An Overview of Alzheimer’s Disease

INTRODUCTION

Alzheimer’s disease, a neurodegenerative disease, is the most common cause of dementia. Dementia is a broader term for conditions caused by brain injuries or diseases that negatively affect memory, thinking, and behavior. These changes interfere with daily living. Dementia is a clinical syndrome characterized by progressive decline in two or more cognitive domains, including memory, language, executive and visuospatial function, personality, and behavior, which causes loss of abilities to perform important and/or basic activities of daily living.

PREVALENCE

Exact estimates of the prevalence of dementia depend on the definition and specific threshold used. Dementia affects approximately 5%-8% of individuals over age 65, 15%- 20% of individuals over age 75, and 25%-50% of individuals over age 85 [1]. Alzheimer’s disease is the most common cause of dementia, accounting for 50%-75% of the total, with a greater proportion in the higher age ranges.

SYMPTOMS

Some common symptoms of Alzheimer’s disease are:

1. Memory loss that disrupts daily life
2. Challenges in planning or problem solving
3. Difficulty completing familiar tasks like driving to a familiar location, organizing a grocery list or remembering the rules of a favorite game
4. Trouble understanding visual images and spatial relationships like difficulty with balancing and difficulty judging distances
5. Confusion with time or place i.e. sometimes people suffering from Alzheimer’s disease forget where they are or how they got there
6. Problems with words in speaking or writing i.e. people suffering from Alzheimer’s disease may have trouble following conversations or taking part in them

CAUSES

Although the exact causes of Alzheimer’s disease are not known, it is believed that it is caused by the abnormal build-up of proteins in the brain. There are two major proteins involved.

One of them is called ‘β-amyloid’ and deposits of this protein form plaques (plate-like structures) in the brain. The other one is called ‘tau’, deposits of which form tangles in the brain. This process starts years before actual presentation of symptoms [2].

However, there are many risk factors that do not cause the disease directly but increase an individual’s chance of being diagnosed. Some of the risk factors associated with Alzheimer’s disease are

1. Age: This is the single most important risk factor. The chance of being diagnosed doubles every 5 years after the age 65
2. Family history: Though having a family history does not mean you will have it for sure, genetics do play a key role in increasing the chances of getting it
3. Down’s Syndrome: People having Down’s Syndrome are at a higher risk [6]

DIAGNOSIS

Doctors have to determine whether a patient has ‘possible Alzheimer’s disease’ (where dementia can be due to other causes) or ‘probable Alzheimer’s disease’ (where no other cause for dementia is found). To differentiate between these, following tests could be performed:

1. Tests of memory, problem solving, attention, counting, and language
2. Blood and urine tests
3. Brain scans, such as computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET)

Doctors also need to understand the patient’s medical history and extent of symptoms faced in the recent past. The above tests may also be repeated to understand the changes over time. Using these methods, a Doctor can diagnose Alzheimer’s Disease to an accuracy of 90%. However, a definite diagnosis of Alzheimer’s disease can only be obtained after the death of the patient using tissues from the brain taken from post-mortem [3].

TREATMENT

Although current Alzheimer’s treatments cannot stop Alzheimer’s from progressing, they can temporarily slow the worsening of dementia symptoms and improve quality of life for those with Alzheimer’s and their caregivers.

Medications for memory and cognition

Cholinergic systems in the brain are affected in the early stages of the disease. This can negatively impact memory and cognitive functioning. Cholinergic inhibitors (CI) treatment can be used to enhance cholinergic transmission and slow down the degradation of neurons associated with the cholinergic system. Another drug called memantine is believed to protect neurons from excitotoxicity. Studies have shown improvements in cognition, activities of daily living (ADL), and behaviours in people with Alzheimer’s disease [4].

Treatments for behaviour

Progressive deterioration of brain cells, medications, and environmental changes like triggering situations can cause behavioural changes in patients. This can be treated through non-drug therapy or drug therapy. Non-drug therapy includes keeping the patient physically and emotionally comfortable. Monitoring personal comfort, avoiding being confrontational, creating a calm environment, etc. are some examples of coping tips that are part of non-drug therapy.

Introducing medications may be appropriate for people with extreme symptoms, who are at risk of harming themselves. Although there are no FDA approved drugs for treatment of behavioural symptoms, antidepressants (for low mood and irritability), anxiolytics (for anxiety, restlessness, verbally disruptive behavior and resistance), and antipsychotic medications (for hallucinations, delusions, aggression, agitation, hostility and uncooperativeness) [5].

SUMMARY

Alzheimer’s disease is a neurodegenerative condition which causes memory loss and cognitive decline. Even though there is no definite diagnosis, Doctors can accurately diagnose the condition by considering many factors. Currently, the disease cannot be reversed, but there are many ways to slow its progression and manage symptoms.

REFERENCES

1. Béatrice Duthey. “Priority Medicines for Europe and the World: A Public Health Approach to Innovation”, WHO Background Paper, Feb 2013
2. Schachter, A S, and K L Davis. “Alzheimer’s disease.” Dialogues in clinical neuroscience vol. 2,2 (2000): 91–100
3. https://www.nia.nih.gov/health/alzheimers-disease-fact-sheet#diagnose
4. Yiannopoulou, Konstantina G, and Sokratis G Papageorgiou. “Current and future treatments for Alzheimer’s disease.” Therapeutic advances in neurological disorders vol. 6,1 (2013): 19–33. doi:10.1177/1756285612461679
5. https://www.alz.org/alzheimers-dementia/treatments/treatments-for-behavior
6. https://www.alz.org/alzheimers-dementia/what-is-alzheimers/causes-and-risk-factors