Neurological soft signs and olfactory dysfunction in patients with borderline personality disorder

Borderline personality disorder (BPD) is a serious disorder with a lifetime prevalence of 2.7-5.9% and is thought to correlate with altered neuroplasticity. The aim of the present study is to investigate possible associations of BPD (-severity) and alterations in neurological soft signs (NSS) and olfactory function.

For the monocentric observational study, 39 female subjects with a BPD diagnosis and 19 female healthy control subjects were recruited. The groups were matched by age. Olfactory functions were examined using Sniffin' Sticks. NSS were assessed by a standardized test with 50 items.

BPD subjects have higher NSS scores in group comparison. By contrast, there are no alterations in the total score of olfactory function, while the BPD subjects scored higher in smell identification. Within the BPD group, the total NSS score was discovered to have a negative correlation with olfactory function. BPD subjects taking antipsychotics show more NSS than those without. We found no significant influence of posttraumatic stress disorder on the NSS or olfactory function. The BPD-severity correlates with NSS.

Due to the cross-sectional design, we did not have a follow up examination. The sample size was small, and all patients had psychiatric comorbidities. Additionally, we did not perform MRI to connect our findings with possible structural abnormalities.

Our study confirmed altered NSS in BPD patients, whereas no impairment in the olfactory function was found. Further research is required to establish NSS and smell tests as clinical screening tools in BPD patients and to uncover the disorder's impact on neuroplasticity.