Summary: Poor verbal memory may increase the risk of psychiatric hospitalization for patients diagnosed with bipolar disorder or depression. The severity of the illness was previously thought to have an impact on poor memory, but the study shows that poor memory may also have an impact on the risk of being hospitalized.
Findings reveal there is an approximately 84% increased risk of being admitted to a psychiatric ward if a patient has previously had clinically significant impairments in verbal memory.
- A new study has found that verbal memory can determine whether psychiatric patients diagnosed with bipolar disorder or depression are at risk of being hospitalized or readmitted to a psychiatric ward.
- The study followed 518 patients over a number of years and found that poor verbal memory in itself increases the risk of psychiatric hospitalization, with an approximately 84% increased risk of being admitted to a psychiatric ward if one has previously had a clinically significant impairment in the ability to learn and remember verbal information.
- The researchers recommend that more attention should be paid to impaired memory in psychiatric treatment and that new treatment approaches are needed to help address the persistent memory and cognitive problems faced by around half of the patients with recurrent depression or bipolar disorder.
Source: University of Copenhagen
Memory plays a crucial role in people’s social and working lives. Now, new research shows that verbal (i.e. linguistic) memory also determines whether psychiatric patients diagnosed with bipolar disorder or depression are at risk being hospitalized or readmitted to a psychiatric ward.
“It has long been known that patients who have previously been hospitalized with major depression or bipolar disorder often have impaired memory. But it was believed that it was the severity of the illness itself that played a role in the poor memory. Now we can see that the arrow also points the other way,” says Kamilla Miskowiak, professor at the Department of Psychology at the University of Copenhagen.
In the new study, Kamilla Miskowiak, in close collaboration with senior researcher Anjali Sankar and a number of other researchers from the Neurobiological Research Unit at Rigshospitalet and the UCPH, followed 518 patients over a number of years, all of whom have previously undergone the same cognitive tests in other studies.
Combined with data from Statistics Denmark, the researchers have used the previous studies to see to what extent the patients’ verbal memory and so-called executive functions, such as the ability to plan and problem-solve, affect the risk of being hospitalized in a psychiatric ward.
The conclusion is clear:
“Poor verbal memory in itself increases the risk of psychiatric hospitalization. This is evident when we adjust for previous hospitalization, severity of illness, depression symptoms and other factors that we know are important,” explains Kamilla Miskowiak.
Nearly double the risk of hospitalization
The study concludes that there is an approximately 84 percent increased risk of being admitted to a psychiatric ward if you have previously had a clinically significant impairment in the ability to learn and remember verbal information.
The study cannot say for sure why this verbal memory impairment increases the risk. But according to Kamilla Miskowiak, it may be related to the fact that patients often find it more difficult to remember their medication and to keep up with the demands of their everyday life, which in turn can lead to stress.
“We know that stress is a major risk factor for relapse. And many people with mental health problems are already struggling to stay afloat. So being exposed to the additional stress of verbal memory impairment can increase the risk of new severe depressions or manias that require hospitalization.”
Conversely, the study finds no significant association between impaired executive function and increased risk of hospitalization. And patients with impaired cognitive function do not appear to fare significantly worse on social parameters such as employment, cohabitation and marital status.
However, the researchers found that poor executive function was associated with a 51 percent reduced likelihood of having achieved the highest level of education (polytechnic and university). Reduced ability to plan and implement problem-solving strategies during studies may hamper educational achievement and vice versa, says Kamilla Miskowiak.
Call for new treatment methods
But above all, it is key knowledge that poor verbal memory itself increases the risk of psychiatric hospitalization among people with mental illness. According to Kamilla Miskowiak, this means that more attention should be paid to impaired memory in psychiatric treatment, which currently has a limited focus on cognitive skills.
“It is not enough just to treat patients’ symptoms of depression or mania, for example. We also need to work on strengthening their memory and other cognitive functions as soon as they are symptom stable,” she says.
“About half of patients with recurrent depression or bipolar disorder have persistent problems with memory and other cognitive functions. This calls for both more systematic cognitive screening and new treatment approaches.”
About the study
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 hospitalizations 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 hospitalization and worsening social conditions.
First author Anjali Sankar, a senior researcher at Rigshospitalet’s research unit NRU, has been the main force behind most of the analyses in collaboration with project manager Kamilla W. Miskowiak. 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.
Funding: 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.
About this memory and mental health research news
Original Research: Open access.
“Association of neurocognitive function with psychiatric hospitalization and socio-demographic conditions in individuals with bipolar and major depressive disorders” by Kamilla Miskowiak et al. EClinicalMedicine
Association of neurocognitive function with psychiatric hospitalization and socio-demographic conditions in individuals with bipolar and major depressive disorders
Neurocognitive impairments are associated with poor clinical and employment outcomes in individuals with affective disorders. However, little is known about their associations with long-term clinical outcomes such as psychiatric hospitalizations, and with socio-demographic indicators other than employment. In the largest longitudinal study of neurocognition in affective disorders to date, we investigate the role of neurocognitive impairments on psychiatric hospitalizations and socio-demographic conditions.
The study included 518 individuals with bipolar or major depressive disorder. Neurocognitive assessments covered executive function and verbal memory domains. Longitudinal data on psychiatric hospitalization and socio-demographic conditions (employment, cohabitation, and marital status) for up to 11 years were obtained using National population-based registers. The primary and secondary outcomes were psychiatric hospitalizations (n = 398) and worsening of socio-demographic conditions (n = 518), in the follow-up period since study inclusion, respectively. Cox regression models were used to examine the association of neurocognition with future psychiatric hospitalizations and the worsening of socio-demographic conditions.
Clinically significant impairment in verbal memory (z-score ≤ −1; defined by the ISBD Cognition Task Force), but not in executive function, was associated with a higher risk of future hospitalization, when adjusted for age, sex, hospitalization in the year preceding inclusion, depression severity, diagnosis, and type of clinical trial (HR = 1.84, 95% CI:1.05–3.25, p = 0.034; n = 398). The results remained significant even after accounting for illness duration. Neurocognitive impairments were not associated with the worsening of socio-demographic conditions (p ≥ 0.17; n = 518).
Promoting neurocognitive function, especially verbal memory, may mitigate the risk of future psychiatric hospitalization in individuals with affective disorders.