Why?

This is of course not very academic, and so far mostly based on absolutely-not-citable personal experience, but I think another reason why neurodiversity and conlanging go well together is simply individuals identifying as neurodivergent (including autistic) are anecdotally over-represented in the conlanging community; to the point that it has been questioned whether a community for neurodivergent conlangers might not be redundant, given that there are hardly any neurotypical conlangers…

It would be possible (and fun!) to speculate about the reasons for this, but to keep things brief here, I’ll just mention that some aspects of conlanging can be argued to be related to previously theorised autistic or neurodivergent ways of experiencing the world, such as firstly a sensory and playful experience of language, and secondly a tendency to interrogate concepts generally held to be ‘common sense’ (Nocon, Roestorf and Gutiérrez Menéndez 2022).

Language is at the heart of autism theories in the two dominant, diametrically opposed, paradigms regarding neurodivergence identified by neurodiversity studies, namely the pathology and the neurodiversity paradigm (cf. Nick Walker’s foundational definitions): the former construes autism as a communication disorder involving autistic language deficits, whereas the latter reframes supposed deficits as language/communication differences.
Reframing cross-neurotype communication (here, communication between autistic and non-autistic individuals) as cross-cultural communication is not a new concept; neurodivergent individuals have long stated some forms of neurodivergence, such as autism, may constitute languages in their own right – though it should always be borne in mind that neurodivergence also always goes deeper than solely language. Early examples of this idea can be seen in the influential 2007 video ‘In My Language’ by non-speaking autistic advocate Mel Baggs (RIP) or Jim Sinclair’s seminal 1993 essay ‘Don’t Mourn For Us’:

‘It takes more work to communicate with someone whose native language isn’t the same as yours. And autism goes deeper than language and culture; autistic people are “foreigners” in any society. You’re going to have to give up your assumptions about shared meanings.’

Autistic researcher Rachel Cullen termed this the ‘Autistic Language Hypothesis’ (click here for an explanation from Ryan Boren’s excellent Stimpunks page), building on Milton’s concept of the ‘Double Empathy Problem’ (DEP). The DEP reframes autism relationally, i.e. as a dispositional mismatch between an autistic and a non-autistic party, where the blame for any miscommunication falls on the autistic party (Milton 2012). As the DEP shows, neurodivergence and especially autism are intimately tied to communication and language. More detailed explainers on the DEP can be found from numerous great online resources such as the ever-reliable Stimpunks or Helen Edgar’s Autistic Realms.

Given the further connection between language/communication and culture, a constructed language (‘conlang’)—a language developed artificially by a creator—is the ideal medium to interrogate neuronormative communication because it sidesteps the issue of natural languages’ cultural baggage/history, with many of the dominant world languages carrying a colonialist legacy and many preconceptions invisibly in-built into language.
Based on the above considerations, the proposed thesis employs the process of developing a ‘naturalistic’ conlang—a conlang that could plausibly have developed naturally through historical processes as per the current state of linguistics—incorporating characteristics of autistic communication and language to critique the pathologisation of autistic and (neuro)divergent language/communication.

The methodology also constitutes an arguably neurodivergent form of practice, given the multiple intersections of neurodivergence and conlanging. Chief among those is that anecdotal experience shows that neurodivergent individuals are disproportionately over-represented in the conlanging community (see above).