Definitions of Memory Impairment

One of the most frequent questions I am asked is, “What is the difference between dementia and Alzheimer’s Disease (AD)?” It is a great question. But the frequency of the question from the public is an indication that we in the medical field have not explained the distinction well. I will use this article to explain the differences between normal age-associated memory changes, mild cognitive impairment (MCI), dementia, and yes, the distinction between dementia and AD.

Our brains, while capable of growth, learning, and development at any age because of neural plasticity, also change with age. For example, we process information slower than when we were younger, we struggle at times with finding a word (dysnomia), and we are challenged with retrieval and recall of information. Take comfort in knowing that a change may not be a symptom and does not mean disease! It is often a normal part of aging.

Age Associated Memory Change is a term used to describe those times when we misplace something, have difficulty recalling a name, or forget a scheduled event. We remember our forgetfulness and we tend to get frustrated with it. Remembering your forgetfulness is a good thing. These cognitive hiccups are a normal part of the aging process and do not impede or negatively affect our daily functions. I suggest you give yourself some grace and use humor to cope. You can also write things down and rehearse names, etc., to assist your recall.

Mild Cognitive Impairment (MCI) is a clinical diagnosis to describe deficits in cognition to include memory, language, problem-solving, or spatial skill that does not interfere with daily functioning. The deficit (s) represents a measurable decline for the person. However, the fact the deficit (s) does not interfere with daily functioning is critical as it means one is not suffering dementia. Approximately 30%-40% of those who suffer MCI-amnestic type (memory difficulty) are at risk for AD and need to be followed clinically and consider early proactive interventions that include lifestyle changes.

Dementia is a clinical diagnostic term that mandates a decline in general intelligence, forgetfulness, problems in other cognitive functions such as language, spatial skill, or problem solving, and personality change that impairs functional ability. It is the latter criteria, impairment of daily functions (driving, dressing, financial management, medication compliance, etc.) that renders the diagnosis of dementia.

Some Basic Facts on Dementia:

Dementia occurs primarily in later life though it can begin in middle age in rare cases. Research indicates 10%-15% of the nearly 60 million persons over age 65 suffer dementia, with risk for dementia increasing with age. Collier County ranks near the top of all counties in Florida for cases of dementia for those over 65 (12.4%). Almost all cases of dementia (95% to 97%) are irreversible. Examples of the few (3%) cases of reversible dementia include B-12 deficiency, thyroid disorder, dementia syndrome of depression, and even excessive alcohol intake if drinking is stopped prior to permanent brain damage. This is why it is important to follow your doctor’s recommendation to get your blood checked for thyroid and vitamin levels, as those deficiencies can be reversed and cognition returned to normal. The same is true for monitoring your mental health and lifestyle, as both can negatively affect cognition.

Once a diagnosis of dementia is established via a physical examination, clinical interview, blood labs, possible brain imaging, and neuropsychological testing, the next step is to determine the cause of dementia. There are over 70 different causes of dementia and Alzheimer’s Disease (AD) is the leading cause, accounting for 70% of all dementias. It also affects women more than men though we do not know why. As such, dementia is a clinical term used to describe a set of symptoms and signs while AD is one cause (leading cause) of dementia.

There exist newer sensitive blood tests and scans to determine the presence of plaque buildup in the brain that is a hallmark sign of AD and similar screens for genetic burden for AD (APOE-4) that assist in diagnostic clarification. It is important to note, however, that the diagnosis of dementia, including AD, must include cognitive and behavioral change and decline.

Other causes of dementia include vascular dementia (VaD) in which multiple strokes and disruption in blood flow to the brain leads to the changes associated with dementia; Lewy Body Dementia which looks like a combination of AD and Parkinson type symptoms; frontal-temporal dementia (FTD) that includes Pick’s disease and includes personality change as a hallmark first sign before memory or other cognitive changes.

Unfortunately, the public has confusion, concern, and even worry regarding cognitive health and possible onset of dementia. Indeed, surveys of adults and older adults reveal it is a leading fear regarding health. The worry one may have dementia is only fueled with benign moments of forgetfulness and most do not know what to do or where to go for help. Anxiety itself is a major cause of forgetfulness and can be treated. It is always a good idea to talk to your primary care physician (PCP) about your cognitive health at every visit. I am a big advocate for annual cognitive or neuropsychological exams starting at age 50 to generate your baseline and to measure empirically your cognitive health relative to your baseline. If measurable decline from baseline occurs, we can work to determine why such a decline has occurred and make important early interventions to correct what is causing the decline or to help slow any progressive decline.

MDR-Your Brain Health Matters has a Memory Assessment Center on Marco Island, 239-388-4134 (option #2) or drnuss@me.com for more information or to schedule a neuropsychological examination. There are other clinics in our region where cognitive evaluations can be coordinated with your PCP.

MDR Your Brain Health Matters is hosting a free memory screen on March 21, 2026, at the United Church of Marco Island, Disseler Hall, from 8:30 AM to 4:00 PM. To schedule your memory screen, please visit https://www.zeffy.com/en-US/ticketing/brain-health-screening. You can also access the link using the QR code.