According to scientists, these protein build ups block the ability of nerve cells to communicate with each other making it impossible for them to survive. Amongst these protein deposits, plaques are the deposits of beta-amyloid protein in the spaces between two nerve cells, while tangles are the deposits of tau proteins inside the nerve cells. These deposits are commonplace in humans, but their percentage is greater amongst the people suffering with Alzheimer’s disease. Another fact about these protein deposits is that they cannot be measured in a living person. The aforesaid studies are conducted during autopsies. 

As we all are aware, aging is the foremost cause or risk factor that may cause Alzheimer’s disease. According to a research conducted by the Canadian Medical Association Journal one out of every 100 people over the age of 65 years is suffering from Alzheimer’s. This number falls down to 1 in 14 over the age of 74 years and 1 in 4 over the age of 85 years. It is also observed that the probability of this disease doubles every five years, once a person crosses the age of 65 years. But as mentioned earlier, Alzheimer’s is not just the disease of the elderly. Around 5% of people get diagnosed with Alzheimer’s when they are in their 40s and 50s. 

As with many other diseases, heredity or family history is one of the top causes of Alzheimer’s disease. If a person has one parent or sibling suffering from Alzheimer’s disease, he/she is likely to suffer from the same. This probability is two to three times higher than a person with no family history of the disease. It also means that if more than one close family member has suffered from the disease, the likelihood increases even more. However, it is also to be understood that only around 7% of Alzheimer’s cases are associated with genetics. 

Apart from the causes mentioned above, researchers have also suggested a few more reasons that can be considered as the risk factors for Alzheimer’s. Recently, a few studies have identified a link between various injuries to the head and whiplash and Alzheimer’s. According to these studies, people who have had some serious accidents causing mild to severe, internal as well as external injuries to the head and neck region, might have damaged nerve cells in that particular part of the body. It means, if a person has met with an accident causing injuries to the head or neck tissues, he/she might serve to be at the risk of Alzheimer’s disease. However, not all the cases of head injuries and whiplash lead to Alzheimer’s, which is an important thing to keep in mind. 

Most cases of mild cognitive impairment have pertaining issues about memory from an early age. These people have limited memory as compared to other healthy person of the same age. Since they already have issues concerning memory and cognition, their problems are likely to increase along with the growing age. That is the reason why such people are rated at a great risk from Alzheimer’s than other people. Having said that, there are quite a few scientists who oppose to this hypothesis. A study performed in UK in the same context has rather surprising conclusions that are totally opposite to the aforesaid statement. According to its reports, people with mild cognitive impairment are at lesser risk of developing Alzheimer’s. Hence, the impaired memory during early age leading to Alzheimer’s could be just another speculation. 

One of the well known psychological disorders, Down’s syndrome is often associated with the development of Alzheimer’s disease. People suffering from Down’s syndrome are also considered to be at high risk of developing Alzheimer’s disease in their older age. Patients of Down’s syndrome have an extra copy of DNA, known as chromosome 21. Chromosome 21 contains the same types of proteins (beta-amyloid and tau) which are found in the brains of the people suffering from Alzheimer’s disease. As we know, deposits of these proteins block the chain of communication between nerve cells and eventually stop them from working altogether. Hence, patients of Down’s syndrome are considered to be at the risk of developing Alzheimer’s. 

People with several conditions like hypertension (high blood pressure), various other cardiovascular diseases and high cholesterol are at risk of developing Alzheimer’s disease. If these health conditions are developed due to poor lifestyle, then they are called as lifestyle factors that lead to Alzheimer’s. In other words, if the reason behind the cardiovascular disease of a person is not related to his/her lifestyle, then it has less chances of leading to Alzheimer’s. It is the reason why promotion of healthy and happy lifestyle, healthy diet and proper social interaction are some of the preventive measures for Alzheimer’s. Another heart condition, atrial fibrillation is also one of the causes for Alzheimer’s. A research done on around 37,000 patients suggests a strong connection between atrial fibrillation, arrhythmia and Alzheimer’s.

The plaques and tangles in nerve cells contain aluminum. Some researchers also suggest that aluminum from various food products and kitchen utensils gets absorbed into the body and hence deposited between the nerve cells. However, there is no firm evidence for these views, hence these are mere assumptions. On the other hand, a study carried out at the Rhode Island Hospital proved that there is a significant connection between high nitrate levels in foods and environment and Alzheimer’s and other such diseases like diabetes and Parkinson’s disease. According to this study, human is exposed to nitrates, nitrosamines and nitrites through processed foods and fertilizers. 

Apart from all the aforementioned causes, there are a few other risk factors and health conditions that are considered while discussing top causes of Alzheimer’s disease. These causes include, poorly managed type 2 diabetes, obesity, mini strokes or strokes, several chronic inflammatory conditions, history of clinical depression, etc. According to a few scientists, women are at higher risk of developing Alzheimer’s than men. Some scientists also claim that people with poor academic background are at higher risk of developing Alzheimer’s than highly qualified individuals but this required further study.