What is Alzheimer’s Disease?

Alzheimer’s disease is a chronic and progressive neurodegenerative (meaning a reduction of the brain’s physiology and functions due to dying brain cells) disease characterized by deterioration of mental (also called cognitive) function in humans. The disease predominantly affects older persons, and as large groups of the world’s population currently enter the later stages of life, the prevalence of the disease will increase alarmingly over the next decades.

Alzheimer's Disease memory loss and confusion.
Credit: Doc-Advice

It begins in subtle ways. Early signs include sporadic memory loss and subtle changes in behavior that are often more noticeable to close loved ones than to the affected person. The illness gradually progresses over a decade or more after the initial signs start making their appearance. In its later stages, the patient may be unable to speak or comprehend language, and require assistance with most aspects of personal care, which would either be administered by home caregivers or in nursing homes.

Surprisingly, the specific cause of Alzheimer’s disease remains unknown, and current research suggests that it may be a syndrome (a group of symptoms that consistently occur together) made up of many factors, rather than a single disease. The most compelling risk factors include age and a family history of the disease, in particular a first-degree relative with the disease. Other risk factors include stroke, head injury, education level (lower has a higher prevalence of the disease), number of siblings, non-suburban residence, mother’s age at birth, hypothyroidism, and complex genetic factors.

Alzheimer’s disease usually progresses in three phases. First, a prolonged initial phase occurs, during which time subtle signs are noticed but no clear diagnosis can be made. This first phase is followed by a second period during which time mild but clearly discernible symptoms can be detected. During this phase, patients increasingly suffer memory loss, a decreased ability to carry out everyday activities such as cooking, shopping, and taking care of their personal hygiene, and exhibit increasingly impaired judgment. The third phase is a moderate to severe, highly symptomatic period, during which time patients require around-the-clock supervision and show steadily increasing and severe impairments in basic areas of human function, including movement, speech, continence (urination and bowel movements), and eating and drinking.

What are the most trusted predictions for the future as it relates to the prevalence of Alzheimer’s disease? Several studies – including one by the U.S. General Accounting Office – predict the future prevalence of the disease using past numbers. In 2000, there were between 2 and 5 million individuals with Alzheimer’s Disease in the United States. Of those, between 45 and 60 percent had moderate or severe disease. Future predictions using these numbers with the best methodologies available suggest that between 8 and 13 million people in the United States will be suffering from the illness by the year 2050. That number predicts not only a 4-fold increase in number of Alzheimer’s disease sufferers over the next few decades, but also that the number of caregivers – and the costs associated with caring for these individuals – will rise to alarmingly high numbers.