A.  Overview                                               

From time to time, we all forget where we left our keys, walked into a room not knowing why we went there in the first place, or have trouble recalling what we ate last night.  If we are elderly, our first thought or fear is “Am I getting Alzheimer’s?”  Not necessarily. There are 100 conditions which mimic dementia (memory and thinking problems) that are actually reversible and treatable.   These are sometimes called “pseudodementia” “pseudo” meaning “not genuine or false”.  In other words, disorders or conditions that mimic dementia like symptoms.  For example, reactions to medications (geriatric patients are major consumers of prescription and over-the-counter drugs, and studies have revealed that a host of these medications produce effects symptomatic of cognitive decline), emotional distress (i.e., depression), vision and hearing (undetected problems of vision or hearing may result in inappropriate responses, which may be misinterpreted as dementia), nutritional  deficiency (i.e., folate, niacin, thiamine, vitamin B-12), endocrine abnormalities (hypothyrodism can cause confusion that mimics dementia), infections (older people can develop infections that produce a sudden onset of confusion), subdural hematoma (blood clot on the surface of the brain), normal pressure hydrocephalus (increased pressure in the brain due to interruption of the flow of the spinal fluid), brain tumors (tumors in the brain can cause mental deterioration),  or stroke (build up plaques can be surgically removed or medially treated to prevent stroke).  The reason an elderly person’s memory is not as sharp as when he/she was younger could also be subsequent to normal aging process of the brain.  As the body ages, so does the brain. As the body ages, it becomes physically more difficult to perform so does the brain; it becomes slower and loses its ability to think efficiently.       

The proportion of US citizens older than 65 years of age is growing steadily.  It is estimated that 20% of the population will be over 65 years of age by 2030.  This aging of the population is expected to bring an increase in the incidence of depression and dementia.  It has been estimated that as many as 10-20% of people over the age of 65 may be affected by chronic brain syndromes with a rise of 25% when individuals over the age of 80 yeas old are considered separately. As many as 4 million people have an intellectual impairment severe enough to meet the criteria for dementia.”  Although depression and dementia have many similarities, they also have important distinctions.    

The objective of this article is to elucidate the relationship between a most debilitating disease (Dementia of Alzheimer’s Type), depression, and normal memory decline due to aging (the brain starts shrinking after the age of 30 resulting in changes in thinking and behavior). Memory decline is one of the areas more sensitive to the aging processes and more prevalent in people over the age of 65.  

B.  How to Differentiate Between Dementia and Depression? 

It is important to know that “dementia” is a syndrome consisting of disturbances in distinct cognitive functions.  The main symptom in dementia is memory loss, but other functions are also affected, such as orientation, reasoning, problem solving, judgment, visual-spatial performance, language, and change in personality and emotions. Dementia is an acquired disorder with evidence of decline in cognitive functions from a previous level of function, as demonstrated by history and cognitive testing. As a result, social, occupational, and functional abilities can deteriorate. The most common pseudodementia and the most easily misdiagnosed is that associated with depression. General internists and family practitioners fail to recognize major depression in up to 20% of their outpatients with the disorder, either as depression misdiagnosed as dementia or vice versa.  The ability of primary-care physicians to recognize and correctly treat depression is important since only approximately 20% of people with depression are treated by mental health professionals.  This is especially crucial since both disorders especially depression, are treatable and misdiagnosis may cause an individual with potential full cognitive function to be unnecessarily confined in long-term care faculties (Yesavage, 1993).  While cognitive and behavioral difficulties (e.g., forgetfulness, sad mood, slowed thinking) in depression are similar to those with suspected dementia, performance on neuropsychological tests offers a distinct profile.  To diagnose dementia, a complete medical and neuropsychological evaluation is recommended and a complete patient history is very important. It is of vital importance that the physician understands the differences between depression and dementia.            

C.  What is Alzheimer’s disease?

 Alzheimer’s disease is a degenerative and progressive brain disorder characterized by memory loss and problems with language, planning and organization, reasoning and judgment, spatial abilities, and changes in personality and behavior.  It occurs most often in individuals over the age of 65 years.  A person’s chance of developing the disease increases with age.  Individuals 85 years of age and older have the highest rates of the disease.  While there are several types of dementia, Dementia of Alzheimer’s Type (DAT) is the most common form seen in the elderly and may be the single greatest source of dysfunction in people older than 85 years.  Researchers have estimated that approximately 360,000 new cases of DAT will occur each year.  More than 4 million Americans have DAT, and this number is expected to triple over the next 20 years with increasing life expectancies and the aging of the “baby boomers” generation.  Women are more likely than men to develop DAT, partly due to their longer life expectancy. Although there is no cure for DAT, effective medical and behavioral treatments are available.  These treatments may help to slow the progression of the disease.  Early diagnosis is important for managing the effects of the disease.  The average time between the diagnosis of DAY and death is 8-10 years, but this can vary from person to person. Therefore, legal and financial arrangements should be made regarding the individual’s estate and ongoing care.     

D.   What Happens to the Brain When It Ages? 

With advancing age every organ of the body undergoes alterations in one way or another. The brain is no exception.  Effects of aging on the brain are well documented.  The brain’s volume is at its peak until the age of 30 and declines gradually over the next decades.  Some structures are affected more than others.  Cortical atrophy (shrinkage associated with decrease in number and size of nerve cells) first shows up in the 40s, followed by dilation of ventricular size in 40s for men, bur not until 50s in women.  Studies have shown modest age related changes particularly in areas responsible for storage and retrieval of memory (i.e., temporal lobe, hippocampus, and basilar-subcortical regions). For every decade after 40s, the hippocampus loses 5% of its cells. This is very important as the ability to learn new information, retain and recall at a later time is processed by the cells in the hippocampus.  Other brain changes seen in non-demented “normal” elderly persons include the presence of senile plaques and neurofibrilary tangles, abnormalities associated with Alzheimer’s disease.  However, there is a distinction between normal aging and Alzheimer’s disease based on the distribution and extent of those features. Major cognitive changes with  aging has shown to be in the areas of nonverbal learning and memory, retention of verbal material, reaction time, visuospatial processing speed, and concentration.  However, these cognitive changes do not necessarily have to mean impairment affecting daily living or quality of life.   Even healthy elderly people show age-related decline in some cognitive functions.  Research has shown the regular aerobic exercise may slow the rate of cognitive decline and even reverse it.  Increase blood flow during exercise provides for better oxygenation of the brain.  Even playing video games may be good mental exercise for older person as it can speed up reaction time.  Evidently, exercise and healthy lifestyle are not only good for general physical health, but also helps the brain work efficiently.

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