## 2 Dataset
### Sample Characterisation  
The database contained data from 48 adults with TD (24 women, 50%) and 11 adults with ASD (2 women, 18.18%), aged between 19 and 59 years. Sociodemographic characterisation is presented in Table 1. Only participants meeting the inclusion/exclusion criteria were included in the database: being aged between 18 and 59 years; being Caucasian; speaking fluent German; being capable of understanding and following instructions; having no illnesses problems (e.g., common flue), or regular medication intake affecting the sense of smell; not being pregnant or lactating at the time of assessment, and not having participated in the BO collection. Handedness was assessed with the Edinburgh Handedness Inventory (EHI) [36], with all but one participant being considered right-handed.  
The ASD diagnosis was based on the DSM criteria (mostly 5 th edition) by independent clinicians and ASD symptoms were evaluated with the German version of the Autism Diagnostic Observation Schedule (ADOS) [37]. Lastly, adults with TD had no mental illness, as confirmed with the German version of the Structured Clinical Interview (SCID-I) [38], and no first-degree relative diagnosed with psychotic disorder or ASD, as self-stated.  
Alongside the ADOS (for the ASD group) and the SCID-I (for the TD group), all participants completed a sociodemographic questionnaire and the Sniffin' Sticks Test (Burghart Medizintechnik, Germany). The Sniffin' Sticks Test is a widely used instrument to measure olfactory abilities (see [39]). The test comprises three subtests (odour threshold, identification, and discrimination) and uses odour-dispensing pens with 4 mL of odourant fluid or odourant substance dissolved in propylene glycol. In addition to scores for each subset (maximum of 16), the Sniffin' Sticks Test contains a final score, ranging from 1 to 48. Hyposmia and functional anosmia are established, on the reference group of 21 to 30 years,  
\begin{table}
\begin{tabular}{l l c c c} \hline \hline  & & **ASD** & **TD** & **\(p\)-Value 1** \\  & & **_n_ = 11** & **_n_ = 48** & \\ \hline Age, _Mdn (IQR)_ & & 36.0 (17.5) & 24.50 (9.5) & 0.002 ** \\ Sex, \(n\) (\%) & Women & 2 (18.2) & 24 (50.0) & 0.091 \\  & Men & 9 (81.8) & 24 (50.0) & \\ Nationality, \(n\) (\%) & German & 10 (90.9) & 45 (93.8) & 0.168 \\  & Swiss & 0 (0.0) & 2 (4.2) & \\  & Hungarian & 1 (9.1) & 0 (0.0) & \\  & Bulgarian & 0 (0.0) & 1 (2.1) & \\ Working status, \(n\) (\%) & Full-time worker & 5 (45.4) & 6 (12.5) & 0.001 *** \\  & Part-time worker & 2 (18.2) & 3 (6.3) & \\  & Pensioner & 2 (18.2) & 0 (0.0) & \\  & Stick leave & 1 (9.1) & 0 (0.0) & \\  & Student & 1 (9.1) & 37 (77.1) & \\  & Working student & 0 (0.0) & 1 (2.1) & \\  & Unemployed & 0 (0.0) & 1 (2.1) & \\ Smoking habits, \(n\) (\%) & Non-smoker & 8 (72.7) & 36 (75.0) & 0.114 \\  & 1-5 cigarettes/week & 0 (0.0) & 8 (16.7) & \\  & 5–10 cigarettes/week & 0 (0.0) & 0 (0.0) & \\  & 10–15 & 0 (0.0) & 1 (2.1) & \\  & cigarettes/week & Daily & 3 (27.3) & 3 (6.3) & \\ Hormonal contraceptive, \(n\) (\%) & Yes & 0 (0.0) & 10 (41.7) & 0.395 \\  & No & 2 (100.0) & 12 (50.0) & \\  & Menopause & 0 (0.0) & 2 (8.3) & \\ EHI, _Mdn (IQR)_ & & 100 (0) & 100 (0) & 0.894 \\ Sniffin’ Sticks, _Mdn (IQR)_ & Threshold & 5.2 (2.4) & 7.6 (2.2) & 0.008 ** \\  & Discrimination & 11.0 (1.5) & 13.0 (2.0) & 0.040 * \\  & Identification & 13.0 (1.0) & 14.0 (2.0) & 0.176 \\  & Total & 27.7 (2.7) & 33.2 (3.6) & 0.002 ** \\ \hline \hline \end{tabular}
\end{table}
Table 1: Characterisation of the sample. Notes. EHI, Edinburgh Handedness Inventory. 1 Comparisons between groups were performed with Mann–Whitney Test (for continuous variables) and Fisher’s Exact Test or Chi-Squared Test (for categorical variables). * \(p\) \(<\) 0.050; ** \(p\) \(<\) 0.010; *** \(p\) \(<\) 0.001.  
at a final score of less than 30.75 and 16 points, respectively (see [40]). Data concerning the Sniffin' Sticks Test are described in Table 1.