Neurological Soft Signs in Type I Bipolar Disorder and Bipolar Spectrum Patients and Their Unaffected First-Degree Relatives: A Cross-Sectional Study.

Background and aims: This study aimed to compare neurological soft signs (NSSs) in type 1 bipolar disorder (BD), bipolar spectrum (BS) patients, and their unaffected first-degree relatives.

Methods: This descriptive cross-sectional study involved participants referred to the Psychiatric Department of Imam Hossein Hospital. Five groups (n = 25): patients with type 1 BD, patients with BS, unaffected first-degree relatives of the two groups, and a control group were evaluated using the Neurological Evaluation Scale (NES).

Results: The analysis revealed that patients with bipolar I disorder had the highest NES scores, with significant group differences (F(4.120) = 10.36, p < 0.001). The Bonferroni correction identified bipolar I patients as the primary source of this difference, while other groups did not significantly differ. ANCOVA showed that age (F(1.123) = 3.92, p = 0.052) and gender (F(1.123) = 0.1, p = 0.75) had no significant influence on NES scores. However, all four NES subsets significantly contributed to the overall score, except for the sensory subset. Differences were significant between bipolar I patients and most other groups, except the BS group, which showed no significant differences from the rest. No correlation was found with age, gender, or age of disease onset.

Conclusion: The higher NSS severity in type I BD compared to BS and control groups highlights its potential link to the genetic and neurodevelopmental differences in BD type I. Further research is recommended.