Aim: We conducted a study to investigate whether patients with somatization disorders (ICD-10, F45.0) show abnormal values in autonomic testing.
Method: 35 patients with a diagnosis of somatization disorder (SP) were matched to 35 healthy volunteers (HV). International standardized autonomic testing based on heart rate variation and continuously measured blood pressure signals was used to assess autonomic activity and establish baroreceptor sensitivity (BRS). Three different statistical procedures were used to confirm the reliability of the findings.
Results: There were no statistical differences between the 2 groups in age, BMI, systolic and diastolic blood pressures, and spectral values (total power, low, and high frequency power). However, heart rate was higher (p=0.044) and baroreceptor sensitivity was lower (p=0.002) in the patients compared to the healthy volunteers. Median BRS (+/-S.E.M.) of patients was 9.09+/-0.65 compared to 12.04+/-0.94 ms/mmHg in healthy volunteers. Twenty-two of the 35 patients had a BRS of -1.0S.D. below the mean of HV. SP with lower values differed from SP with normal BRS in values of total power, low-, mid-, and high-frequency bands (p<0.01 to <0.0001). No differences in psychometric testing were found between patients with lower or higher BRS. In addition, no correlation whatsoever was found in relation to autonomic variables between HV and SP, except for a higher LF/HF quotient in the latter (p<0.05).
Conclusion: Autonomic regulation was impaired in 62% of patients with a somatization disorder. Severity of clinical symptoms measured by psychometric instruments did not preclude autonomic function impairment. Accordingly, autonomic dysfunction may constitute an independent somatic factor in this patient group.