Alzheimer's disease is the most common cause of dementia, accounting for 60β80% of cases globally. Approximately 55 million people worldwide currently live with dementia, a figure projected to triple by 2050 as populations age. Alzheimer's is characterised by progressive neurodegeneration β the gradual loss of neurons and synaptic connections β leading to declining memory, cognition, language, and eventually the ability to perform basic daily activities. While no cure currently exists, early recognition, risk factor management, and newer disease-modifying therapies represent meaningful steps toward better outcomes.
Early Warning Signs
Normal ageing involves some slowing of processing speed and occasional memory lapses β forgetting a name momentarily, misplacing keys, taking longer to learn new technology. Alzheimer's presents differently: forgetting recently learned information (not just names) repeatedly; getting lost in familiar places; persistent confusion about dates, seasons, or the passage of time; trouble following conversations or finding words; changes in problem-solving or planning ability; withdrawal from social activities; and personality changes (increased anxiety, suspicion, or apathy). The Alzheimer's Association "10 Warning Signs" framework offers a practical screening tool for families concerned about a loved one's cognition.
Risk Factors and Prevention
Age is the greatest risk factor β prevalence roughly doubles every five years after 65. APOE Ξ΅4 β the most common genetic risk factor β increases lifetime risk approximately 3-fold in one-copy carriers and 8β12-fold in two-copy carriers, though many carriers never develop Alzheimer's. Modifiable risk factors collectively account for approximately 40% of global Alzheimer's cases. The most impactful: midlife hypertension, obesity, and hearing loss; later-life physical inactivity, depression, diabetes, smoking, and social isolation. A 2020 Lancet Commission identified 12 modifiable risk factors responsible for 40% of dementia cases. The FINGER trial demonstrated that a multidomain lifestyle intervention β diet, exercise, cognitive training, and cardiovascular risk management β significantly slowed cognitive decline in at-risk older adults.
Treatment
Acetylcholinesterase inhibitors (donepezil, rivastigmine, galantamine) modestly improve cognitive symptoms in mild-to-moderate Alzheimer's and are the standard first-line treatment. Memantine, an NMDA receptor antagonist, is added in moderate-to-severe disease. Neither class slows disease progression. Lecanemab and donanemab β newly approved anti-amyloid monoclonal antibodies β have demonstrated statistically significant slowing of clinical decline in early Alzheimer's in large phase 3 trials, representing the first genuine disease-modifying therapies; their clinical meaningfulness and optimal patient selection are actively debated.
Frequently Asked Questions
How is Alzheimer's different from normal ageing?
Normal ageing may slow retrieval speed and affect multitasking but does not impair the ability to learn new things, recognise familiar people, manage finances, or navigate familiar environments. Alzheimer's progressively impairs these capacities. If memory changes are causing concern or affecting daily function, formal neuropsychological evaluation is appropriate.
Is there a blood test for Alzheimer's disease?
Blood-based biomarkers β particularly plasma phosphorylated tau (p-tau217) and amyloid-beta ratios β have reached diagnostic accuracy comparable to CSF biomarkers and PET imaging in recent studies. FDA-cleared blood tests are now emerging for clinical use, with the potential to enable earlier diagnosis without invasive or expensive procedures. These tests are currently primarily used in research and speciality memory clinic settings.
Sources
- Alzheimer's Association. 2023 Alzheimer's Disease Facts and Figures.
- Livingston G, et al. Dementia prevention, intervention, and care. Lancet. 2020.
- WHO. Dementia fact sheet. 2023.