Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that primarily affects individuals over 65 years old. It is the leading cause of dementia, accounting for 60–70% of cases.

AD is characterised by a gradual decline in cognitive function, impacting memory, language, and the ability to perform everyday activities.

Signs and Symptoms

The progression of Alzheimer's disease is generally divided into three stages: early, middle, and late.

First Symptoms

The earliest signs often include subtle memory loss and difficulty in learning new information. Patients may also exhibit apathy and mild depression.

These symptoms are frequently attributed to normal ageing or stress, delaying diagnosis.

Early Stage

In the early stage, significant memory impairment becomes apparent. Patients might struggle with language, experience perceptual difficulties, or find it challenging to perform complex tasks.

Despite these issues, they can still manage basic daily activities with some assistance.

Middle Stage

As the disease progresses, patients require help with most daily activities. Language problems intensify, and there is a marked decline in motor coordination and recognition of close relatives.

Behavioural changes, including irritability, aggression, and wandering, become more prevalent, leading to increased caregiver stress.

Late Stage

In the late stage, patients become entirely dependent on caregivers. Language abilities diminish to single words or phrases, and eventually, patients lose the ability to communicate.

Severe physical decline follows, often resulting in bedridden status and death typically due to infections or pneumonia.

Causes and Risk Factors

The exact cause of Alzheimer's is not well understood, but it involves a combination of genetic, environmental, and lifestyle factors. The strongest genetic risk factor is the presence of the APOEε4 allele.

Other risk factors include head injuries, hypertension, depression, and psychological stress.

Pathophysiology

Alzheimer's disease is marked by the accumulation of amyloid plaques and neurofibrillary tangles in the brain. These deposits disrupt neuronal function and connectivity, leading to brain atrophy.

Diagnosis

A probable diagnosis of Alzheimer's disease is made based on medical history, cognitive testing, and ruling out other conditions. Imaging techniques like CT, MRI, and PET scans can support the diagnosis by identifying characteristic brain changes.

Treatment

There is no cure for Alzheimer's disease, and treatments focus on managing symptoms. Medications include acetylcholinesterase inhibitors (such as donepezil) and NMDA receptor antagonists (like memantine).

These drugs provide modest symptomatic relief.

Non-pharmacological interventions, including cognitive therapies and physical exercise, can also help manage symptoms and improve quality of life. Caregiving remains a very important aspect of management, often placing significant emotional, physical, and financial burdens on caregivers.

Prevention and Lifestyle

Preventative measures are not well-established, but maintaining a healthy lifestyle may reduce the risk of cognitive decline. Physical exercise, mental activities, and social engagement are generally beneficial.

Managing cardiovascular risk factors such as hypertension, diabetes, and high cholesterol is also recommended.

Prognosis

The prognosis for Alzheimer's disease is poor, with an average life expectancy of three to twelve years following diagnosis. The disease progresses from mild cognitive impairment to severe disability and death, primarily due to secondary complications such as infections.

---

Self-assessment MCQs (single best answer)

What is the most common early symptom of Alzheimer's disease?

Which genetic factor is most strongly associated with an increased risk of Alzheimer's disease?

What type of protein accumulates to form amyloid plaques in the brains of Alzheimer's patients?

Which imaging technique is commonly used to support the diagnosis of Alzheimer's disease by identifying characteristic brain changes?

Which of the following medications is used to treat cognitive symptoms in Alzheimer's disease by inhibiting acetylcholinesterase?

Alzheimer's disease is characterised by the presence of which two abnormal structures in the brain?

What is the primary risk factor for developing Alzheimer's disease?

Which stage of Alzheimer's disease is characterised by complete dependence on caregivers and loss of verbal communication abilities?

What lifestyle factor is generally associated with a decreased risk of cognitive decline and Alzheimer's disease?

Which symptom is NOT commonly associated with Alzheimer's disease?