People with dementia who have comorbid severe mental illness (SMI), particularly bipolar disorder, experience a faster decline in cognitive performance than people without comorbid SMI. However, that decline was mitigated when antidepressants became part of models, researchers found in a study published in the American Journal of Geriatric Psychiatry. Sociodemographic behavior, health behavior, and cardiovascular risk factors also partly explained the faster decline, the researchers said.
The researchers used data from 4,718 people from south London and the Maudsley NHS (National Health Service) Foundation Trust (SLaM) Clinical Record Interact Search (CRIS) for populations from four boroughs in south London that are comparable to London in demographic factors. People had a primary or secondary diagnosis of dementia from 2007 to 2018, were at least 50 years old when they were first diagnosed with dementia, and had at least 3 MMSE (Mini-Mental State Examination) scores. The MMSE measures cognitive performance using 21 questions on orientation, immediate and delayed recall, naming, spelling and simple arithmetic and design practice.
Higher scores indicate better cognitive performance. The people included happened to have “slightly higher percentages” of Black and Caribbean, were married or lived together, and had a higher level of education. The drug data came from combined natural language processing (NLP) -derived data that mentioned or did not mention prescribed drugs in three categories: antipsychotics, antidepressants, and agents used to treat dementia.
Researchers used linear mixed models with random coefficients to examine group differences in cognitive trajectories, and examined associations using covariates and sensitivity analyzes. They compared the models that contained an unknown category when missing values for a covariate were greater than 30% with cases with complete information. The researchers also performed an analysis narrowing the sample to the 1,766 people still alive in 2019 in order to review and compare possible biases associated with premature mortality among people with SMI.
The researchers found that people with comorbid dementia and SMI (20.8, standard deviation (SD): 6.3) had higher MMSE values than people with only dementia (19.7, SD: 6.2, P <0 , 05 for both). Current smokers, people at risk for cardiovascular disease, or people taking dementia or antipsychotics had lower MMSE levels compared to people who have never smoked, were not considered patients at risk Classified for cardiovascular disease (CVD) and not taking dementia or antipsychotics. While the cognitive decline seemed to accelerate faster in people with bipolar disorder compared to people with dementia, people with schizophrenia had similar courses to people with only dementia.
Adjusted for socioeconomics, smoking, CVD risk, and all drugs, the slope of the MMSE trajectories for people with dementia and SMI was -0.133 (0.061). [95% confidence interval (CI) [-0.252, -0.014]]. Before adjusting all drugs, only dementia drugs had a slope estimate of -0.152 (0.058). [95% confidence interval (CI): -0.286, -0.057](P <0.01) for the cognitive trajectory with antipsychotic drugs only with a slope estimate of -0.144 (0.061) [95% CI: -0.264, -0.025](P <0.05) and with only antidepressants -0.19 (0.059)[95% CI: -0.306, -0.075](P <0.01).
Limitations of the study included data on health behaviors that are restricted to smoking status and potential selection biases associated with restricting the sample to those with at least 3 available MMSE scores, as dementia cannot be diagnosed in SMI.
“In terms of drugs, adjusting for dementia, antipsychotic, and antidepressant drugs had a large impact on the association of interest, even after taking into account the other covariates taken into account, such as CVD risk,” the authors said.
“When we examined the role of each drug independently, we found that this impact was clear for dementia and antidepressants. The estimates suggest that antipsychotics may have a greater and potentially protective impact in bipolar disorder.”
Disclosure: Several authors of the study have declared their affiliations with the industry For a full list of the authors’ information, see the original reference.
Bendayan R., Mascio A., Stewart R., Roberts A., Dobson R. Cognitive trajectories in comorbid dementia with schizophrenia or bipolar disorder: The case register of the Trust Biomedical Research Center (SLaM BRC) of the NHS Foundation in South London and Maudsley. Am J Geriatric Psychiatry. Published online on November 6, 2020. doi: 10.1016 / j.jagp.2020.10.018
This article originally appeared on Psychiatry Advisor