## 3 Results  
Sociodemographic Characteristics of the Whole Sample and Correlation between EEG Frequency Bands and Duration of Symptoms  
Participants had a mean duration of symptoms of 20.69 (13.60) years and presented a FIQ score of 48.45 (15.21). Most of the participants had primary education (48.30%) or secondary education (41.40%) levels. Eleven participants (37.95%) were taking antidepressant medication and 10 (34.5%) were taking analgesic/relaxants medication. The complementary therapies that participants reported include massages (17.25%), or physiotherapy (27.6%) (see Table 1). \begin{table}
\begin{tabular}{c c} \hline \hline  & **Participants (N = 29)** \\
**Variable** & **Mean (SD)** \\  & **Frequency (\%)** \\ \hline Age (years) & 55.89 (9.50) \\ \(\leq\)45 (frequency and \(\%\)) & 4 (13.80\%) \\
45-50 (frequency and \(\%\)) & 8 (27.59\%) \\
51–60 (frequency and \(\%\)) & 8 (27.59\%) \\ \(\geq\)61 (frequency and \(\%\)) & 9 (31.02\%) \\ Duration of symptoms & 20.69 (13.60) \\ \(\leq\)10 years & 7 (24.14\%) \\
11–20 years & 9 (31.02\%) \\
21–30 years & 7 (24.14\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Sociodemographic characteristics of the whole sample. [PERSON] and [PERSON]'s Tau-b revealed positive correlations between the years for which participants (N = 29) were suffering from fibromyalgia and the theta power in different scalp locations. These locations comprised the frontal (Fp1 and Fz), central (Cz), and parietal (P3 and Pz) areas (see Table 2). No other significant correlations were found between the duration of fibromyalgia symptoms and the remaining frequency bands (alpha, beta-1, beta-2, or beta-3) (see Table 2). \begin{table}
\begin{tabular}{c c} \hline \hline  & **Participants (N = 29)** \\
**Variable** & **Mean (SD)** \\  & **Frequency (\%)** \\ \hline \(\geq\)31 years & 6 (20.70\%) \\ FIQ-100 & 48.45 (15.21) \\ Stiffness & 5.21 (2.72) \\ Sadness & 3.55 (2.87) \\ Pain & 6.00 (2.28) \\ Anxiety & 5.48 (2.63) \\ Education level (n of patients) \\ \multicolumn{2}{c}{Able to write and read a  } \\ \multicolumn{2}{c}{Primary education} & 14 (48.30\%) \\ Secondary education & 12 (41.40\%) \\ Higher education & 2 (6.90\%) \\ Medication (n of patients) \\ Antidepressants & 11 (37.9\%) \\ Analgesics/relaxants & 10 (34.5\%) \\ Complementary therapies \\ Massages & 5 (17.2\%) \\ Physiotherapy & 8 (27.6\%) \\ Comorbidities \\ Type 2 diabetes & 2 (6.9\%) \\ Hyperlipidemia & 7 (24.1\%) \\ Hypertension & 7 (24.1\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{4}{c}{**Years Suffering from Fibromyalgiaia Symptoms**} & \multicolumn{4}{c}{**Age of the Participants**} \\ \hline
**EEG Scalg** & **Spearman Rho** & **Kendall’s** & **\
\begin{tabular}{c} **Kendall’s** & **
\begin{tabular}{c} **Spearman Rho** \\ **-Value** \\ **-BValue** \\ **Correlation** \\ \hline Fp1 & 0.264 & 0.046 1  & 0.401 & 0.031  & 0.070 & 0.598 & 0.115 & 0.552 \\ Fp2 & 0.179 & 0.176 & 0.238 & 0.213 & \(-\)0.101 & 0.452 & \(-\)0.155 & 0.421 \\ Fz & 0.276 & 0.037 1  & 0.408 & 0.028  & 0.013 & 0.925 & 0.068 & 0.725 \\ F3 & 0.154 & 0.244 & 0.249 & 0.192 & \(-\)0.085 & 0.522 & \(-\)0.049 & 0.802 \\ F4 & 0.247 & 0.063 & 0.348 & 0.065 & 0.013 & 0.925 & 0.022 & 0.908 \\ F7 & 0.177 & 0.182 & 0.341 & 0.071 & 0.1 In addition, Spearman Rho and Kendall's Tau-b did not report any significant correlation between EEG frequency bands and the age of the participants. Between-Group Differences in Sociodemographic Characteristics, Age, Impact of Fibromyalgia, and EEG Power Spectrum  
Participants were divided into two groups (longer and shorter duration of symptoms), taking into account the median duration of symptoms: 17 years. Table 3 summarizes the main sociodemographic characteristics of the two sub-groups.