It occurs in up to 50 percent of 85 year olds in the West. In India the rarity of Alzheimer’s disease has been linked to the consumption of high levels of turmeric and other spices.
The precise cause of AD is unknown but several factors are known to be associated with its development.

Turmeric , rosemary , ginger and garlic show impressive protective and curative effects against this disease. Therefore these and possibly other spices could be considered the best natural preventives and treatments for Alzheimer's disease.

Alzheimer’s disease is a debilitating and ultimately lethal neurodegenerative disorder that currently afflicts about 18 million people worldwide. The incidence of the disease increases exponentially with age and, with life expectancy increasing in many parts of the world, global prevalence is expected to double by 2025. Alzheimer’s disease is characterized by progressive intellectual deterioration, starting with memory loss that is followed by intellectual impairment, poor decision making, uncoordinated movements, speech impediments and loss of recognition of familiar people and places. The causes of Alzheimer's disease are poorly understood and effective preventative or therapeutic drugs have yet to be developed.  

In most Western nations, Alzheimer's disease is the commonest cause of dementia and one of the most devastating and prevalent diseases amongst the elderly. In these countries more than 2 percent of people over the age of 65 show signs of the disease while up to 50 percent of 80 year olds show symptoms of Alzheimer's disease. Although the incidence of Alzheimer's disease is increasing rapidly in many developing countries, on the Indian subcontinent it remains extremely rare, even among the high-risk age groups. Recent studies have associated this reduced risk primarily with the consumption of turmeric that, together with several other spices, has been shown to have protective and curative effects against the disease.

Causes of Alzheimer’s disease

     The causes of Alzheimer's disease are not fully understood, but there are several pathological processes that occur in those afflicted with the disease. The most prominent of these is the deposition of an abnormal protein, Beta-amyloid, in the brains of Alzheimer’s disease sufferers. Beta-amyloid is deposited in the form of plaques between the neurons and also accumulates in the walls of small blood vessels in the brain, where it impedes the flow of blood to brain tissues. The aggregation inside the neurones of abnormal amounts of tau protein filaments is another pathological feature of Alzheimer's disease. A further process associated with the disease is atrophy, or wasting, of nerve tissue which leads to the loss of synapses and their associated neurotransmitter chemicals from key areas of the brain. In all cases, the precise causes of these pathological processes are unclear but they and certain other factors appear to increase the risk and aggravate the development of Alzheimer's disease.

Some Factors Associated with Alzheimer’s Disease

• Toxins: Exposure to excessive amounts of potentially toxic metals like aluminum, copper and zinc has been associated with Alzheimer's disease.

• Chronic oxidative stress is being investigated as one of the pathological processes underlying the development of the disease. Most spices, in addition to turmeric, rosemary, ginger and garlic should be able to provide beneficial antioxidants for Alzheimer's disease

• Chronic systemic inflammation may also be a causative factor, as recent studies have found that individuals who take aspirin and other non-steroidal anti-inflammatory drugs have much lower incidences of Alzheimer's disease than those who do not take these drugs. 

• Genetics: There is evidence that genetic factors may play a minor role as a cause of Alzheimer's disease.

Spices and the Prevention of Alzheimer’s Disease

As pharmaceutical companies battle – as yet unsuccessfully – to find either preventive or curative drugs for Alzheimer’s disease, potent weapons against it already exist in the form of several common spices.
Confirming epidemiological pointers that diet plays a key role in Alzheimer's disease’s low incidence in India are several promising laboratory studies of the phytochemical curcumin. Found in large quantities in turmeric , curcumin has been shown to inhibit the deposition of amyloid in the brain and, in some cases, actually reverse this process. Studies have also shown that rosmarinic acid, present in rosemary and several other spices as well as gingerol and zingerone found in ginger (that also contains curcumin) have similar protective effects.

Although these are the most thoroughly researched spices in respect of Alzheimer's disease, evidence is accumulating that several others, including garlic, have similar preventive effects against this disorder. Moreover, it is almost certain that the list of spices shown to protect us against Alzheimer's disease will continue to grow. In particular, the preventive effect of long-term ingestion of aspirin suggests that the many salicylate-rich spices confer similar protection against this illness.

Research continues to reveal that, as in the case of other degenerative diseases, there are multiple underlying processes responsible for Alzheimer's disease, toxic metal accumulation, oxidative stress and chronic systemic inflammation being the prime suspects. Once again it seems obvious that to prevent the disease from occurring, we should take a "shotgun approach"; by using spices and other foods that provide an array of beneficial chemical compounds we will protect ourselves against the processes that are known to underlie this condition. In all likelihood the wide range of actions exhibited by the phytochemicals in spices also counteract other, yet undiscovered, processes or toxins associated with Alzheimer's disease. 

Alzheimer’s disease could affect any one of us and, as spices are the only known natural substances we can take to prevent the onset of this debilitating illness. In the context of Alzheimer's and other diseases spices are remarkable food-medicines we cannot afford to go without.