Alzheimer’s disease

In today’s world, neurodegenerative diseases (NDs) pose a major threat to public health, and they are considered to be the most debilitating disorders affecting the human population.

One reason for this is the fact that despite great advances in neuroscience, no cure for NDs has been found yet. The progression of NDs leads to speech and movement impairment, memory loss, and cognitive decline. These symptoms exert an immense emotional and financial burden on affected individuals, their families, and society as a whole.  

In recent times, NDs have become the fourth leading cause of death after heart disease, cancer, and stroke (Rai et al., 2019). The prevalence of NDs, particularly Alzheimer’s disease (AD) and Parkinson’s disease (PD), is predicted to increase significantly in the coming years. Although recent research has helped us in understanding the initial triggers of NDs as well as the potential factors that contribute to neuronal death, clear mechanisms underlying neuro degeneration are yet to be discovered.  

Alzheimer’s disease
Alzheimer's disease is a degenerative brain disorder of unknown etiology which is the most common form of dementia that usually starts in late middle age or in old age, results in progressive memory loss, impaired thinking, disorientation, and changes in personality and mood. There is degeneration of brain neurons especially in the cerebral cortex and presence of neurofibrillary tangles and plaques containing beta-amyloid cells. 

Origin of Alzheimer's disease the disease was first described by Dr. Alois Alzheimer, a German physician, in 1906. Alzheimer had a patient named Auguste D, in her fifties who suffered from what seemed to be a mental illness.  

But when she died in 1906, an autopsy revealed dense deposits, now called neurotic plaques, outside and around the nerve cells in her brain. Inside the cells were twisted strands of fibre, or neurofibrillary tangles. Since Dr. Alois Alzheimer's was the first person who discovered the disease, AD was named after him. Auguste D.  

Alzheimer’s disease is a chronic, irreversible disease that affects the cells of the brain and causes impairment of intellectual functioning. Alzheimer's disease is a brain disorder which gradually destroys the ability to reason, remember, imagine, and learn. 

About 3 percent of men and women ages 65 to 74 have AD, and nearly half of those age 85 and older may have the disease. About 3, 60,000 new cases of Alzheimer’s are diagnosed each year. 

Stages and major symptoms
Multiple lines of evidence suggest that pathological processes of AD begin years before the onset of clinical symptoms (Holtzman, Morris, & Goate, 2011). Depending on the degree of cognitive impairment, the progression of AD occurs in three main stages, referred to as early or mild stage, middle or moderate stage, and late or severe stage (Tsekleves & Keady, 2021). In early-stage AD (also known as mild cognitive impairment), symptoms typically include forgetfulness, especially difficulty remembering recent events, language problems such as shrinking vocabulary and decreased verbal fluency, and subtle problems with the executive functions of organizing, planning, and attentiveness (Tsekleves & Keady, 2021).  

At this stage, patients can live independently for most of the time, but may need assistance with cognitively demanding activities (Förstl & Kurz, 1999). Dysfunctions in olfaction may begin at the prodromal stage of AD and worsen over time.  

During the middle stage, AD patients are more likely to experience many of the early-stage symptoms but with an increasing degree of severity. For instance, memory problems worsen, long-term memory becomes impaired, and the patient may fail to recognize close relatives. Speech difficulties become more evident, leading to paraphasia.    

Moreover, significant deterioration in logical reasoning, organizing, and planning is often noticed (Förstl & Kurz, 1999). At this stage, one-third of AD patients exhibit behavioural and neuropsychiatric symptoms, including anxiety, emotional liability, apathy, sleep disturbance,  hallucinations, and illusionary misidentifications (Förstl & Kurz, 1999; Tarawneh &  Holtzman, 2012).

In the late stage of AD, cognitive functions are severely impaired, and the patient becomes completely dependent upon caregivers. Language is reduced to simple phrases, ultimately leading to complete loss of speech. Alongside these manifestations, the patient experiences difficulty in performing daily life activities, such as walking, sitting, chewing, and swallowing. Extreme apathy and exhaustion can also be seen (Förstl & Kurz, 1999).  

Factors involve in Alzheimer’s disease
Neurochemical factors such as Acetylcholine, Somatisation, Substance P, Norepinephrine and environmental factors such as Cigarette smoking, Certain Infections, Metals, industrial or other toxins and Use of cholesterol lowering drugs (statin) involve in progression of Alzheimer.

Genetic and immunological factors such as oxidized LDL receptor 1 and Angiotensin 1-converting enzyme, are tied to the way the brain cells bind to Apolipoprotein4 (APOE4) and reduce build-up of harmful proteins, known as plaques, in the brain, respectively.  

Diagnostic tests

• Psychiatric assessments.  
• Mental status examination and neuro psychological assessment
  Laboratory tests.   
• Brain imaging (CT scan, MRI, PET, SPECT)
  
• CSF Examination  
• Electro-encephalogram (EEG)
• Electromyogram 

References

• Alexandrov, P. N., Pogue, A., Bhattacharjee, S., & Lukiw, W. J. (2011). Retinal amyloid peptides and complement factor H in transgenic models of Alzheimer’s disease. Neuroreport, 22(12), 623.
• Armstrong, R. A. (2019). Risk factors for Alzheimer’s disease. Folia Neuropathol, 57(2), 87- 105.
• Förstl, H., & Kurz, A. (1999). Clinical features of Alzheimer’s disease. European archives of Psychiatry and clinical neuroscience, 249(6), 288-290.  

By: Aniqa anwar