Phd in CLINICAL EXPERIMENTAL NEUROSCIENCE AND PSYCHIATRY

Thesis title: Hippocampal Subfield Volumes, Cognition, and Impulsivity in Suicidal Patients with Bipolar Disorder

Abstract Objective: Indirect evidence suggests that alterations of hippocampal structure influence or contribute to impulsivity and neuropsychological impairments associated with suicide attempts among persons with bipolar disorder. However, these suicide attempt-related associations in this clinical population require clarification. Methods: Neuropsychological function, impulsivity, and hippocampal subfield volumes were characterized in subjects with bipolar disorder and suicide attempts (BD-SA; N=50; 27 females), suicidal ideation without suicide attempts (BD-SI; N=50; 26 females), or no history of suicidal ideation or attempts (BD, N=50; 24 females), and in healthy comparison subjects (HC; N=120; 64 females). Results: Persons with bipolar disorder (all subgroups) had greater neuropsychological impairments, more impulsivity, and smaller hippocampal subfield volumes when compared to HC. The BD-SA group had more severe impairments of episodic memory, semantic fluency, and inhibition; greater attentional and motor impulsivity; and smaller CA2-3 and CA4-DG volumes than the BD-SI and BD groups. Among subjects with BD-SA, bilateral CA2-3 and CA4-DG volumes were inversely correlated with attentional and motor impulsivity scores. Furthermore, verbal memory and semantic fluency scores were directly correlated with bilateral CA2-3 and left CA4-DG volumes and inversely correlated with attentional and motor impulsivity scores. Conclusion: Among persons with bipolar disorder, suicide attempts, but not suicidal ideation, were associated with impaired memory and semantic fluency, greater impulsivity, and reduced hippocampal CA2-3 and CA4-DG subfield volumes. Multimodal assessments of the cognitive, behavioral, and neuroanatomic correlates of suicide might guide treatments aimed to reduce suicide risk in bipolar disorder.