A Cross-sectional population-based investigation into behavioral change in amyotrophic lateral sclerosis: subphenotypes, staging, cognitive predictors, and survival

Objective

Amyotrophic Lateral Sclerosis (ALS) is a clinically heterogeneous neurodegenerative disorder associated with cognitive and behavioral impairment. The primary aim of this study was to identify behavioral subphenotypes in ALS using a custom designed behavioral assessment tool (Beaumont Behavioural Inventory, BBI). Secondary aims were to (1) investigate the predictive nature of cognitive assessment on behavioral change, (2) report the behavioral profile associated with the C9orf72 expansion, (3) categorize behavioral change through disease staging, and (4) to investigate the relationship between cross‐sectional behavioral classification and survival.

Methods

A cross‐sectional population‐based research design was applied to examine behavioral data from ALS patients (n = 317) and healthy controls (n = 66). Patients were screened for the C9orf72 repeat expansion. A subcohort of ALS patients completed an extensive cognitive assessment battery (n = 65), to investigate predictors of behavior change. Principal component analysis (PCA) determined factors associated with altered behavior. Survival data were extracted from the Irish ALS register.

Results

No behavioral changes were reported in 180 patients (57%); 95 patients had mild‐moderate behavioral change (30%); 42 patients met the cut‐off for Clinically Severe Behavioral Change (13%), suggestive of a bvFTD diagnosis. The most frequently endorsed behaviors in ALS were reduced concern for hygiene (36.8%), irritability (36.2%), new unusual habits (33.4%), and increased apathy (31.1%). Five independent factors were identified through factor analysis. Social cognitive performance was predictive of behavior change (P = 0.031), yielding an R² = 0.188. Behavioral categorization (mild/moderate/severe) at the time of assessment was not associated with survival (P = 0.198).

Interpretation

These data imply the presence of distinct subphenotypes of behavioral change in ALS, which most likely reflect subcategories of extramotor network disruption.

Caregivers of patients with amyotrophic lateral sclerosis: investigating quality of life, caregiver burden, service engagement, and patient survival

Few studies in amyotrophic lateral sclerosis (ALS) have profiled disease-specific features of the condition in conjunction with assessment of caregivers' burden, distress, quality of life, and investigated patient survival. Eighty-four ALS patients and their primary caregivers were enrolled. Patients completed ALS-specific measures of physical and cognitive function, while caregivers completed measures of anxiety, depression, caregiver burden, and quality of life. Patient-caregiver dyads were interviewed about their health-service utilisation. Survival data were obtained through the Irish register for ALS. Participants were dichotomised into low/high groups according to the severity of self-reported caregiver burden, based on statistically derived cut-off scores. High-burdened caregivers (n = 43) did not significantly differ from low-burdened caregivers (n = 41) with respect to disease-specific characteristics, i.e., ALSFRS-R, bulbar- or spinal-onset ALS, disease duration, or survival data. However, significant differences were reported on subjective measures of anxiety (p < 0.000), depression (p < 0.001), distress (p < 0.000), and quality of life (p < 0.000). These data demonstrate the limited impact of ALS patient-related variables, i.e., ALSFRS-R and onset, on caregiver burden in ALS, and identify the importance of the psychological composition of caregivers. This study suggests that the subjective experience of individual caregivers is an important factor influencing the severity of experienced caregiver burden.

Identifying behavioural changes in ALS: Validation of the Beaumont Behavioural Inventory (BBI)

OBJECTIVE

Behavioural changes are an important part of amyotrophic lateral sclerosis (ALS). However, most tools do not account for the influence of motor impairment. Furthermore, they do not fully measure the broad range of behavioural changes specific to ALS. This study aimed to develop and validate an ALS specific behavioural inventory, the Beaumont Behavioural Inventory (BBI).

METHODS

The BBI was validated in a cohort of ALS patients (n = 85) and 78 age-, gender-, and education-matched controls. The scale was validated against the Frontal Systems Behaviour Scale (FrSBe) and The Frontal Assessment Battery (FAB) for convergent validity, and against other non-behavioural measures to assess discriminant validity. Reliability was assessed with Cronbach's alpha.

RESULTS

The instrument showed high internal consistency (Cronbach's alpha value =0.891). BBI scores highly correlated with the FrSBe and moderately with the FAB. However, the measure was independent from non-behavioural measures. Using a cut-off score of 7 for mild behavioural changes, the BBI displayed high sensitivity and specificity (87.9% and 78.85%, respectively). The cut-off score for moderate changes, consistent with a diagnosis of ALS-FTD, is set at 22.5, showing 90% sensitivity and 96% specificity.

DISCUSSION

The BBI is a sensitive and specific tool to assess the entire behavioural spectrum of ALS.

Measurement of Social Cognition in Amyotrophic Lateral Sclerosis: A Population Based Study

Background: Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disease. Executive dysfunction is common in patients with ALS, with up to 50% of patients performing within an impaired range. There is evidence that social cognitive deficits associated with ALS are a function of deficits in executive function. The ‘Reading the Mind in the Eyes’ Test is a recognized test of social cognitive function, although the reliability of this instrument remains to be established. Methodology: Patients with ALS (n = 106), and age and IQ matched controls (n = 50) were recruited and asked to perform the Reading the Mind in the Eyes Test as part of an on-going population-based study of cognitive function. ALS patients were sub-stratified based on the presence, and/or extent of executive dysfunction. Results: Cronbach’s Alpha of .73 was observed, indicating good reliability on this measure. Split-half reliability analysis further confirms these findings (p = 0.826). The Reading the Mind in the Eyes test had excellent psychometric properties when discriminating between ALS patients who are cognitively intact, and those who have executive impairment, with an overall medium difficulty. There was a large magnitude significant difference between patients and controls (p< 0.001; η² = .19). Post-hoc analysis revealed that controls performed significantly higher than patients with executive impairment (p< 0.001), and patients with single executive deficits (p = 0.002). Conclusion: Executive dysfunction impacts on social cognitive performance. This study contributes not only to the psychometric knowledge of this measure, but also to the usability, efficacy, and reliability of social cognitive assessment in ALS. Using population-specific normative data, we confirm the Reading the Mind in the Eyes Test is a reliable measure of social cognitive processes in ALS.

Discordant performance on the 'Reading the Mind in the Eyes' Test, based on disease onset in amyotrophic lateral sclerosis

Executive dysfunction is a core feature of amyotrophic lateral sclerosis (ALS) and is associated with brain atrophy in cortical and subcortical regions. Social cognitive deficits may also be a prominent feature of ALS. This study investigated executive, and social cognitive performance, in a population based cohort of patients with ALS, stratified by disease onset. Participants were recruited as part of a population based study investigating cognitive decline in ALS. Patients carrying pathogenic C9orf72 hexanucleotide repeat were excluded. Participants were stratified based on bulbar (n = 20) or spinal (n = 39) disease onset (n = 59). Matched healthy controls were used to generate culturally specific comparative data for within-patient analyses (n = 59). Results showed that ALS patients performed significantly worse than controls on a number of measures of executive function. When sub-stratified by disease onset, there was a significant difference between bulbar- and spinal-onset patients with respect to the 'Reading the Mind in the Eyes' Test scores (p < 0.001). Conversely, standardized scores of executive function did not differ between the patient groups. In conclusion, patients performed significantly worse than matched controls on measures of executive function. Bulbar-onset ALS patients evidenced more social-affective deficits compared to spinal-onset patients, with matched performance on measures of executive function.

Closing the tau loop: the missing tau mutation

Frontotemporal lobar degeneration comprises a group of disorders characterized by behavioural, executive, language impairment and sometimes features of parkinsonism and motor neuron disease. In 1994 we described an Irish-American family with frontotemporal dementia linked to chromosome 17 associated with extensive tau pathology. We named this disinhibition-dementia-parkinsonism-amyotrophy complex. We subsequently identified mutations in the MAPT gene. Eleven MAPT gene splice site stem loop mutations were identified over time except for 5' splice site of exon 10. We recently identified another Irish family with autosomal dominant early amnesia and behavioural change or parkinsonism associated with the 'missing' +15 mutation at the intronic boundary of exon 10. We performed a clinical, neuropsychological and neuroimaging study on the proband and four siblings, including two affected siblings. We sequenced MAPT and performed segregation analysis. We looked for a biological effect of the tau variant by performing real-time polymerase chain reaction analysis of RNA extracted from human embryonic kidney cells transfected with exon trapping constructs. We found a c.915+15A>C exon 10/intron 10 stem loop mutation in all affected subjects but not in the unaffected. The c.915+15A>C variant caused a shift in tau splicing pattern to a predominantly exon 10+ pattern presumably resulting in predominant 4 repeat tau and little 3 repeat tau. This strongly suggests that the c.915+15A>C variant is a mutation and that it causes frontotemporal dementia linked to chromosome 17 in this pedigree by shifting tau transcription and translation to +4 repeat tau. Tau (MAPT) screening should be considered in families where amnesia or atypical parkinsonism coexists with behavioural disturbance early in the disease process. We describe the final missing stem loop tau mutation predicted 15 years ago. Mutations have now been identified at all predicted sites within the 'stem' when the stem-loop model was first proposed and no mutations have been found within the 'loop' region as expected. Therefore we 'close the tau loop' having 'opened the loop' 21 years ago.

Caregiver burden in amyotrophic lateral sclerosis: a cross-sectional investigation of predictors

The objective of the study was to investigate whether cognitive and behavioural impairment in Amyotrophic Lateral Sclerosis (ALS) contributes to caregiver burden, and whether carer burden affects patient outcome. Thirty-three dyads of incident patients with ALS and their primary caregivers (n = 33) completed a series of measures to determine cognitive and behavioural profiles, (patients) and carer burden (carers) to investigate the psychological impact of ALS, and the impact of behavioural change since the onset of ALS. Caregivers were divided into high- and low-burden groups using previously established norms. High burden in carers was associated with significantly higher apathy (p = 0.009), disinhibition (p = 0.005), and executive dysfunction (p = 0.015) in patients. Regression analyses for burden confirmed significant predictors such as change in apathy (r = 0.390, F = 5.19, p = 0.03), disinhibition (r = 0.530, F = 11.32, p = 0.002), and executive dysfunction (r = 0.372, F = 4.66, p = 0.039), with total behaviour change contributing to 31 % of caregiver burden (r = 0.563, F = 4.17, p = 0.015). Total distress as measured by the Hospital Anxiety and Depression Scale was also a significant predictor of caregiver burden, contributing to 38.5 % of variance (r = 0.621, F = 18.79, p < 0.000). Caregiver burden did not affect survival (p = 0.496). Caregiver burden in ALS is modulated by patient's cognitive and behavioural status, but does not significantly impact patient survival.

Grey matter correlates of clinical variables in amyotrophic lateral sclerosis (ALS): a neuroimaging study of ALS motor phenotype heterogeneity and cortical focality

BACKGROUND

Body region of onset and functional disability are key components of disease heterogeneity in amyotrophic lateral sclerosis (ALS).

OBJECTIVES

To evaluate patterns of grey matter pathology in the motor cortex and correlate focal structural changes with functional disability.

METHODS

We conducted a single-centre neuroimaging study of a cohort of 33 cognitively normal patients with amyotrophic lateral sclerosis (ALS) and 44 healthy controls. A voxel-wise generalised linear model was used to investigate the distribution of disease burden within the motor cortex in relation to clinical disability.

RESULTS

Patients with bulbar onset have bilateral focal atrophy in the bulbar segment of the motor homunculus compared with patients with limb onset who have focal cortical changes in the limb segment of their motor strip. Furthermore, the extent to which different body regions are affected in ALS corresponds to the extent of focal grey matter loss in the primary motor cortex. Cortical ALS pathology also extends beyond the motor cortex affecting frontal, occipital and temporal regions.

CONCLUSIONS

Focal grey matter atrophy within the motor homunculus corresponds with functional disability in ALS. The findings support the existing concepts of cortical focality and motor phenotype heterogeneity in ALS.

Multiparametric MRI study of ALS stratified for the C9orf72 genotype

OBJECTIVE

To describe the patterns of cortical and subcortical changes in amyotrophic lateral sclerosis (ALS) stratified for the C9orf72 genotype.

METHODS

A prospective, single-center, single-protocol, gray and white matter magnetic resonance case-control imaging study was undertaken with 30 C9orf72-negative patients with ALS, 9 patients with ALS carrying the C9orf72 hexanucleotide repeat expansion, and 44 healthy controls. Tract-based spatial statistics of multiple white matter diffusion parameters, cortical thickness measurements, and voxel-based morphometry analyses were carried out. All patients underwent comprehensive genetic and neuropsychological profiling.

RESULTS

A congruent pattern of cortical and subcortical involvement was identified in those with the C9orf72 genotype, affecting fusiform, thalamic, supramarginal, and orbitofrontal regions and the Broca area. White matter abnormalities in the C9orf72-negative group were relatively confined to corticospinal and cerebellar pathways with limited extramotor expansion. The body of the corpus callosum and superior motor tracts were affected in both ALS genotypes.

CONCLUSIONS

Extensive cortical and subcortical frontotemporal involvement was identified in association with the C9orf72 genotype, compared to the relatively limited extramotor pathology in patients with C9orf72-negative ALS. The distinctive, genotype-specific pathoanatomical patterns are consistent with the neuropsychological profile of the 2 ALS cohorts. Our findings suggest that previously described extramotor changes in ALS could be largely driven by those with the C9orf72 genotype.

Social cognition in neurodegenerative disorders: a systematic review

Social cognitive neuroscience is the study of the neurobiological systems underlying effective social behaviour. The neural processes supporting effective social interactions in everyday life and the consequences of dysfunction in these processes have been the focus of intense research over the last two decades. It is becoming increasingly apparent that the identification of social cognitive deficits in neurodegenerative conditions and their neural basis may provide a better understanding of the behavioural changes observed in these disorders. In addition, accumulating data suggest that detection of early impairment in social cognitive skills may aid in the early diagnosis of cognitive or behavioural impairment in some of these disorders, and may even play a role in the investigation of new therapeutic options. In this review, we outline the basic components of social cognitive processing, provide a systematic review of the literature pertaining to common neurodegenerative conditions, discuss current controversies and make recommendations for future research.

The syndrome of cognitive impairment in amyotrophic lateral sclerosis: a population-based study

BACKGROUND

Despite considerable interest, the population-based frequency, clinical characteristics and natural history of cognitive impairment in amyotrophic lateral sclerosis (ALS) are not known.

METHODOLOGY

The authors undertook a prospective population-based study of cognitive function in 160 incident Irish ALS patients and 110 matched controls. Home-based visits were conducted to collect demographic and neuropsychological data. Patients were classified using the recently published consensus criteria and by a domain-based classification of both executive and non-executive cognitive processes.

RESULTS

13.8% of patients fulfilled the Neary criteria for frontotemporal dementia. In addition, 34.1% of ALS patients without evidence of dementia fulfilled the recently published consensus criteria for cognitive impairment. Non-demented ALS patients had a significantly higher frequency of impairment in language and memory domains compared to healthy controls. These deficits occurred primarily in patients with executive dysfunction. 14% of ALS patients had evidence of cognitive impairment without executive dysfunction, and no cognitive abnormality was detected in almost half the cohort (46.9%).

CONCLUSION

Co-morbid dementia occurs in approximately 14% of patients with a new diagnosis of ALS. Cognitive impairment, predominantly but not exclusively in the form executive dysfunction, is present in more than 40% of ALS patients who have no evidence of dementia. Cognitive impairment in ALS is not a universal feature, and its manifestations may be more heterogeneous than previously recognised.