For years, high blood pressure and high cholesterol have been recognised as important risk factors for Alzheimer’s disease. But new research suggests that people who develop the disease before age 65 may follow a different path, experiencing a range of seemingly unrelated health problems long before their diagnosis.

A study by researchers at the University of Oulu and the University of Eastern Finland found that people with early-onset Alzheimer’s disease were more likely to develop several health conditions in the years preceding diagnosis. These included depression, dizziness, headaches, traumatic brain injuries, epilepsy, cerebrovascular disorders, thyroid diseases and problems associated with heavy alcohol use. Hearing loss and tinnitus were also more common six to ten years before diagnosis.

One of the most surprising findings was the absence of a stronger association with traditional cardiovascular risk factors. Unlike late-onset Alzheimer’s disease, high blood pressure and elevated cholesterol levels were no more common among people with early-onset Alzheimer’s than among individuals of similar age and sex without neurodegenerative disease. The findings challenge conventional assumptions about the factors associated with Alzheimer’s disease.

The researchers examined health records covering the 15 years before diagnosis. They found few significant differences between the groups during the earliest period, 11 to 15 years before diagnosis. However, health problems became increasingly common as diagnosis approached, particularly during the final five years. This suggests that early-onset Alzheimer’s may have a distinct clinical profile rather than simply representing an earlier version of the disease typically seen in older adults.

“Our findings support the view that early-onset Alzheimer’s disease is not simply a younger-age version of late-onset Alzheimer’s disease. Rather than the familiar cardiovascular risk factors, we observed a range of other health problems becoming more common as diagnosis approached,” said Johanna Krüger, adjunct professor at the University of Oulu and the study’s lead investigator.

The study also revealed a sharp rise in healthcare use during the five years before diagnosis. Patients increasingly sought medical attention for various conditions, with healthcare visits rising most dramatically during the final year. Researchers believe this pattern of repeated medical encounters, combined with accumulating health problems, could provide valuable clues for identifying the disease earlier.

“No single disease or symptom predicts Alzheimer’s disease,” cautioned Laura Leppänen, a doctoral researcher at the University of Oulu and the study’s first author. However, she explained that recognising a combination of seemingly unrelated symptoms and increasing healthcare visits could prompt doctors to investigate possible neurodegenerative disease sooner. Earlier recognition is particularly important because Alzheimer’s disease in working-age adults can be difficult to identify, often resulting in diagnostic delays lasting several years.

The findings were based on patient records from memory clinics at Oulu University Hospital and Kuopio University Hospital, linked with nationwide Finnish health registers. Researchers compared 407 people diagnosed with early-onset Alzheimer’s disease with more than 4,000 age- and sex-matched controls. The study highlights the importance of looking beyond conventional cardiovascular risk factors and recognising broader patterns of health changes that may precede an Alzheimer’s diagnosis.

More information: Laura Leppänen et al, Comorbidities and health-care use prior to early-onset Alzheimer’s disease: A population-based case–control study, Alzheimer’s & Dementia. DOI: 10.1002/alz.71831

Journal information: Alzheimer’s & Dementia Provided by University of Oulu, Finland