What is Alzheimer’s Disease

by Dr. Abhijit Hazra (MBBS, DNB) last updated -

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Alzheimer’s disease (AD) is the most common cause of dementia, accounting for 60-70% of cases. Dementia is characterized by a disturbance of multiple brain functions, including memory loss, thinking, orientation, comprehension, calculation, learning capacity, language, and judgment.

Alzheimer’s and Dementia

Other types of dementia include vascular dementia, dementia with Lewy bodies, and normal pressure hydrocephalus, etc. However, an overlap exists between them, thus diagnosis isn’t always straightforward and mixed forms are not uncommon. Alzheimer’s disease is characterized by a progressive decline in the cognitive function, memory, thinking, language, and learning capacity and it substantially increases among people aged 65 years or more.

AD should be differentiated from normal age-related decline in cognitive function, which is more gradual and associated with less disability. The disease often starts with mild symptoms and ends with severe brain damage. Furthermore, people with dementia lose their abilities at different rates.

A 2019 research paper published in the Sciences Advances revealed that a bacterium called Porphyromonas gingivalis (Pg) may be linked with Alzheimer’s pathology. This bacteria is commonly associated with chronic periodontitis. Researchers found that the Pg bacteria caused an increase in amyloid beta, part of the amyloid plaques associated with AD. 


How many people have Alzheimer’s worldwide?

As per the World Health Organisation, the total number of people with dementia in 2010 was estimated at 35.6 million worldwide and it is projected to nearly double every 20 years, to 65.7 million in 2030 and 115.4 million in 2050. The total number of new cases of dementia each year is nearly 7.7 million worldwide, implying that there is one new case every four seconds. 

Treating and caring for people with dementia currently costs the world more than US$ 604 billion per year. This includes the cost of providing health and social care as well as the reduction or loss of income of people with dementia and their caregivers. In 2008, the WHO declared dementia as a priority condition through the Mental Health Gap Action Programme in view of the impact of this disease.

Treatment and Strategies

There are no available treatments that stop or reverse the progression of the disease, which worsens as it progresses, and eventually leads to death.

There are currently no specific tests that can confirm with a 100% certainty the diagnosis.

A combination of brain imaging and clinical assessment checking for signs of memory impairment is used to identify patients.

It is thus mandatory to consult a neurologist or an expert medical practitioner if Alzheimer’s is suspected.

The cause is understood to be premature death of brain cells in specific locations in the brain which subserve the function of memory and learning and with time involves widespread areas of the brain.

Dietary and Lifestyle Changes

  • According to Richard Mayeux and Yaakov Stern, diet, physical activity, or other diseases potentially play a role in the onset of Alzheimer’s disease.
  • Diabetes, hypertension, smoking, obesity, and high blood cholesterol have all been found to increase risk.
  • A higher level of awareness about the disease as well as dietary changes like including the Mediterranean diet was shown to decrease the risk.
  • Foods high on anti-oxidants and having anti-inflammatory properties may thus have some benefit in terms of preventing Alzheimer’s.
  • A Mediterranean diet is high in foods such as fruits, vegetables, and lean protein, however, the exact mechanism is still unknown. Diet thus may play some role in prevention.


Currently approved treatments available cannot delay the progression of AD but can provide a transient improvement of mental function, thus prevention is the best option.

Avoiding smoking, foods high in fat and refined carbohydrates, controlling diabetes and blood pressure, managing weight, and following a diet high in fruits, vegetables, and lean protein is the best way to prevent Alzheimer’s as per the National Institute of Health (NIH).


To summarize, Alzheimer’s is a major health problem around the world. With no good treatment available, prevention is the best option.

Diet has a leading role in this regard along with the avoidance of smoking. It also influences the management of diabetes and hypertension thus indirectly helping to prevent Alzheimer’s.

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About the Author

Dr. Abhijit Kumar Hazra, MBBS, DNB, is a senior consultant neurosurgeon at Apollo Main Hospital, Chennai. He completed his fellowship in cerebrovascular surgery at the Tokyo Medical University in the year 2010. Dr. Hazra’s areas of interest include endoscopic skull base surgery, full endoscopic trans-foraminal interlaminar lumbar spine surgery, and cerebrovascular surgery.

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