Alzheimer’s disease (AD) is the most common subtype of dementia and is an irreversible, neurodegenerative brain disease of the older population. AD is characterised by the death of brain cells, which leads to a progressive decline in memory and cognitive abilities, including thinking, language and learning capacity. Due to the progressive nature of AD, common conditions in the elderly such as depression, diabetes, memory loss and anxiety are both risk factors and comorbidities for the disease. Among the multiple risk factors, major depressive disorder (MDD) is the most significant condition associated with AD, appearing at least ten years before the first clinical AD diagnosis.

According to a study conducted this month by Nedelac and colleagues and published in The Lancet Digital Health, MDD was significantly positively associated with an increased risk of AD in the UK and France. This was a large case-control study that examined French and British health records data from 20,000 patients with AD. MDD patients had a 1.30 and 1.70-times greater risk of developing AD in the UK and France, respectively, compared with the control group. AD patients had at least a ten-year history of MDD before the first clinical AD diagnosis.

MDD and AD are significant health burdens in the UK and France. GlobalData epidemiologists forecast that there were 310,000 AD diagnosed prevalent cases in the UK and 370,000 diagnosed prevalent cases in France last year. This is projected to increase to 360,000 diagnosed prevalent cases in the UK and 420,000 in France by 2028. GlobalData epidemiologists also forecast almost 5,000,000 12-month total prevalent cases of MDD in the UK and France by the end of this year. The increase in the number of cases of AD can be attributed to the projected increase in the elderly population in the respective markets during the forecast period and the high prevalence of associated conditions such as MDD.

The number of elderly persons surviving to the age of 80 years and older is expected to increase dramatically in the near future as advances in medicine and medical technologies increase life expectancy. This increase in the elderly population will, in turn, increase the number of persons living with AD, which will have a considerable impact on the healthcare systems in the respective countries, as well as on affected individuals, families, caregivers and society. Research suggests that the management of AD faces critical challenges worldwide for resources, funding and prioritisation by governments. It is, therefore, important to establish effective prevention strategies for AD, including further research into AD and associated conditions such as MDD.