Joost Raaphorst

The clinical and pathological phenotype of C9ORF72 hexanucleotide repeat expansions.

There is increasing evidence that frontotemporal dementia and amyotrophic lateral sclerosis are part of a disease continuum. Recently, a hexanucleotide repeat expansion in C9orf72 was identified as a major cause of both sporadic and familial frontotemporal dementia and amyotrophic lateral sclerosis. The aim of this study was to investigate clinical and neuropathological characteristics of hexanucleotide repeat expansions in C9orf72 in a large cohort of Dutch patients with frontotemporal dementia. Repeat expansions were successfully determined in a cohort of 353 patients with sporadic or familial frontotemporal dementia with or without amyotrophic lateral sclerosis, and 522 neurologically normal controls. Immunohistochemistry was performed in a series of 10 brains from patients carrying expanded repeats using a panel of antibodies. In addition, the presence of RNA containing GGGGCC repeats in paraffin-embedded sections of post-mortem brain tissue was investigated using fluorescence in situ hybridization with a locked nucleic acid probe targeting the GGGGCC repeat. Hexanucleotide repeat expansions in C9orf72 were found in 37 patients with familial (28.7%) and five with sporadic frontotemporal dementia (2.2%). The mean age at onset was 56.9 ± 8.3 years (range 39-76), and disease duration 7.6 ± 4.6 years (range 1-22). The clinical phenotype of these patients varied between the behavioural variant of frontotemporal dementia (n = 34) and primary progressive aphasia (n = 8), with concomitant amyotrophic lateral sclerosis in seven patients. Predominant temporal atrophy on neuroimaging was present in 13 of 32 patients. Pathological examination of the 10 brains from patients carrying expanded repeats revealed frontotemporal lobar degeneration with neuronal transactive response DNA binding protein-positive inclusions of variable type, size and morphology in all brains. Fluorescence in situ hybridization analysis of brain material from patients with the repeat expansion, a microtubule-associated protein tau or a progranulin mutation, and controls did not show RNA-positive inclusions specific for brains with the GGGGCC repeat expansion. The hexanucleotide repeat expansion in C9orf72 is an important cause of frontotemporal dementia with and without amyotrophic lateral sclerosis, and is sometimes associated with primary progressive aphasia. Neuropathological hallmarks include neuronal and glial inclusions, and dystrophic neurites containing transactive response DNA binding protein. Future studies are needed to explain the wide variation in clinical presentation.

The cognitive profile of amyotrophic lateral sclerosis: A meta-analysis

We aimed to clarify the profile of cognitive impairment in ALS, by meta-analysis of published studies. Criteria for inclusion were: ALS diagnosed according to El Escorial criteria; control group matched for age and education; correction for bias due to motor impairment or dysarthria; no dementia in patients and controls. Effect sizes reflecting a difference in neuropsychological performance between ALS patients and controls were calculated for 12 cognitive domains. The effect of demographic and clinical variables (age, disease duration, site of onset) on cognition was assessed in a moderator analysis. Of 48 eligible articles, 16 studies encompassing 554 ALS patients were included. Significant effect sizes were found for the Mini Mental State Examination (d=0.8), immediate verbal memory (d=0.5), visual memory (d=0.4), fluency (d=0.5), psychomotor speed (d=0.7), language (d=0.5) and executive functioning (d=0.3). The results of the latter three domains are less reliable due to the possibility of publication bias. Psychomotor speed, and to a lesser extent fluency, may have been influenced by motor impairment, despite attempts to correct for motor slowness. In conclusion, the diversity of cognitive problems in ALS seems greater than was previously thought. ALS patients may suffer from cognitive impairment in multiple domains, including memory dysfunction.

The cognitive profile of ALS: a systematic review and meta-analysis update

Cognitive impairment is present in approximately 30% of patients with amyotrophic lateral sclerosis (ALS) and, especially when severe, has a negative impact on survival and caregiver burden. Our 2010 meta-analysis of the cognitive profile of ALS showed impairment of fluency, executive function, language and memory. However, the limited number of studies resulted in large confidence intervals. To obtain a more valid assessment, we updated the meta-analysis and included methodological improvements (controlled data extraction, risk of bias analysis and effect size calculation of individual neuropsychological tests). Embase, Medline and PsycInfo were searched for neuropsychological studies of non-demented patients with ALS and age-matched and education-matched healthy controls. Neuropsychological tests were categorised in 13 cognitive domains and effect sizes (Hedges’ g) were calculated for each domain and for individual tests administered in ≥5 studies. Subgroup analyses were performed to assess the influence of clinical and demographic variables. Forty-four studies were included comprising 1287 patients and 1130 healthy controls. All cognitive domains, except visuoperceptive functions, showed significant effect sizes compared to controls. Cognitive domains without bias due to motor impairment showed medium effect sizes (95% CI): fluency (0.56 (0.43 to 0.70)), language (0.56 (0.40 to 0.72)), social cognition (0.55 (0.34 to 0.76)), or small effect sizes: delayed verbal memory 0.47 (0.27 to 0.68)) and executive functions (0.41 (0.27 to 0.55)). Individual neuropsychological tests showed diverging effect sizes, which could be explained by bias due to motor impairment. Subgroup analyses showed no influence of bulbar disease onset and depression and anxiety on the cognitive outcomes. The cognitive profile of ALS consists of deficits in fluency, language, social cognition, executive functions and verbal memory. Social cognition is a new cognitive domain with a relatively large effect size, highlighting the overlap between ALS and frontotemporal dementia. The diverging effect sizes for individual neuropsychological tests show the importance of correction for motor impairment in patients with ALS. These findings have implications for bedside testing, the design of cognitive screening measures and full neuropsychological examinations.

Hexanucleotide repeat expansions in C9ORF72 in the spectrum of motor neuron diseases

Objective: To assess the frequency and phenotype of hexanucleotide repeat expansions in C9ORF72 in a large cohort of patients of Dutch descent with familial (fALS) and sporadic (sALS) amyotrophic lateral sclerosis (ALS), progressive muscular atrophy (PMA), and primary lateral sclerosis (PLS). Methods: Included were 78 patients with fALS, 1,422 with sALS, 246 with PMA, and 110 with PLS, and 768 control subjects. Repeat expansions were determined by a repeat primed PCR. Familial aggregation of dementia and Parkinson disease (PD) was examined among patients with ALS who carried the repeat expansion. Results: The expanded repeat was found in 33 (37%) of all patients with fALS, in 87 (6.1%) patients with sALS, in 4 (1.6%) patients with PMA, and in 1 (0.9%) patient with PLS. None of the controls carried the mutation. Patients with ALS with the repeat expansion had an earlier age at onset (median 59.3 vs 61.9 years, hazard ratio 1.55, p = 5 × 10−5) and shorter survival (median 2.5 vs 2.7 years, hazard ratio 1.46, p = 8 × 10−4). Dementia, but not PD, occurred nearly twice as often in relatives of patients with the expansion compared to all patients with ALS or controls (p = 9 × 10−4). Conclusions: The hexanucleotide repeat expansion in C9ORF72 is a major cause of fALS and apparently sporadic ALS in the Netherlands. Patients who carry the repeat expansion have an earlier onset, shorter survival, and familial aggregation of dementia. These results challenge the classic definition of fALS and may justify genetic testing in patients with sALS.

Cognitive dysfunction in lower motor neuron disease: executive and memory deficits in progressive muscular atrophy

Aim In contrast with findings in amyotrophic lateral sclerosis (ALS), cognitive impairments have as yet not been shown in the lower motor neuron variant of motor neuron disease, progressive spinal muscular atrophy (PMA). The objective of this study was to investigate cognitive function in PMA and to compare the cognitive profile with that of ALS. In addition, visuospatial functions were assessed comprehensively; these tests are underrepresented in earlier neuropsychological investigations in ALS. Methods 23 PMA and 30 ALS patients (vital capacity >70% of predicted value) underwent a neuropsychological assessment adapted to motor impairments: global cognitive and executive functioning, psychomotor speed, memory, language, attention and visuospatial skills. The results were compared with age, education and sex matched controls and with normative data. Results Compared with controls, PMA patients performed worse on attention/working memory (digit span backward), category fluency and the Mini-Mental State Examination. Compared with normative data, PMA patients most frequently showed impairment on three measures: letter–number sequencing, and immediate and delayed story recall. 17% of PMA patients showed cognitive impairment, defined as performance below 2 SDs from the mean of normative data on at least three neuropsychological tests. In ALS, similar but more extensive cognitive deficits were found. Visuospatial dysfunction was not found in PMA and ALS. Conclusions 17% of PMA patients have executive and memory impairments. PMA with cognitive impairment adds a formerly unknown phenotype to the existing classification of motor neuron diseases.

A systematic review of behavioural changes in motor neuron disease

Motor neuron disease (MND) and the behavioural variant of frontotemporal dementia (bvFTD) are thought to be part of a disease spectrum. There is uncertainty about the frequency and characteristics of behavioural changes in MND, and similarly, about a relation between bvFTD and the site of onset of MND. Our aim was to perform a systematic review of the publications on behavioural changes in MND. An extensive search for articles on behavioural changes in MND patients was performed. First, cohort studies of MND patients were reviewed to summarize the prevalence of bvFTD and mild behavioural changes. Secondly, data on bvFTD symptoms (mostly from case reports) of individual MND-bvFTD patients were used to analyse characteristics and pooled prevalences of bvFTD symptoms. In addition, site of onset, survival and demographic variables of MND-bvFTD patients were analysed. Results showed that in cohorts, 8.1% (95% CI 5.6 − 11.5%) of MND patients had bvFTD. In 170 individual patients with MND-bvFTD, perseveration (40%), apathy (29%) and disinhibition (26%) were the most frequently reported behavioural changes; 43% had memory disturbances and bulbar onset was found in 48%. In conclusion, 8% of MND patients have bvFTD, with perseveration being reported most frequently. MND-bvFTD is often accompanied by memory disturbances and is related to bulbar onset.

Prose memory impairment in amyotrophic lateral sclerosis patients is related to hippocampus volume.

Thirty per cent of amyotrophic lateral sclerosis (ALS) patients have non‐motor symptoms, including executive and memory deficits. The in vivo anatomical basis of memory deficits in ALS has not been elucidated. In this observational study, brain atrophy in relation to memory function was investigated in ALS patients and controls.

Multicenter evaluation of neurofilaments in early symptom onset amyotrophic lateral sclerosis

Objective To examine neurofilament (Nf) concentrations according to symptom onset and clinical diagnostic certainty categories of amyotrophic lateral sclerosis (ALS). Methods We measured Nf light chain (NfL) and phosphorylated Nf heavy chain (pNfH) CSF and NfL serum levels in patients with ALS with first symptom onset ≤6 months (n = 54) or >6 months (n = 135) from sampling, and patients with other neurologic diseases, differential diagnoses of a motor neuron disease (MND mimics), and other MND variants to determine the diagnostic accuracy in patients with ALS with early symptom onset. Samples were received multicentric and analyzed by ELISA and Simoa platform and related to other clinical measures. Results NfL and pNfH in CSF and NfL in serum were increased in early and later symptomatic phase ALS (p < 0.0001). CSF and serum NfL and CSF pNfH discriminated patients with ALS with early symptom onset from those with other neurologic diseases and MND mimics with high sensitivity (94%, 88%, 98%, and 89%, 100%, 78%) and specificity (86%, 92%, 91%, and 94%, 90%, 98%) and did not vary between clinical diagnostic categories of ALS in the early symptomatic phase group. Baseline NfL and pNfH levels were not significantly different in patients with ALS with clinical progression to definite or probable ALS at follow-up. Conclusion The measurement of Nf has potential to enhance diagnostic accuracy of ALS in those presenting soon after symptom onset, and is measurable across multiple centers. Classification of evidence This study provides Class II evidence that CSF and serum Nf concentrations discriminate ALS with early symptom onset from other neurologic diseases.

Prevalence of brain and spinal cord inclusions, including dipeptide repeat proteins, in patients with the C9ORF72 hexanucleotide repeat expansion: A systematic neuropathological review.

The current literature shows no consensus on the localization and number of characteristic neuronal inclusions [p62 and dipeptide repeat proteins (DRPs) positive, TDP‐43‐negative and TDP‐43 positive] in the brain and spinal cord of patients with the hexanucleotide repeat expansion on chromosome 9 (C9ORF72‐positive patients). This may be due to small sample sizes. A valid brain map of the inclusions in C9ORF72‐positive patients may improve clinicopathological correlations and may serve as a reference for neuropathologists.

Prefrontal involvement related to cognitive impairment in progressive muscular atrophy

Objective: To examine brain activation patterns during verbal fluency performance in patients with progressive muscular atrophy (PMA) and amyotrophic lateral sclerosis (ALS). Methods: fMRI was used to examine the blood oxygen level–dependent response during letter and category fluency performance in 18 patients with PMA, 21 patients with ALS, and 17 healthy control subjects, matched for age and education. fMRI results are reported at p < 0.05, family-wise error (FWE)-corrected for multiple comparisons. We analyzed effects of performance, age-related white matter changes (ARWMC), and regional brain volumes; all participants underwent neuropsychological investigation. Results: Disease duration of patients with PMA (mean 26.0 months, SD 13.6) and ALS (22.2 months, SD 11.4) was comparable. Patients with PMA and ALS had mild to moderate disease severity and showed impaired letter fluency compared with controls. Between-group analysis showed a main effect of group in the left inferior frontal gyrus (IFG, Brodmann area 45) during letter fluency, which was unaffected by performance, ARWMC, and IFG volume: patients with PMA showed lower activation than controls but higher than that of patients with ALS (ALS < PMA < healthy controls; pFWE = 0.035; z score 4.11; cluster size = 11). A more caudal region in the IFG showed lower activation in patients with PMA than controls during letter fluency performance (post hoc test; pFWE = 0.026). No activation differences were observed during the category fluency task. Conclusion: Prefrontal activation abnormalities are related to an important clinical measure of executive dysfunction in patients with motor neuron disease with and without upper motor neuron signs.