lomen- Hoerth, & Miller, 2010; Olney et al., 2005). In order to provide a common framework and guidelines for discussing and evaluating 3 FTS, Strong et al. stated that ALS patients are suspected to have mild FTS when they score one standard deviation below the normal mean on an executive measure (Strong et al., 2009). These consensus criteria emphasize the role of executive tests. However, later research shows that it is also possible for clinically distinct FTS patients to be executively intact but fall short on other cognitive domains (Phukan et al., 2012). Cognitive measures that are used nowadays may vary from a full neuropsychological assessment to the administration of a verbal fluency task only (Abrahams, Newton, Niven, Foley, & Bak, 2014). A neuropsychological assessment is time consuming and it may be too fatiguing for some patients, whereas the use of one fluency task leaves out other important cognitive domains. (Lomen-Hoerth et al., 2003; Phukan et al., 2012). Newly developed alternatives are short (10 min) screening instruments, providing a quick scan for multiple cognitive domains (Abrahams et al., 2014; Floris et al., 2012; Woolley et al., 2010). These instruments are useful, but normative data lack the extensive norm groups that are necessary for valid clinical decisions. Also, an instrument that provides a more thorough evaluation of cognitive performance is currently not available. Given the abovementioned shortcomings of currently available cognitive assessments, a new screening instrument, the ALS-FTD-Cog, is under development at the Academic Medical Centre in Amsterdam. It consists of parallel versions of well-known and validated neuropsychological tests, raising the face validity of the screening instrument. The selection of the tests is based on the consensus criteria stated by Strong et al. (2009) and previous research (Beeldman et al., 2015; Phukan et al., 2012), selectively targeting the cognitive deficits of FTS; language, social cognition, executive functioning and memory. Compared to a neuropsychological assessment, it is designed to be faster and more suitable for bedside testing. Furthermore, the tests are not affected by (or control for) impairment caused by ALS, such as muscle weakness and slowness or loss of speech. 4 The aim of this study is to provide an interim analysis, evaluating the diagnostic accuracy and the psychometric qualities of the ALS-FTD-Cog. It is important to note that the emphasis lies on developing a valid and reliable screening instrument. This is investigated in healthy control participants, ALS and FTD patients, by comparing the outcomes the ALS-FTD-Cog to the golden standard, i.e. an extensive neuropsychological assessment. 5 Methods Participants Patients were recruited from the Dutch ALS centre (an expertise centre, based in the Academic Medical Centre and the University Medical Centre Utrecht). To participate in the study, patients had to meet the following inclusion criteria: (a) diagnosis of sporadic or familial ALS, in terms of the El Escorial criteria; possible, (probable-) laboratory supported or definite ALS (Brooks, Miller, Swash, & Munsat, 2000), (b) with a disease duration (time since symptom onset) of less than 12 months, (c) patients had to be 18 years or older, (d) have a fluent knowledge of the Dutch language, and (e) have a proxy (this might be partner, family member or close friend) who spoke Dutch and was willing to fill in several questionnaires. Excluded were patients who (a) were considered incompetent (e.g. in case of unaccountability for consent) by their treating physicians or (b) had other neurological or psychiatric conditions that might affect cognitive functioning. FTD patients were recruited from the Dutch Alzheimer centre, based in the VU University Medical Centre. Healthy control participants were recruited from the social environment of the patients. Participation was on voluntary basis. The medical ethical committee approved the study. Written informed consent was obtained from all participants at inclusion. Participants received both the neuropsychological assessment and the screening with a two week interval, this interval was chosen to limit both practice effects in parallel tests and effects of possible cognitive degeneration between the two test moments. To further avoid practice effects, the order of the tests was counterbalanced. In consultation with the patient, half of the participants was assigned to complete the neuropsychological assessment before the screening and vice versa. The neuropsychological assessment (±1.5 – 2 hours) was conducted at a hospital nearby the patient. To minimize strain on the patient, the screening (± 30 minutes) was conducted during a home visit. All tests were conducted by formally trained test assistants or neuropsychologists. The ALS-FTD- 6 Cog and the neuropsychological assessment were never administered by the same person to limit the effect of observer bias. Materials The neuropsychological assessment was an extended test battery, based on the cognitive domains and tests that proved sensitive for FTS in previous literature (Table 1) (Strong et al., 2009). The selected subtests were not affected by, or are corrected for, motor impairment and dysarthria. Therefore, this battery was considered similar to the neuropsychological assessment administered on ALS patients in clinical practice. The ALS-FTD-Cog consisted of the five following subtests: The Faux-Pas Recognition