Social Cognition, Memory, and Executive Functions in Bipolar Disorder and Major Depressive Disorder

Bipolar Disorders (BD) and Major Depressive Disorder (MDD) are two of the most common psychiatric disorders worldwide. BD is characterized by severe mood fluctuations (i.e., hypomanic/manic and depressive episodes) and can often be misdiagnosed as MDD, leading to delays in proper diagnosis. This is because the most common initial presentation of BD is a depressive episode. Such delays result in less appropriate care and support.

In addition to delayed diagnoses, the periods between symptomatic episodes, which are considered "stable," are not without challenges. Even during these euthymic periods, individuals often experience residual difficulties that impact their daily functioning. While these periods are viewed as symptom-free, it's clear that individuals still do not experience a significantly improved quality of life. Functional outcomes (e.g., occupational and social functioning) are often impaired and distinguishing between BD and MDD more clearly could improve care and enhance their quality of life. Identifying distinctive markers is essential for improving treatment strategies.

Cognitive functions might serve as trait markers of the disorders because they are impaired both during acute episodes and euthymic phases. These cognitive impairments could also predict functional outcomes in BD. Cognitive profiles may also help distinguish between BD and MDD. While impairments in executive functions, such as the ability to adapt to new situations (e.g., task-switching) and episodic memory (i.e., memory of specific personal events), are present even during euthymic phases of BD, this is not always the case for social cognition (e.g., facial emotion recognition). These cognitive alterations are highly heterogeneous across patients, and identifying their cognitive profiles could provide valuable insights.

Studying the links between cognitive components in BD and MDD may lead to a better understanding how cognitive functions are impacted in these mood disorders, and especially to understand the interactions between these different functions. Additionally, considering clinical symptomatology (e.g., the number of episodes) and other factors (e.g., anxiety, childhood trauma, social support) could offer a more comprehensive understanding of these disorders.

In addition to focusing on these two clinical populations, we will also include first-degree relatives of individuals with bipolar disorder. Indeed, it seems that these relatives may also experience mild cognitive impairments, and we aim to further investigate these hypotheses.

This project aims to better understand social cognition impairments (e.g., emotion processing, theory of mind, attribution bias) and their relationship with verbal episodic memory and executive functions (e.g., working memory, cognitive flexibility) in BD and MDD. It will also explore how these cognitive processes affect functional outcomes in these groups.

A first visit will be dedicated to the collection of clinical data. During the second visit, the investigators will conduct a comprehensive neuropsychological assessment to evaluate executive functions, episodic memory, and all components of social cognition. This protocol will allow the investigators to study all these variables together and to clarify and better understand the connections between them.

Inclusion criteria

• Patients between 18 and 65 years old, men or women
• Having a diagnosis of bipolar disorder or depressive disorder
• No substantial change in treatment for 2 weeks preceding study enrollment
• Being a native French speaker
• Patients enrolled in the national healthcare insurance program
• Consenting to participate to the study

Exclusion criteria

• The presence of any alcohol use disorder or any other substance use disorder in the last six months, except for tobacco dependence
• A significant general medical illness, including neurological disorders or head trauma
• A sensorial impairment uncorrected (visual and/or hearing)

Group 3: First-degree relatives of bipolar patients

Inclusion criteria

• Participants between 18 and 65 years old, men or women
• Participants having at least one first-degree relative presenting an bipolar disorder (parents, children, siblings)
• Being a native French speaker
• Patients enrolled in the national healthcare insurance program
• Consenting to participate to the study

Exclusion criteria

• A diagnosis of schizophrenia or of bipolar disorder or of depressive disorder according to DSM-5 criteria
• The presence of any alcohol use disorder or any other substance use disorder in the last six months, except for tobacco dependence
• A significant general medical illness, including neurological disorders or head trauma
• A sensorial impairment uncorrected (visual and/or hearing)

Group 4, 5, 6: Healthy control participants

Inclusion criteria

• Participants between 18 and 65 years old, men or women
• Being a native French speaker
• Patients enrolled in the national healthcare insurance program
• Consenting to participate to the study

Exclusion criteria

• A diagnosis of schizophrenia or of bipolar disorder or of major depressive disorder according to DSM-5 criteria
• The presence of any alcohol use disorder or any other substance use disorder in the last six months, except for tobacco dependence
• Participants having one first-degree relative presenting an bipolar disorder or depressive disorder or schizophrenia according to DSM-5 criteria
• A significant general medical illness, including neurological disorders or head trauma
• A sensorial impairment uncorrected (visual and/or hearing)