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Doctoral defence of Blair Rajamaki, MSc, 26 April 2024: Attention to comorbidities in the care of Alzheimer’s disease

The doctoral dissertation in the field of Neurology will be examined at the Faculty of Health Sciences at Kuopio campus. The public examination will be streamed online.

What is the topic of your doctoral research? Why is it important to study the topic?

Finland has one of the highest prevalence of Alzheimer’s disease diagnoses in the European Union and the numbers are predicted to increase with the aging population. There is no cure for Alzheimer’s disease and current pharmacological treatments may only control the disease symptoms. Co-morbid illnesses, such as cardiovascular disease, are also common in older adults, but it is unclear how these comorbid conditions affect adverse outcomes (e.g., survival time, length of hospital stays, and hospital readmissions). This information is vital for societies to plan and provide appropriate care for this vulnerable population. This doctoral thesis investigated differences in patterns of comorbidities and health outcomes between persons with and without Alzheimer’s disease in Finland.

What are the key findings or observations of your doctoral research?

Utilizing a technique from Natural language processing we were able to successfully apply it to clustering of diagnosis codes in an epidemiological study. Early signs and symptoms that are associated with Alzheimer’s disease were only found in the clusters of the Alzheimer's disease cohort, but not the controls. Health outcomes of people with and without Alzheimer’s disease were found to vary. Comorbidities were related to higher mortality in persons with and without Alzheimer’s disease. However, Alzheimer's disease had the greatest effect on survival. Short hospital stays in an acute care setting for a hip fracture were associated with an increased risk of readmission within 30 days of discharge for both people with and without Alzheimer’s disease.

How can the results of your doctoral research be utilised in practice?

Using techniques from natural language processing on register-based data may be helpful in finding hidden patterns in comorbid diagnoses. Appropriate management of care for comorbidities may increase survival time and the overall well-being of people with AD. To improve the health of persons with Alzheimer’s disease it would be important to focus also on comorbidities. Longer hospital stays after hip fracture may be beneficial by allowing time for comprehensive geriatric assessments that could identify and initiate treatments for potential complications, like infections and delirium, potentially leading to better health outcomes and decreasing costly hospital readmissions.

What are the key research methods and materials used in your doctoral research?

This thesis is based on the Medication use and Alzheimer’s disease study (MEDALZ), which uses register-based data from multiple health registers. The study included community dwellers newly diagnosed with Alzheimer’s disease in Finland during 2005-2011 (N= 70,718). These people were identified from a nationwide Special Reimbursement Register, including reimbursement data for chronic diseases, such as AD. Comparison persons without AD were identified and matched for age, sex, and region of residence. Data on comorbidities and hospital days were identified from the Care Register for Health Care, including both inpatient stays and outpatient visits in specialized healthcare. Other sources for identifying comorbidities were the Special Reimbursement Register and the Prescription Register. 

Latent Dirichlet allocation, a technique from natural language processing, was used to model cluster patterns of comorbidities between people with and without AD, and both quantitative and qualitative analyses were performed. This type of model has not previously been used in register-based studies like ours. Using the high-quality health registers allowed for a long follow-up time of 11 years when assessing survival risk and captured data on a nationwide level. 

The doctoral dissertation of Blair Rajamaki, MSc, entitled Comorbidities, mortality, and hip fracture outcomes among persons with Alzheimer's disease: A Finnish nationwide register-based study will be examined at the Faculty of Health Sciences. The Opponent in the public examination will be Professor Maria Eriksdotter of Karolinska Institutet, and the Custos will be Professor Anna-Maija Tolppanen of the University of Eastern Finland.

Doctoral defence 


For further information, please contact:

Blair Rajamaki, MSc, blair.rajamaki(a), +358505765438,