It is estimated
that adults who survive to the age of 80 have a 30% risk
of developing severe Alzheimer’s
Disease or Related Disorders (ADRD) (Gurland and Cross,
1986). Aside from Alzheimer’s, related disorders
include other dementias such as "multiple-infarct,
normotensive hydrocephalus, Pick’s Disease, Guam-complex,
alcoholic, pugilistic, and those associated with Parkinsonism,
Huntington’s, Chorea, and Down Syndrome" (Gurland
and Cross, 1986, p. 12). Unfortunately, misdiagnosis of
ADRD by both specialists and generalists occurs more often
than commonly suspected. It is estimated that in medical
practice, the frequency of misdiagnosis can range from
under 10% to over 50% of cases (Gurland and Toner, 1983).
Importance of the Diagnoses of Memory
Disorders
Often, signs of dementia, especially early dementia, are
casually attributed to senility or aging. However, although
senility may occur frequently in the elderly population,
it should not be easily dismissed. For example, the high
prevalence of cardiac disease in the aging population has
served as an impetus for improved diagnosis, treatment,
prevention, and ongoing research. Without proper diagnosis,
the prevalence of memory disorders and dementia is often
underestimated. This underestimation may undermine the
importance of increased research efforts and appropriate
healthcare support systems.
Diagnostic matters are complicated further by the need
to exclude for factors such as depression and benign senescent
forgetting. Accurate identification of memory disorders
and dementia is best conducted through comprehensive assessments
which involve the following: 1) a thorough clinical history,
2) neurological and physical exam, 3) routine laboratory
testing, 4) CT/MRI, and 5) neuropsychological testing (Gurland
and Cross, 1986). Aside from diagnosis, neuropsychological
testing can assist in evaluating the patient's ability
to 1) function independently, 2) drive a motor vehicle,
3) perform competitively at an occupation, as well as serving
to 4) address legal issues of competence, and 5) provide
a baseline from which to follow the course of a disorder
or determine the effectiveness of an intervention.
A common diagnostic dilemma is the differentiation of
actual brain-related dementia from "pseudo-dementia." Pseudo-dementia
is the term used when a patient presents with complaints
of cognitive dysfunction but has no identifiable neuropathological
disorder. While the term is often used for cognitive dysfunction
secondary to depression, it has become recognized that
pseudo-dementia may also occur in a variety of psychiatric
conditions and is not necessarily limited to the elderly.
The differentiation is especially critical as very different
treatments and outcomes are associated with each condition.
While it has been commonly thought that depression itself
causes cognitive impairment, impairment is neither severe
nor global (Grady and Seebauer, 1993). Findings of deficits
in the clinically depressed appear to involve primarily
aspects of psychomotor speed and motivation and attention. "Effortful
processing," the ability to actively organize, rehearse
and retrieve new material from memory (Hasher and Zacks,
1979), may be affected by the mood disorder, although recognition
and general knowledge may be intact. Apparent deficits
in learning and memory in the pseudo-dementia patient may
actually be due to reversible conditions such as depression
rather than to actual failure of encoding and storage.
Neuropsychological testing is a useful and important component
of a comprehensive assessment for dementia. Simply testing
memory functioning is not sufficient. In order to identify
underlying patterns of cognitive dysfunction, assessment
must also encompass attention and concentration, intellectual
functioning, reasoning and problem-solving, and output
and expression. The patient's emotional status must be
assessed carefully as well. With this information, the
neuropsychologist can determine whether the cognitive symptoms
the patient complains of are actually present and whether
the pattern is consistent with a dementing disorder or
some other problem. In conjunction with the physician,
a complete picture of the patient’s physical, cognitive
and emotional status can be developed and appropriate treatment
may be instituted.
Memory as a Construct
Memory is an exceptionally problematic construct to define
in that it is multidimensional. Furthermore, a variety
of theoretical models are employed to describe it. A heuristically
basic way of understanding memory is by viewing it as a
sequence of stages. Initially, the individual perceives
stimuli through sensory channels whether visual, auditory,
tactile, olfactory, or gustatory. At this initial stage,
skills of attention and concentration are required for
immediate registration. Sensory input then proceeds to
a second stage of immediate short-term storage or sensory
storage. It is from this latter stage that immediate short-term
recall can occur, such as the repetition of a series of
digits. It is known that the normal adult can store approximately
seven bits of data upon demand, such as seven letters or
numbers. Chunking, or grouping of bits of data, can help
to extend one’s ability to hold information in short-term
storage. Thus, one is able to recall a ten digit phone
number from memory by chunking the area code and exchange.
For longer-term storage to occur, information is transferred
to a third stage of working memory. Here, the input is
either recognized as related to previously stored information
patterns and related to a context, or it is processed,
examined, and reanalyzed to form a new pattern to be stored.
Once processed, the information is transferred to the fourth
stage of long-term memory.
Although input may make its way into long-term storage,
memory also requires efficient retrieval of information,
the next stage in the memory process. Deficiencies in retrieval
are often seen in tip of the tongue and word-finding difficulties.
Finally, although information may be retrieved, it must
be effectively expressed whether through verbalization
or action. Such problems in expression are often seen in
aphasic patients and can interfere with the direct assessment
of a memory disorder.
When assessing a memory disorder, one must consider the
stage or stages at which difficulties are occurring. Similarly,
one must consider whether a language disorder is interfering
with the direct assessment of memory.
A patient may be able to attend, store, and retrieve but
may experience difficulties in the expression of output.
One must also consider whether there are deficits in a
particular mode of memory input. For example, some individuals
may exhibit intact visual or motor memory with impaired
memory for language-based stimuli.
Different types of memory have been posited
and studied. For example, episodic memory refers to the
ability to retrieve stored information about experienced
life events, whereas semantic memory refers to the ability
to retrieve information encoded through language. Such
differences are represented by the memory of a walk on
a beach versus recall of the year Christopher Columbus
discovered America. In the early stages of dementia, episodic
memory may present as stronger than semantic memory.
Implications of Memory Disorders
Similar to episodic memory, memory for familiar information
stored in long- term storage may appear stronger than that
for newly learned or stored information. Thus, cognitively
impaired patients are often confused when they travel or
change residences. During hospitalizations, these individuals
appear to be even more demented and unmanageable.
The denial of memory and cognitive difficulties
in early dementia is often associated with the fear of
the possibility of being placed in a new, unfamiliar environment
such as a nursing home. Memory is an integral factor in
the learning of new tasks and acquisition of new skills.
Patients who still exhibit some awareness and insight into
their deteriorating cognitive skills often panic at the
thought of failing at such basic tasks as locating the
new silverware drawer. Their fear of disorientation and
loss of control are often great but not clearly voiced
to their family members. It is easy for others to interpret
their denial, avoidance, and resistance to change as stubbornness
and negativism, rather than as their attempts at preserving
some sense of competency and self-esteem. Dementia (or
other brain disorders such as head injury or stroke) may
also involve a component of organic unawareness, in which
the individual is not capable of observing and judging
his or her own performance due to impairment in brain systems
which mediate these abilities. What may be interpreted
as denial for emotional reasons may, in fact, be lack of
awareness for cognitive reasons.
Treatment Options
Treatment options for memory disorders may include medication,
cognitive rehabilitation therapy, or environmental management.
Tacrine hydrochloride (Cognex) is a drug that presumably
acts by elevating acetylcholine concentrations in the cerebral
cortex. In patients in the early stages of AD, cholinergic
pathways from the basal forebrain to the cerebral cortex
and hippocampus (a brain structure highly involved in memory
processing) are thought to be selectively affected. By
increasing the available level of acetylcholine in those
regions, Cognex appears to improve cognitive functioning
in several domains. However, as the disease progresses,
the spread of affected cholinergic pathways renders the
medication less useful. Cognitive rehabilitation therapy
is especially helpful for disorders of memory resulting
from head injury or stroke and includes both direct practice
and training in compensatory strategies. Cognitive rehabilitation
is not typically helpful for the patient with dementia,
especially in the middle to later stages, as so many cognitive
and intellectual abilities are affected.
Family and caregiver counseling in strategies
of effective communication and environmental management
(arranging the household to maximize memory and minimize
confusion by the use of signs, notes, visual cues, etc.)
is more helpful for these individuals.
Conclusions
Memory is a seemingly elusive, complex process which lies
at the basis of all learning and adaptation. As the older
adult population swells, so to will the prevalence of memory
disorders and ADRD. As a nation, we will need to prepare
ourselves with resources and support systems for those
individuals whose afflictions will be primarily brain-related,
rather than physical, in nature. These individuals may
not require hospital beds or hospital care but may need
costly, ongoing supervision and redirection. Residential
facilities which can serve the cognitively impaired, as
opposed to the strictly physically impaired, will help
meet growing healthcare needs.
Community resources such as family support groups and
caregiver respite can ease the burden on families and friends.
Continued diagnosis, treatment, and management of memory
disorders in older adults will set the stage for changes
in public policy and in the healthcare environment, to
better serve our growing population of older adults.
Dr. Rosemarie Scolaro Moser is an MCMS
Alliance Past President and is in private practice located
at 3131 Princeton Pike, Lawrenceville, New Jersey. |
