Hello all,
This is again a very intresting article about cognitive impairment and Lyme.
Introduction:
The
patient is a college graduate with Lyme
encephalopathy (LE). While stopped at a traffic light, she described her
thought processes as having a “fog-like” sluggishness. When the light changes,
she knows the change from red to green has significance, but at that moment
cannot recall that green means go and red means stop.
This
is one of many examples of cognitive impairments associated with Lyme disease. Although some cognitive symptoms are indirectly
a result of other neurological or emotional impairments, others are a direct
result of dysfunction of the cerebral cortex where cognitive processing occurs.
Laboratory tests such as SPECT scans, MRI’s, PET
scans, and psychological testing have demonstrated physiological and anatomical
findings associated with dysfunction
of the cerebral cortex in patients with Lyme and
tick-borne diseases. The examination of human and animal
brains have further supported these findings.
The cognitive impairments from Lyme
disease are very different than we see in Alzheimer’s disease. Lyme disease is predominately a disease of the white
matter, while Alzheimer’s is predominately a disease of the gray matter. Memory
association occurs in the white matter, while memory is stored in the gray
matter. White matter dysfunction is a difficulty with slowness of recall, and
incorrect associations. In contrast, gray matter dysfunction is a loss of the
information which has previously been stored. For example, and Alzheimer’s
patient may not recall the word “pen”, while an LE patient may have a slowness
of recall or retrieval of a closely related word. Some of the symptoms I will
describe are also found in encephalopathies
associated with other illnesses, such as chronic fatigue syndrome, lupus
stroke, AIDS, or other diseases which affect the brain. Although no single sign
or symptom may be diagnostic of Lyme disease in a
mental status exam, we instead look for a cluster and a pattern of signs and
symptoms that are commonly associated with Lyme
disease.
Everyone with LE has their own unique profile of
symptoms. The assessment of these signs and symptoms is one facet of the total
clinical assessment of Lyme disease.
There are many
ways of categorizing cognitive functioning. Let’s begin with a simple model of
perception, encoding these perceptions into
memory, processing what we perceive, imagery, and finally
organizing and planning a response.
Simple mental functions such as flexing the index finger of the
right hand, correlates with a relatively simple brain circuitry.. More complex functions such as flying an airplane requires the action of a more integrated neural circuitry.
The difference between these two actions is like the difference between playing
middle C on a piano vs. a symphony playing an entire concert.
Attention
Span:
Many
Lyme disease patients have acquired attention
impairments which were not present before the onset of the disease. There may
be difficulty sustaining attention, increased distractibility when frustrated,
and a greater difficulty prioritizing which perceptions are deserving of a
higher allocation of attention.
If we compare attention span to the
lens of a camera, we need the flexibility to constantly shift the allocation of
attention dependency upon the current life situation. For example, we shift
back and forth between a wide angle and a zoom lens focus to increase or
decrease acuity of attention depending on the needs of the current situation. A
loss of this flexibility results in some combination of a loss of acuity (hypoacusis), and/or excessive acuity to the wrong
environmental perceptions (hyperacusis). Hyperacuity can be auditory (hearing), visual, tactile
(touch), and olfactory (smell).
Auditory hyperacusis
is the most common. Sounds seem louder and more annoying. Sometimes there is
selective auditory hyperacusis to specific types of
sounds. Visual hyperacusis may be in response to
bright lights or certain types of artificial lighting. Tactile hyperacusis may be in response to tight fitting or scratchy
clothing, vibrations, temperature and merely being touched may be painful. Some
patients prefer to wear loose fitting sweat suits and are frustrated that being
touched can be painful. Olfactory hyperacusis may
result in an excessive reactivity to certain smells, such as perfumes, soaps,
petroleum products, etc.
Memory
Memory is the storage and retrieval of
information for later use. There are several different
memory deficits associated with LE. Memory is broken down into several
functions – working memory, memory encoding, memory storage and memory
retrieval.
Working memory is a component of
executive functioning. An example of working memory is the ability to spell the
word “world” backwards. Sometimes there are impairments of working memory as it
pertains to a working spatial memory, i.e. forgetting where doors are located
or where a car is parked.
Encoding is the placement of a
memory into storage. We cannot retrieve a memory that was not encoded correctly into memory in the first place. One patient described being upset that
someone had eaten yogurt in her kitchen during the night. Her activity during
the night was not encoded into memory.
Short term (recent) memory is the
ability to remember information for relatively brief periods of time. In contrast,
long term memory is information from years in the past (or remote).
In LE, there is first a
loss of short term memory followed by a loss of long term memory very late in
the illness. Patients may have slowness of recall with different types of
explicit (or factual) information, such as words, numbers, names, faces or
geographical/spatial cues. Not as common, there may also be slowness of recall
if implicit information, such as tying shoes, or doing other procedural memory
tasks.
Errors in memory retrieval include
errors with letter and/or number sequences. This can include letter reversals,
reversing the sequence of letters in words, spelling errors, number reversals,
or word substitution errors (inserting the opposite, closely related or wrong
words in a sentence.
Processing
Processing is the creation of associations which allow us to interpret
complex information and to respond in an adaptive manner. Some LE patients say
they feel like they acquired dyslexia or other learning disabilities, which
were not present previously. Examples of processing functions that may be
impaired in the presence of LE include the following:
Reading comprehension: The ability to understand what is being read.
Auditory
comprehension: The
ability to understand spoken language.
Sound
localization: The
ability to localize the source of a sound.
Visual spatial
perception: Impairments
result in spatial perceptual distortions. One example is microscopia,
in which things seem smaller than they really are. One patient lost depth
perception, and had several accidents when the car in front of her stopped. A
problem associated with visual spatial processing is optic ataxia, in which
there is difficulty targeting movements through space. For example, there may
be a tendency to bump into doorways, difficulty driving and parking a car in
tight spaces, and targeting errors when placing and reaching for objects. One
patient with optic ataxia, was stopped by a policeman
while driving two miles to my office because he kept swerving across the center
line. Before Lyme disease he could consistently shoot
13 to 14 out of 15 free throws from the basketball foul line. Now he averages 3
of 15, and misses some shots be several feet.
Transposition of latrerality: The ability to rotate something 180 degrees in your mind. For example, the ability to copy, rather than mirror, the movements
of an aerobics instructor facing you.
Left-right
orientation: The
ability to immediately perceive the difference between left and right.
Although this is a part of congenital Gertsmann’s
syndrome or angular gyrus syndrome, acquired
left-right confusion is the result of an encephalopathic
process.
Calculation
ability: The ability to perform mathematical calculations without using
fingers or calculators. Many LE patients describe an increased error rate with
their checkbook.
Fluency of
speech: The
ability of speech to flow smoothly. This function is dependent upon adequate
speed of word retrieval.
Stuttering: The tendency to
stutter when speech is begun with certain sounds.
Slurred speech: A slurring of words,
which can give the appearance of intoxication.
Fluency of
written language: The
ability to express thoughts into writing.
Handwriting: The ability to write
words and sentences clearly.
Imagery
Imagery is a uniquely human trait. It is
the ability to create what never was within our minds. When functioning
properly, it is a component of human creativity, but when impaired, it can
result in psychosis. Imagery functions that can be affected by LE include:
Capacity for
visual imagery: The
ability to picture something, such as a map, in our head.
Intrusive images:
Images that suddenly appear which may be aggressive, horrific, sexual or
otherwise.
Hypnagogic hallucinations: The
continuation of a dream, even after being fully awake.
Vivid nightmares: A tendency towards nightmares of a vivid Technicolor
nature.
Illusions: Auditory, visual,
tactile and/or olfactory perceptions which are distorted or misperceived.
Hallucinations:
Hearing, seeing, feeling and/or smelling something that is not present. In LE,
sometimes this takes the form of hearing music or a radio station in the
background. Unlike schizophrenic hallucinations, these are accompanied by a
clear sensorium, and the patient is aware hallucinations
are present.
Depersonalization: A loss of a sense of physical existence.
Derealization: A loss of a sense that the environment is
real.
Organizing and Planning
Organizing and planning a response is the most complex mental function,
and is dependent upon all the functions already described. These functions,
along with attention span and working memory, are referred to as executive
functioning. Organizing and planning functions that can be
affected by LE include:
Concentration: The ability to focus
thought and maintain mental tracking while performing problem solving tasks.
“Brain
fog”: Described
by many LE patients. Although difficult to describe in objective,
scientific terms: it is best described as a slowness, weakness, and inaccuracy
of thought processes. Prioritizing, organizing, and implementing multiple tasks
with effective time management.
Simultasking: The ability to concentrate and be effective
while performing multiple simultaneous tasks.
Initiative: The ability to
initiate spontaneous thoughts, ideas and actions rather than being apathetic or
merely responding to environmental cues.
Abstract
reasoning: The
capacity for complex problem solving.
Obsessive
thoughts: May
interfere with productive thought.
Racing
thoughts: May interfere with productive
thought.
An assessment of each of these areas of functioning is a
critical component in the clinical assessment of LE. The cognitive assessment
is only a part of the assessment of LE. Other components include the
psychiatric assessment, the neurological assessment,
a
review of somatic symptoms, epidemiological considerations and laboratory
testing when indicated. I have gradually developed a structured cognitive
assessment which focuses upon the areas mentioned after examining many patients
with late stage
neuropsychiatric Lyme
disease. I have also incorporated concepts from others that have made major
contributions in this area, such as Drs.
Rissenberg,
Nields, Fallon,
Freundlich and
Bleiwiss. It is difficult to explain exactly how
Lyme disease causes cognitive impairments. The variability
of these symptoms suggests an episodic
release of
a endotoxin or
cytokine which may contribute to the cognitive dysfunction. This is an area
where considerable research is needed, and is beyond the scope of this article.
The symptoms described are
often very difficult for patients to describe, and are difficult for many
physicians to understand. As a result, patients with these impairments are
sometimes erroneously viewed as being
hypochondriachal,
psychosomatic, depression, or malingering.
These symptoms are real and must be explained: that cannot be discounted as
being imaginary.
There are many treatment
strategies. Antibiotics and a number of different
psychotropics
are helpful to many. I have found
Aricept to be
helpful in the treatment of “brain fog” and problems with slowness of
retrieval.
To those of
you
who have LE, be realistic about your limitations and the validity of these
limitations. Use strong areas to compensate for areas of weakness. Avoid
excessive stress which compounds the problem. Be aware that certain tasks
challenge many higher level attributes. Maintain hope and retain an effective
working relationship with your family, support system and treatment team.
Lyme Girl x
**Always consult a LLMD (Lyme Literate Doctor) or your own health care professional.**
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