Characterizing the Neural Profiles of Bipolar Disorder with and without Auditory Hallucinations

BACKGROUND: Bipolar disorder (BD) is a psychiatric condition that affects ~2% of people. About a third of those with BD experience hearing voices in the absence of external sounds, or auditory hallucinations (AH), at some point during their illness. Hallucinations also occur in other mental disorders like schizophrenia. Regardless of the specific diagnosis, it appears that people who do vs. do not hear voices struggle more with daily living and are less likely to recover. While there is research on the effects of hallucinations in schizophrenia, they are poorly understood in BD. This work will clarify the impact of auditory hallucinations in BD on functioning, quality of life and suicide risk. It will assess how hallucinations impact the brain; this information will, in turn, inform better BD treatment. METHODS: We will recruit 46 people with BD who hear voices (BD/+AH) and 46 with BD who have never heard voices (BD/-AH) at two Canadian sites. We will compare brain electrical activity between groups using electroencephalography (EEG). We will study an EEG-derived marker of automatic sound processing called the MMN. The MMN has been shown to be reduced in people with schizophrenia, and more so in those who hear voices. As such, the MMN might be a brain-based marker of an illness feature. We will also conduct brain imaging to look at brain activity in regions involved in thinking and sound processing. We will obtain detailed descriptions of auditory hallucinations, and measure how they relate to brain features (i.e., linking brain features with clinical measures). IMPACT: This study will be the first to examine brain features of people with BD who hear voices, and their impact on daily life. Given the number of people with BD who experience voice hearing, this information is desperately needed, but is currently lacking. Such insights will help inform better interventions in the future, ultimately improving the lives of people living with BD.