What is Primary Progressive Aphasia?
Primary Progressive Aphasia (or ‘PPA’) is a syndrome, caused by degeneration of brain cells, which begins with selective difficulty producing and/or understanding spoken language. As the degeneration becomes worse, language difficulties become more profound, while other cognitive abilities (such as memory, organisation, problem solving and visual discrimination) remain relatively intact. The syndrome is therefore thought to represent disruption of the extensive, left hemisphere ‘language network’. Depending on which part of this network is most severely damaged, PPA can take a variety of forms, and three distinct patterns are currently recognised. Some patients experience a reduced ability to appreciate the meaning of words or objects (‘semantic dementia’), while in others the problems lie in the production of words and sentences (‘progressive nonfluent aphasia’). A third group displays milder problems, along with a striking inability to repeat spoken sentences (‘logopenic progressive aphasia’).
How does Primary Progressive Aphasia differ from post-stroke aphasia?
Post-stroke aphasia results from stroke or brain injury whereas primary progressive aphasia (PPA) is a neurological disorder in which language capabilities become slowly and progressively impaired due to neurodegeneration within the language network. Neurodegeneration can be caused by processes such as Alzheimer’s disease or frontotemporal lobar degeneration. Both PPA and post stroke aphasia result from disruption of brain tissue within the language network. A large scale systematic comparison of the features of aphasia seen in the two conditions would be highly informative to our understanding of the biological basis of language. The comparison is technically difficult, but development of an MLSE will undoubtedly facilitate it.
Is the MLSE free to use?
When fully validated, the MLSE will be free to use for clinical and academic purposes for which it is licensed under Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0). A licence agreement will be required for any form of commercial use.
Why is the MLSE only available in English and Italian?
We hope that the MLSE will eventually be widely available across many language communities, but it would be unrealistic to try to develop versions for all major languages at once, so we are starting out concentrating on two European languages – English and Italian – the native languages of around 360 million and 60 million people, respectively. We will ensure that the same classifications emerge from the MLSE as are currently recognised by expert clinicians by validating the test against expert clinical opinion, and against the patterns of aphasia suffered by patients following a stroke.
Can I adapt the MLSE for use in another language?
Once the MLSE has been validated in English and Italian, we will publish a protocol governing its modification and validation in speakers of other languages.
The principles of the protocol will ensure that:
i) Copyright of the MLSE will be under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
ii) In the creation of any new version, individual test stimuli can be replaced by linguistically and culturally appropriate items, with the proviso that the modified subtest is associated with a similar level of difficulty (as measured by the mean percentage accuracy achieved by groups of at least twenty age-matched controls on each item in the subtest) as those in the English and Italian versions. In general, this will equate to a mean of between 95 and 99 percent accuracy.
iii) Each new version will also have a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
iv) The general structure, layout, scoring conventions and format of the test will remain identical to the English and Italian versions, unless there are valid reasons for more fundamental modification.
v) When there is believed to be a need for more fundamental modification, the proposed change will be subject to approval by the MLSE project group investigators.
vi) The psychometric and diagnostic properties of any new version must be shown to be equivalent to the English and Italian versions.
vii) No publication relating to the methods of the MLSE or data acquired using it will be submitted until reports of the initial English and Italian versions (either jointly or separately) have been published.
viii) If the MLSE is used commercially, the IP share belonging to each contributing institution will be negotiated under an inter-institutional agreement.
Cut-off scores
Cut-off scores for the MLSE are currently unavailable but will be published in due course.