Does Stress Impair Memory?

Contributed by: Dennis Fortier, President, Medical Care Corporation

The relationship between stress and memory is complex.

We all know that emotionally intense experiences tend to be effectively stored for retrieval over a lifetime.  This is an evolutionary mechanism that guides us away from dangerous situations we have previously encountered, and toward those where significant rewards were garnered.  Since stress is correlated with emotional intensity, it makes sense that there is a relationship betwen stress and memory.

In a more thorough look at the relationship, researchers from the University of Edinburgh recently published their findings in the Journal of Neuroscience.   According to their study, a moderate amount of stress can aid memory, but an intense or sustained amount of stress can be harmful.

They identified two distinct receptors in aging brains that react to cortisol, a hormone produced as a by-product of stress.  The first receptor reacted to low levels of cortisol and improved memory. The other, which reacted to higher levels of cortisol, had a negative impact on memory capacity. 

The most likely conclusion from this work is that a single stressful incindent is likely to be stored for later recall, but a lifestyle of sustained high stress, is likely to impair overall memory function.

3 Stages of Alzheimer's Disease

Contributed by: Dennis Fortier, President, Medical Care Corporation

Alzheimer's disease was clarified today.

With the announcement of new diagnostic guidelines, developed in tandem by the National Institute of Aging and the National Alzheimer's Association, we can now conceptualize the disease across a continuous spectrum with three contiguous stages of progression.  There is a pre-clinical stage, a mild cognitive impairment stage, and a dementia stage.

Pre-clinical Stage
The purpose of defining this very early stage, before the presence of any clinical symptoms, is purely to benefit research.  While there are no symptoms of disease in this stage, researchers have noted that certain biological changes, including protein levels in the brain, blood, and spinal fluid, seem to change in fairly predictable ways during the years before Alzheimer's patients manifest symptoms.  The changes are not sufficiently telling to diagnose the disease at this early stage, but identifying these individuals and enlisting them as research subjects is an important goal for the field.

Importantly, physicians will not use these criteria to diagnose such early stage Alzheimer's. The definition of this stage is purely to help researchers speak a common language about similarly characterized research subjects. 

Mild Cognitive Impairment Stage
In this stage, patients have clear underlying pathology consistent with Alzheimer's disease, and have also developed clinical symptoms of memory loss or other cognitive deficits.

The identification of this stage is the most important aspect of the new guidelines, as it will enable earlier intervention for patients who are, almost certainly, in the progressive throes of Alzheimer's, but still have relatively healthy brains.  It is hoped that existing treatments, and new treatments in the pipeline, will be optimally effective in these early stage patents.

Dementia Stage
This stage is quite consistent with our former view of the disease.  It requires the hallmark pathology of amyloid plaques in the brain, plus cognition so impaired as to meet the criteria for dementia (two or more realms of impaired cognition that interrupt daily activities of living). In the past, we did not call the problem "Alzheimer's disease" until the patient reached this end stage condition.

New Guidelines for Alzheimer's Disease are a Step in the Right Direction

Contributed by: Dennis Fortier, President, Medical Care Corporation

The announcement of new guidelines for diagnosing Alzheimer's disease is being widely covered in the press today.  The move is a solid step in the right direction, but is spawning some confusion about why the change is necessary, and how it might help.

Biggest Change: AD starts prior to Dementia
The most important change is that we will now recognize Alzheimer's disease in its early stages, prior to the patient suffering massive brain damage and becoming demented.  This is a more difficult diagnosis to make and, as such, requires a thoughtful approach.

I wrote more extensively about the benefits, and the ensuing confusion about new diagnostic guidelines for Alzheimer's disease, when the draft versions of these documents were first discussed in the summer of 2010.   I encourage you to click back and read those thoughts, but the short summary is below.

Perspective on Former Guidelines
According to the former guidelines, put in place nearly 30 years ago, Alzheimer's disease was defined in part by the presence of dementia.  As readers of this blog know, dementia requires impairment so severe that a person cannot independently care for themselves.  In this regard, the term "mild Alzheimer's" means "barely demented due to Alzheimer's pathology"'  This is a misnomer because, even in its "mild" stages, dementia is a severe condition.

To put that in perspective, imagine if we could note the high blood sugar and blurry vision caused by diabetes, but we couldn't diagnose and treat it until the patient's kidneys failed.  Any guideline, suggesting that symptoms must be severe before diagnosis, is in direct conflict with early intervention.

The former guidelines were problematic as illustrated by this example:  Suppose a 75 year old person, with a family history of Alzheimer's, noticed subtle signs of memory loss and visited a physician.  The physician then confirmed the declining memory and sought the cause of the problem.  After ruling out depression, sleep disorders, medications, thyroid malfunction, poorly controlled diabetes, vitamin deficiency, and stroke as possible causes, he noted on an MRI scan of the brain that the patient's hippocampus was shrinking.  This would be a strong indication of Alzheimer's disease.

However, since the patient in this example had only subtle memory loss, not severe cognitive impairment meeting the criteria for dementia, the physician could not diagnose Alzheimer's and initiate treatment.  According to the old guidelines, the physician would let the Alzheimer's pathology progress for months or years, until the patient suffered enough irreversible brain damage to become demented, and then they could diagnose Alzheimer's and initiate treatment.  That clearly makes no sense.

New Guidelines
Under the new guidelines, if a patient has memory loss or other cognitive deficits, and common causes of such deficits are ruled out, and pathology is consistent with Alzheimer's, then we should recognize the condition as early stage Alzheimer's disease and begin treating it.  This holds even if the patient's cognitive problem is subtle and does not meet the criteria for dementia.

Since earlier intervention bodes well for better treatment outcomes, this is a solid step in the right direction.