Social media research on mental health has focused predominantly on detecting and diagnosing conditions at the individual level. In this work, we shift attention to intergroup behavior, examining how two prominent neurodivergent communities, ADHD and autism, adjust their language when engaging with each other on Reddit. Grounded in Communication Accommodation Theory (CAT), we first establish that each community maintains a distinct linguistic profile as measured by Language Inquiry and Word Count Lexicon (LIWC). We then show that these profiles shift in opposite directions when users cross community boundaries: features that are elevated in one group's home community decrease when its members post in the other group's space, and vice versa, consistent with convergent accommodation. The involvement of topic-independent summary variables (Authentic, Clout) in these shifts provides partial evidence against a purely topical explanation. Finally, in an exploratory longitudinal analysis around the moment of public diagnosis disclosure, we find that its effects on linguistic style are small and, in some cases, directionally opposite to cross-community accommodation, providing initial evidence that situational audience adaptation and longer-term identity processes may involve different mechanisms. Our findings contribute to understanding intergroup communication dynamics among neurodivergent populations online and carry implications for community moderation and clinical perspectives on these conditions.
Figures & tables
Figure 1: Bidirectional linguistic accommodation between neurodivergent Reddit communities. r/ADHD (blue, n=7,758 ) is characterised by higher time , Authentic , achieve , and work ; r/autism (red, n=5,706 ) by higher Social , socrefs , Clout , and they . Each dot is a cross-posting user; colour shifts (blue → purple → red) indicate accommodation toward host norms.
Dataset
Users
Posts
Avg Words
Std
Subreddit
Comments
Submissions
ADHD in ADHD
7,758
199,020
85.94
112.21
r/ADHD
171,028
27,992
ADHD in Autism
788
12,621
70.96
113.82
r/autism
11,245
1,376
Autism in Autism
5,706
276,159
64.93
98.54
r/autism
248,597
27,562
Autism in ADHD
2,305
38,470
84.01
108.22
r/ADHD
31,947
6,523
Table 1: Descriptive statistics for cross-posting datasets. Users are non-overlapping between ADHD and autism diagnostic groups.
Figure 2: Study design. From the Mindset dataset, we extract ADHD- and autism-diagnosed users, partition their posts by subreddit into four cross-community datasets, apply LIWC-22 feature extraction with user-level aggregation, and conduct three experiments testing baseline differences (E1), cross-community accommodation (E2), and exploratory post-diagnosis changes (E3). Green boxes indicate supported hypotheses; yellow indicates partial/exploratory support.
Category
ADHD
Autism
d [95% CI]
time
5.62
3.93
0.76 [.72, .80]
achieve
1.59
0.95
0.60 [.56, .64]
Authentic
78.4
69.4
0.59 [.55, .63]
work
2.09
1.26
0.58 [.54, .62]
socrefs
5.05
6.68
− 0.56 [.52, .60]
substances
0.46
0.05
0.55 [.51, .59]
Table 2: Baseline linguistic differences (E1, top 10).
Category
ADHD → Aut.
Aut. → ADHD
d [95% CI]
d [95% CI]
Authentic
− .61 [.53,.69]
+ .33 [.29,.37]
time
− .70 [.62,.78]
+ .43 [.39,.47]
Social
+ .44 [.36,.52]
− .47 [.43,.51]
Clout
+ .43 [.35,.51]
− .31 [.27,.35]
socrefs
+ .45 [.37,.53]
− .47 [.43,.51]
Table 3: Cross-community accommodation (E2).
Category
Dataset
E2 d
E3 d
Authentic
ADHD → Aut.
−0.61
−0.09
Aut. → ADHD
+0.33
−0.12
Clout
ADHD → Aut.
+0.43
+0.11
Aut. → ADHD
−0.31
+0.11
Social
ADHD → Aut.
+0.44
−0.02
Aut. → ADHD
−0.47
+0.02
Table 4: E2 (accommodation) vs. E3 (post-diagnosis) effect sizes.
Appendix figures & tables5 assets
Supplementary material from the paper’s appendix.
Appendix
Figure 3: (a) Baseline differences (E1). (b) Cross-community accommodation (E2): mirror-imaged shifts across every category. (c) E2 vs. E3: accommodation (solid) is 3–23 × larger than post-diagnosis changes (light).
Category
ADHD
Autism
d
time
5.621
3.929
0.76
achieve
1.585
0.950
0.60
Authentic
78.41
69.37
0.59
work
2.091
1.255
0.58
socrefs
5.047
6.682
− 0.56
substances
0.462
0.050
0.55
Appendix
Table 5: Baseline differences (E1, top 15 by ∣d∣ ).
Category
Higher at E1
ADHD → Aut.
Aut. → ADHD
Authentic
ADHD
↓
↑
time
ADHD
↓
↑
Social
Autism
↑
↓
Clout
Autism
↑
↓
socrefs
Autism
↑
↓
health
ADHD
↓
↑
Appendix
Table 6: E1 baseline direction vs. E2 shift direction.
Dataset
Category
Pre
Post
Shift
d
95% CI
ADHD in Aut.
health
2.45
1.65
−0.80
−0.22
[ −.36 , −.08 ]
prep
11.12
10.25
−0.87
−0.20
[ −.34 , −.06 ]
Aut. in ADHD
Authentic
77.22
74.21
−3.00
−0.12
[ −.20 , −.04 ]
Clout
19.30
22.12
+2.82
+0.11
[ +.03 , +.19 ]
i
8.81
8.30
−0.51
−0.11
[ −.19 , −.03 ]
they
0.59
0.69
+0.11
+0.10
[ +.02 , +.18 ]
Appendix
Table 7: Longitudinal changes after diagnosis disclosure (exploratory E3).
Aug 29, 2026·Renkai Ma, Lingyao Li, Shanting Chen +3Mental Health
College of Information Science University of Arizona Tucson, Arizona, USA · Department of Computer and Information Science and Engineering University of Florida Gainesville, Florida, USA