A study led by researchers at the University of Oulu and the University of Eastern Finland found that people who develop Alzheimer's disease before age 65 accumulate a wide range of health problems in the years before they are diagnosed. The clearest pattern appeared in the five years leading up to diagnosis, when these patients were more likely than matched controls to have depression, dizziness, headaches, traumatic brain injuries, epilepsy, cerebrovascular disorders, thyroid diseases and problems related to heavy alcohol use. Tinnitus and hearing loss were already more common six to ten years before diagnosis.
The most notable result concerned heart and circulation risks. Cardiovascular risk factors such as high blood pressure and hyperlipidemia, which are closely linked to late-onset Alzheimer's, were not more common among people with early-onset disease than among the control group. That contrast is central to the researchers' argument that early-onset disease may not be simply a younger version of the late-onset form.
The team looked at health conditions during the 15 years before diagnosis. They found no significant differences in morbidity 11 to 15 years out, which suggests that detectable changes emerge mainly closer to disease onset. Healthcare use rose sharply over the five years before diagnosis, with the steepest jump in visits during the final year.
Adjunct Professor Johanna Kruger, the study's lead investigator, said the results support the view that early-onset Alzheimer's is not simply a younger-age version of the late-onset disease. The researchers stressed that no single symptom predicts the disease. Instead, patients may show a scattering of seemingly unrelated complaints and clinic contacts, and recognizing that broader pattern could prompt earlier suspicion of a neurodegenerative condition.
The findings draw on memory clinic records from Oulu University Hospital and Kuopio University Hospital, combined with nationwide health register data. The study included 407 people with early-onset Alzheimer's and compared them with more than 4,000 age- and sex-matched controls. The authors note that diagnosing early-onset disease is often delayed by several years after first symptoms, which is why they argue for identifying it earlier among working-age adults.