Lyme Disease and Cognitive Impairments

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Lyme Disease and Cognitive Impairments

by Robert Bransfield, M.D.

_http://www.mentalhealthandillness.com/lymeframes.html_

(http://www.mentalhealthandillness.com/lymeframes.html)

 

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 “penâ€, 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 fogâ€: 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.