In 1901, Karl Deter, a railway worker, admitted his fifty-one-year old wife, Auguste, to a psychiatric institution with symptoms of memory loss, confusion, violent outbursts, and inability to use language. According to Karl, Auguste’s symptoms began to emerge in the late 1890s and were quite uncommon for the person he had come to know. She had become increasingly fearful and anxious and would sometimes scream loudly for several hours. Her condition became so overwhelming and debilitating that her family could no longer manage her care. For the next five years until she passed away, Auguste remained at the institution and was observed by a German psychiatrist, Alois Alzheimer. After her death, Alzheimer performed histological studies on Auguste Deter’s brain tissue. In the process, he discovered two abnormalities: Large abnormal clumps had formed between neurons, and ropelike tangles had formed inside neurons. Calling these abnormalities “a peculiar disease of the cortex,” Alzheimer presented his findings at a 1906 psychiatric conference in Germany, marking the first documented case of what is now known as Alzheimer’s disease. Over the next five years, eleven similar cases were reported in medical journals. Today, more than one hundred years later, there are approximately 35.6 million people suffering from Alzheimer’s disease worldwide. To the shock of many, the 2010 World Alzheimer Report projected that this number will almost double to 65.7 million cases by 2030 and will more than triple to 115.4 million cases by 2050.

Alzheimer’s disease is categorized as an incurable, degenerative neurological disorder. In popular language, Alzheimer’s disease is commonly used interchangeably with the term dementia, but they are not the same. Dementia is the general term used to describe a decline in cognitive abilities (memory, thinking, language, judgment, and behavior) and can be associated with a number of different neurological or psychiatric diseases. An important distinction, Alzheimer’s disease is the most common cause of dementia, accounting for 60% to 80% of all dementia diagnoses. It is primarily characterized by a loss of short-term memory as well as impairments in other cognitive functions such as language, problem solving, attention, and orientation. As the disease progresses, severe mood swings and unprovoked aggression are common. Eventually, the patient loses almost all language ability and motor function.

For the most definitive diagnosis, scientists use postmortem analysis of brain tissue. The tissue abnormalities first defined by Alzheimer as clumps and tangles among neurons in the cortex are more specifically defined as amyloid plaques and neurofibrillary tangles. Plaques are deposits of a protein called beta-amyloid, which scientists believe is one of the earliest signs of the disease process. Over time, the buildup of this protein in the brains of Alzheimer’s patients eventually disrupts effective communication between neurons. Scientists hypothesize that these amyloid accumulations can themselves trigger the formation of neurofibrillary tangles, which are made of a different protein called p-tau and have a distinct stringlike appearance. Like plaques, these tangles also interfere with neurons, but they do so by accumulating inside of them in large amounts and eventually killing them. The relationship between these tissue pathologies and behavioral symptoms is not always tightly correlated, however; plaques and tangles may appear in the brain well before symptoms of dementia appear. (Rather than by post-mortem analysis, these brain tissue pathologies are typically detected by magnetic resonance imaging, also called MRI.) Regardless, the consensus among diagnosticians is that Alzheimer’s patients who show progressive deterioration of brain function always show the plaque and tangle tissue pathology.

Although Alzheimer’s disease is commonly diagnosed in people over the age of sixty-five, early-onset cases — appearing at ages thirty to sixty and accounting for only 1% of total cases — represent a rare subset in which great advances have been made. This form of the disease can run in families. Studies of these families have identified several genes that, when altered, can cause Alzheimer’s disease. These genes implicate beta-amyloid as a central player in the disease and formation of plaques in the brain as an early manifestation of a disease process in the brain. Recent studies imaging the brains of older adults with and without dementia suggest that these plaques may first appear as early as ten years before the onset of clinical symptoms. The growth of this category may be concurrent with a growing recognition of the disease among diagnosticians, but it nevertheless causes great concern and contributes to the expanding effect of the disease.

The cost of care for those with Alzheimer’s disease can leave supporting families emotionally and financially debilitated. Currently, there are no cures for this disease, but there are two types of drugs available that slow disease progression. Unfortunately, both types provide only marginal improvements in cognitive symptoms. Making matters worse, these drugs tend to work for only about half the patients who take them, and among those patients, the effects are moderate and temporary. Based on the discovery that beta-amyloid plaques appear early on in the disease, even before symptoms appear, many drug companies are trying to inhibit the production of this protein or target its removal as a possible strategy to treat the disease. More than one hundred years after the first documented case of Alzheimer’s disease, staggeringly little is known about how to effectively ameliorate or cure it.

The large cost of care associated with Alzheimer’s disease — the equivalent of approximately $604 billion in 2010 — is a rapidly growing global concern. In comparison of scale, if Alzheimer’s disease were a country, it would be eighteenth on the list of all world economies. In the United States alone, the cost of Alzheimer’s treatment ran upward of $172 billion in 2010. These numbers are overwhelming, especially considering that life expectancy is on the rise and increasingly more people are likely to develop Alzheimer’s disease. Recently, the World Health Organization estimated that there will be more than 1 billion people over the age of sixty by 2020. The growing number of potential sufferers and the inevitable increase in care demands will have an enormous economic effect on health care and social services. With these staggering costs, governments will need swift action to eradicate this disease.

With the number of cases on the rise, Alzheimer’s is a disease that will affect every single one of us in our lifetime, if not directly, then via a relative or friend. It is therefore critical to have a full understanding of this condition and the issues surrounding treatment and cost of care. In this Spotlight, we provide resources to help you understand the basic facts about Alzheimer’s, its familial and economic effects, and new research on diagnosis and treatment.

— Svetlana Rosis, Ph.D.

Image: Alfred Pasieka/Science Source.