Clinicoradiological and neuropathological evaluation of primary progressive aphasia

BACKGROUND

Primary progressive aphasia (PPA) defines a group of neurodegenerative disorders characterised by language decline. Three PPA variants correlate with distinct underlying pathologies: semantic variant PPA (svPPA) with transactive response DNA-binding protein of 43 kD (TDP-43) proteinopathy, agrammatic variant PPA (agPPA) with tau deposition and logopenic variant PPA (lvPPA) with Alzheimer's disease (AD). Our objectives were to differentiate PPA variants using clinical and neuroimaging features, assess progression and evaluate structural MRI and a novel 18-F fluorodeoxyglucose positron emission tomography (FDG-PET) image decomposition machine learning algorithm for neuropathology prediction.

METHODS

We analysed 82 autopsied patients diagnosed with PPA from 1998 to 2022. Clinical histories, language characteristics, neuropsychological results and brain imaging were reviewed. A machine learning framework using a k-nearest neighbours classifier assessed FDG-PET scans from 45 patients compared with a large reference database.

RESULTS

PPA variant distribution: 35 lvPPA (80% AD), 28 agPPA (89% tauopathy) and 18 svPPA (72% frontotemporal lobar degeneration-TAR DNA-binding protein (FTLD-TDP)). Apraxia of speech was associated with 4R-tauopathy in agPPA, while pure agrammatic PPA without apraxia was linked to 3R-tauopathy. Longitudinal data revealed language dysfunction remained the predominant deficit for patients with lvPPA, agPPA evolved to corticobasal or progressive supranuclear palsy syndrome (64%) and svPPA progressed to behavioural variant frontotemporal dementia (44%). agPPA-4R-tauopathy exhibited limited pre-supplementary motor area atrophy, lvPPA-AD displayed temporal atrophy extending to the superior temporal sulcus and svPPA-FTLD-TDP had severe temporal pole atrophy. The FDG-PET-based machine learning algorithm accurately predicted clinical diagnoses and underlying pathologies.

CONCLUSIONS

Distinguishing 3R-taupathy and 4R-tauopathy in agPPA may rely on apraxia of speech presence. Additional linguistic and clinical features can aid neuropathology prediction. Our data-driven brain metabolism decomposition approach effectively predicts underlying neuropathology.

Improved naming in patients with Broca's aphasia with tDCS

BACKGROUND

Language impairment (aphasia) is a common neurological deficit after strokes. For individuals with chronic aphasia (beyond 6 months after the stroke), language improvements with speech therapy (ST) are often limited. Transcranial direct current stimulation (tDCS) is a promising approach to complement language recovery but interindividual variability in treatment response is common after tDCS, suggesting a possible relationship between tDCS and type of linguistic impairment (aphasia type).

METHODS

This current study is a subgroup analysis of a randomised controlled phase II futility design clinical trial on tDCS in chronic post-stroke aphasia. All participants received ST coupled with tDCS (n=31) vs sham tDCS (n=39). Confrontation naming was tested at baseline, and 1, 4, and 24 weeks post-treatment.

RESULTS

Broca's aphasia was associated with maximal adjunctive benefit of tDCS, with an average improvement of 10 additional named items with tDCS+ST compared with ST alone at 4 weeks post-treatment. In comparison, tDCS was not associated with significant benefits for other aphasia types F(1)=4.23, p=0.04. Among participants with Broca's aphasia, preservation of the perilesional posterior inferior temporal cortex was associated with higher treatment benefit (R=0.35, p=0.03).

CONCLUSIONS

These results indicate that adjuvant tDCS can enhance ST to treat naming in Broca's aphasia, and this may guide intervention approaches in future studies.

Primary progressive aphasia: ReADing the clinical GRANularity

Primary progressive aphasia remains a diagnostic challenge despite (or even because of) the increasing availability of ancillary tests and biomarkers. We present a 67-year-old man with apparently sporadic logopenic aphasia and positive Alzheimer biomarkers who was subsequently found also to have a pathogenic mutation in the progranulin gene. This was signalled by early atypical features (mild expressive agrammatism and behavioural change, rapid clinical deterioration) around the core logopenic aphasia syndrome. Each of the canonical progressive aphasia syndromes has a 'halo' of less typical variants that may herald alternative or additional pathologies. The accurate diagnosis of primary progressive aphasia depends on careful clinical analysis to direct investigations appropriately.

Computerised speech and language therapy or attention control added to usual care for people with long-term post-stroke aphasia: the Big CACTUS three-arm RCT

BACKGROUND

People with aphasia may improve their communication with speech and language therapy many months/years after stroke. However, NHS speech and language therapy reduces in availability over time post stroke.

OBJECTIVE

This trial evaluated the clinical effectiveness and cost-effectiveness of self-managed computerised speech and language therapy to provide additional therapy.

DESIGN

A pragmatic, superiority, single-blind, parallel-group, individually randomised (stratified block randomisation, stratified by word-finding severity and site) adjunct trial.

SETTING

Twenty-one UK NHS speech and language therapy departments.

PARTICIPANTS

People with post-stroke aphasia (diagnosed by a speech and language therapist) with long-standing (> 4 months) word-finding difficulties.

INTERVENTIONS

The groups were (1) usual care; (2) daily self-managed computerised word-finding therapy tailored by speech and language therapists and supported by volunteers/speech and language therapy assistants for 6 months plus usual care (computerised speech and language therapy); and (3) activity/attention control (completion of puzzles and receipt of telephone calls from a researcher for 6 months) plus usual care.

MAIN OUTCOME MEASURES

Co-primary outcomes - change in ability to find treated words of personal relevance in a bespoke naming test (impairment) and change in functional communication in conversation rated on the activity scale of the Therapy Outcome Measures (activity) 6 months after randomisation. A key secondary outcome was participant-rated perception of communication and quality of life using the Communication Outcomes After Stroke questionnaire at 6 months. Outcomes were assessed by speech and language therapists using standardised procedures. Cost-effectiveness was estimated using treatment costs and an accessible EuroQol-5 Dimensions, five-level version, measuring quality-adjusted life-years.

RESULTS

A total of 818 patients were assessed for eligibility and 278 participants were randomised between October 2014 and August 2016. A total of 240 participants (86 usual care, 83 computerised speech and language therapy, 71 attention control) contributed to modified intention-to-treat analysis at 6 months. The mean improvements in word-finding were 1.1% (standard deviation 11.2%) for usual care, 16.4% (standard deviation 15.3%) for computerised speech and language therapy and 2.4% (standard deviation 8.8%) for attention control. Computerised speech and language therapy improved word-finding 16.2% more than usual care did (95% confidence interval 12.7% to 19.6%; p < 0.0001) and 14.4% more than attention control did (95% confidence interval 10.8% to 18.1%). Most of this effect was maintained at 12 months (n = 219); the mean differences in change in word-finding score were 12.7% (95% confidence interval 8.7% to 16.7%) higher in the computerised speech and language therapy group (n = 74) than in the usual-care group (n = 84) and 9.3% (95% confidence interval 4.8% to 13.7%) higher in the computerised speech and language therapy group than in the attention control group (n = 61). Computerised speech and language therapy did not show significant improvements on the Therapy Outcome Measures or Communication Outcomes After Stroke scale compared with usual care or attention control. Primary cost-effectiveness analysis estimated an incremental cost per participant of £732.73 (95% credible interval £674.23 to £798.05). The incremental quality-adjusted life-year gain was 0.017 for computerised speech and language therapy compared with usual care, but its direction was uncertain (95% credible interval -0.05 to 0.10), resulting in an incremental cost-effectiveness ratio of £42,686 per quality-adjusted life-year gained. For mild and moderate word-finding difficulty subgroups, incremental cost-effectiveness ratios were £22,371 and £28,898 per quality-adjusted life-year gained, respectively, for computerised speech and language therapy compared with usual care.

LIMITATIONS

This trial excluded non-English-language speakers, the accessible EuroQol-5 Dimensions, five-level version, was not validated and the measurement of attention control fidelity was limited.

CONCLUSIONS

Computerised speech and language therapy enabled additional self-managed speech and language therapy, contributing to significant improvement in finding personally relevant words (as specifically targeted by computerised speech and language therapy) long term post stroke. Gains did not lead to improvements in conversation or quality of life. Cost-effectiveness is uncertain owing to uncertainty around the quality-adjusted life-year gain, but computerised speech and language therapy may be more cost-effective for participants with mild and moderate word-finding difficulties. Exploring ways of helping people with aphasia to use new words in functional communication contexts is a priority.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN68798818.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 19. See the NIHR Journals Library website for further project information. The Tavistock Trust for Aphasia provided additional support to enable people in the control groups to experience the intervention after the trial had ended.

EFFECT OF WORD FREQUENCY AND WORD LENGTH ON APHASIC SPELLING ERRORS

The Wide Range Achievement Spelling Test was administered to 64 aphasic subjects. Total errors on each of the 100 test words and errors made by subjects in each quartile were analyzed in relation to the logarithm of word frequency, and word length determined by number of letters. Both word length and word frequency were found to be significant variables in determining the spelling performance of aphasic subjects. Word frequency and word length were negatively correlated, and accounted almost completely for the errors on the test words in all segments of the population.