News — Recollection has a pivotal function in individuals' professional and social existence. Presently, fresh investigations display that the ability to remember words (i.e. linguistic memory) additionally establishes if individuals with bipolar disorder or depression undergoing psychiatric treatment may face the possibility of hospitalization or re-admittance to a psychiatric facility.

Kamilla Miskowiak, a professor at the University of Copenhagen's Department of Psychology, states, "The fact that memory is impaired in patients who were previously hospitalized for major depression or bipolar disorder has been well-established for some time. However, it was previously thought that the illness's severity was the sole factor contributing to this memory impairment. Now, we can observe that the relationship between memory and psychiatric illness is bidirectional."

During the recent research, Kamilla Miskowiak, in conjunction with senior researcher Anjali Sankar and several other researchers from the Neurobiological Research Unit at Rigshospitalet and UCPH, monitored 518 patients for several years. All of these individuals had previously taken part in cognitive assessments for other research studies.

By incorporating data from Statistics Denmark, the researchers utilized the earlier studies to examine how patients' linguistic memory and executive functions, which involve skills such as planning and problem-solving, influenced their likelihood of being admitted to a psychiatric ward.

The conclusion is clear:

Kamilla Miskowiak clarifies, "Even after accounting for previous hospitalization, illness severity, depressive symptoms, and other important factors, having a weak linguistic memory independently raises the risk of being hospitalized for psychiatric reasons."

Nearly double the risk of hospitalisation

According to the study's findings, there is an approximately 84% greater likelihood of being admitted to a psychiatric ward if an individual has previously experienced clinically significant difficulties with learning and retaining verbal information.

Although the study did not identify a definitive reason why verbal memory impairment raises the risk of psychiatric hospitalization, Kamilla Miskowiak suggests that this may be linked to patients' challenges in remembering their medication and managing daily responsibilities, leading to increased stress levels.

Kamilla Miskowiak explains, "Stress is a significant risk factor for relapse, and individuals with mental health issues often struggle to manage daily tasks. Therefore, being confronted with the added stress of verbal memory impairment can increase the likelihood of experiencing new episodes of severe depression or mania, which may necessitate hospitalization."

On the other hand, the study did not find a notable correlation between executive function impairment and an elevated risk of hospitalization. Furthermore, patients experiencing cognitive impairments did not seem to experience significant disadvantages in social aspects such as employment, cohabitation, and marital status.

Despite the lack of a significant association between impaired executive function and hospitalization risk, the study did identify a correlation between reduced executive function and a 51% lower probability of obtaining higher education, such as a polytechnic or university degree. Kamilla Miskowiak suggests that difficulties with planning and implementing problem-solving strategies during academic pursuits may impede educational attainment and vice versa.

Call for new treatment methods

Despite the lack of a significant association between impaired executive function and hospitalization risk, the study did identify a correlation between reduced executive function and a 51% lower probability of obtaining higher education, such as a polytechnic or university degree. Kamilla Miskowiak suggests that difficulties with planning and implementing problem-solving strategies during academic pursuits may impede educational attainment and vice versa.

Kamilla Miskowiak emphasizes that it is insufficient to only address patients' depression or mania symptoms. Instead, efforts should also be made to enhance their cognitive functions, such as memory, once they have achieved symptom stability.

Kamilla Miskowiak notes that around 50% of patients experiencing recurrent depression or bipolar disorder experience persistent cognitive function problems, including memory impairment. As a result, there is a need for more structured cognitive assessment and new treatment strategies.

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About the study

The study titled 'Association of neurocognitive function with psychiatric hospitalisation and socio-demographic conditions in individuals with bipolar and major depressive disorders', is published in the Lancet journal eClinicalMedicine.

The study, the largest of its kind to date, includes a total of 518 patients diagnosed with either bipolar disorder or depression. Studies follow the development of patients from 2009 to 2020, using registry data on hospitalisations and including a range of demographic and socio-economic variables such as age, gender, education and employment.

As all participants have undergone the same cognitive tests before entering the study, statistical analyses can assess the extent to which impaired verbal memory and executive functioning (including planning and problem solving) increase the risk of psychiatric hospitalisation and worsening social conditions.

First author , a senior researcher at Rigshospitalet's research unit NRU, has been the main force behind most of the analyses in collaboration with project manager . In addition, eight other researchers affiliated with the University of Copenhagen and Rigshospitalet have been involved in the study: Simon C. Ziersen, Brice Ozenne, Emily E. Beaman, Vibeke H. Dam, Patrick M. Fisher, Gitte M. Knudsen, Lars V. Kessing og Vibe Frøkjær.

The study is part of a larger project, BrainDrugs, which is led by Professor Gitte Moos Knudsen and has received funding from the Lundbeck Foundation.