what is Alzheimer’s Disease? its causes, symptoms and treatment.

Author: Josna Lewis

Alzheimer’s Disease

Introduction

Alzheimer’s disease is a neurodegenerative, chronic disorder that worsens with time. It is a type of dementia. Mainly due to the deposition of proteins (β amyloid plaques and tau protein). Characterised by impaired memory, speech, and thinking ability.

Globally 50 million people are estimated to currently have dementia, and 10-12% of older Americans are prone to Alzheimer’s disease (AD) and cognitive deficits. The prevalence of AD progresses with age among the older population (>65 years of age) and 70% have late onset. On the contrary, if it is seen in a population < 65 years, it is termed early onset Alzheimer’s.

There is no cure, but symptoms can be managed with therapies.

What is Dementia?

Dementia is a syndrome underlying various diseases that damage the nerve cells and decline in signal transmission, in turn leads to deterioration of cognitive abilities i.e. from forgetting a recent event to severe dementia to difficulty in performing daily activities. Alzheimer’s is a type of dementia.

What is Alzheimer’s Disease

It is a progressive deterioration of the brain and brain cells that leads to a decline in cognitive and other bodily functions. The most common type of AD is late-onset Alzheimer’s occurs in a population in the 60s and greater age population, early-onset Alzheimer’s occurs in the population in the 30s to 60s and is rare.

What is the Cause?

The human brain is composed of over 100 billion nerve cells and they signal and communicate all the activities for the normal functioning of the system.

There are many causes likely, age, genetic factors, head injury, oxidative damage, infections, lifestyle and other environmental factors and underlying diseases. There still proposed hypotheses as a cause for AD are cholinergic impairment and Amyloid β/ tau protein accumulation.

Cholinergic Hypotheses, Acetylcholine is involved in memory, sensory, learning, and other crucial functions in the brain, and degeneration of Ach is observed in people with AD due to lack reuptake of choline and release of Ach.

In amyloid β plague, the degradation of amyloid β (soluble proteins) decreases with age or pathological condition, and accumulation of the abnormal large deposits of amyloid β extracellularly as amyloid plague (insoluble protein).

Tau protein, these soluble proteins maintain the stability of microtubules and axons and are abundant in neurons. In AD the tau protein changes into insoluble intracellular neurofibrillary tangles and damages the neuronal cells. Thus, change in protein clearance is age-related and lead to neuronal death and neurodegenerative diseases.

What are the Signs and Symptoms

In Alzheimer’s symptoms are gradually seen and worsen over time since it is a progressive neurodegenerative disorder. There are three stages early, mild, moderate, and severe. The pivotal and first symptom is memory loss which may worsen with time.

Symptoms include

Memory Loss:

• Starts with remembering the recent event (short-time memory loss)
• Difficulty in taking new information
• Repetitive questioning
• Anomia (lack of ability to identify his/ her objects)

Cognitive deficits

• Lack of reasoning ability
• Example: misplacing objects, forgetting conversations, problems remembering names, and missing appointments)
• Disoriented speech
• Alexia (decline in understanding or framing common spellings, and sentences).
• Lack of intellectual ability
• Difficulty in deciding on own

Neurological signs

• Disorientation, confusion, mood change
• Aggression, agitation
• Gait abnormalities in AD than the normal aging
• Delusions and hallucinations in later stages.

Most of the symptoms exhibited in AD are also seen in normal aging and would be difficult to distinguish.

Stages of Alzheimer’s disease

Clinicians classified AD into 4 stages

Preclinical Stage

Changes in the brain begin years before showing clinical symptoms. Here no apparent symptoms are seen and this stage may last for years. And maybe have episodic memory impairments.

Early Stage or Mild cognitive impairment

Appearance of first symptoms i.e. short-term memory, intermitted memory lapse. In turn be mistaken due to aging. People with MCI may experience memory lapses for information that is typically easy to recall. This may include conversations, recent events or daily activities. Mild impairment in speech and visual interpretation.

Moderate Impairment

Significant deterioration of memory, verbal, writing and visual interpretation. Gradually develop delusions and hallucinations in a few patients. Patients may also lose emotional control and develop aggressive tantrums, restless activities, these need supervision and caretakers.

Severe Impairment

Severe cognitive deficits, difficulty in interpreting even simple words, and phrases, and require assistance to self. Certain populations might also express aggressive behavior, and gradually develop extrapyramidal effects. Life expectancy is reduced to one-third, and old age, severe symptoms, and illness are the major risk factors.

What is the Treatment?

There is no cure for Alzheimer’s, but symptoms can be controlled or provided with cognitive enhancers.

Medications to treat cognitive symptoms of Alzheimer’s are acetylcholinesterase inhibitors (tacrine, rivastigmine galantamine, donepezil), and NMDA antagonists (memantine).

Acetylcholinesterase inhibitors are used in mild to moderate Alzheimer’s and enhance cholinergic neurotransmission and mitigate cognitive impairment.

NMDA antagonist (memantine) used in moderate to severe Alzheimer’s, inhibits excitatory glutamatergic neurons (cause brain cell damage) and inhibits overstimulation of glutamate.

Aducanmab, a monoclonal antibody (inhibits amyloid β protein) an intravenous infusion for mild to moderate cognitive impairment and mild dementia due to AD.

Lecanemab, a monoclonal antibody for mild Alzheimer’s or cognitive impairment, phase 3 trial showed that medicine slowed cognitive decline and prevented clumping of amyloid plagues. Side effects are seen and people taking lecanemab might have swelling in the brain but rarely became severe. It is recommended to get an MRI before starting the treatment.

Moreover, take care of your physical health,

• Seek help from your family, ask for help.
• Get regular checkups, be open with your physician.
• Have a routine diet and exercise.
• Rest well when tired
• Consult your physician if you are considering changing your medication.
• Consider your emotional and psychological health.

Conclusion

Alzheimer’s disease is a complex, chronic disease. Despite the challenge to patients, families and healthcare providers, though there is no cure there are various mitigations used in the treatment and manage symptoms and improve the quality of life. There are medications used to mitigate the symptoms and the research is going on for the better treatment. Beyond pharmaceutical care it is important to have physiological, emotional, and psychological care. It is only through the multifaceted approach we can manage the devasting disease. Future holds breakthroughs, through personalized medicine and other advancements in treatment.