Cognitive Disorders 709
The early stage of dementia due to Lewy bodies is marked by visual hallucina-tions, fl uctuations in attention and consciousness throughout the day (with long pe-
riods of time spent staring into space or being drowsy), and a stiffness of movement
that is similar to that of people with Parkinson’s disease (rigid muscles, tremors,
slowed movements, and a shuffl ing style of walking). Clinicians may have diffi culty
distinguishing this form of dementia from Alzheimer’s, and about 20% of people
who were diagnosed with Alzheimer’s were found also to have abnormal Lewy bod-
ies (which were discovered on autopsy; Rabin et al., 2006). The main features that
are present in dementia due to Lewy bodies but tend not to be as marked in demen-
tia due to Alzheimer’s disease are:
(1) the presence of (visual) hallucinations early in the course of the disorder,(2) a tendency to retain the ability to name objects,(3) very poor visuospatial ability, and(4) impaired executive functions (Kaufer, 2002; Knopman, Boeve, & Petersen,
2003; Walker & Stevens, 2002).Like patients with Alzheimer’s disease, patients with dementia due to Lewy bodies
progressively deteriorate until death, which on average occurs about 8–10 years
after diagnosis.
Dementia Due to HIV Disease
The human immunodefi ciency virus (HIV) can cause widespread destruction of
white matter and of subcortical brain areas; this damage gives rise to dementia. The
symptoms of this form of dementia include impaired memory, concentration, and
problem solving, as well as cognitive slowing. Moreover, patients may exhibit signs
of apathy and social withdrawal or delirium, delusions, or hallucinations. They may
develop tremors or repetitive movements or have balance problems (McArthur et al.,
2003; Price, 2003; Shor-Posner et al., 2000). Antiretroviral medications that treat
HIV infection slow and in some cases may actually reverse the brain damage,
improving cognitive functioning (Sacktor et al., 2006).
Dementia Due to Huntington’s Disease
Huntington’s disease is a progressive disease that kills neurons and affects cogni-
tion, emotion, and motor functions; it leads to dementia and eventually results in
death. Early symptoms of Huntington’s include bipolar-like mood swings between
mania and depression, irritability, and psychotic symptoms (e.g., hallucinations or
delusions). Motor symptoms include slow or restless movements, and the symptoms
of dementia include memory problems (which become severe as the disease pro-
gresses), executive dysfunction, and poor judgment.
Between 5 and 7 people per 100,000 develop Huntington’s disease (Folstein,1989). Men and women are equally affected; the disease is usually diagnosed
when patients are in their late 30s or early 40s, but the age of onset can range from
4 years old to 85 years old.
Huntington’s disease is inherited and is based on a single gene. If a parent hasHuntington’s disease, his or her children each have a 50% chance of developing it.
Genetic testing can assess whether the gene is present. However, even if the gene is
present, the disorder does not always develop.
Dementia Due to Head Trauma
Just as head trauma can cause amnestic disorder, it can also cause dementia. The
precise defi cits and their severity depend on which brain areas are affected and to
what degree. The individual with this form of dementia may also exhibit behav-
ioral disturbances, such as agitation or anxiety. Such a patient may have amnesia for
events during and after the trauma, as well as other persistent memory problems.
In addition, he or she may exhibit sensory or motor problems and even personal-
ity changes (becoming increasingly aggressive or apathetic or suffering severe mood
swings) (American Psychiatric Association, 2000).
Huntington’s disease
A progressive disease that kills neurons
and affects cognition, emotion, and motor
functions; it leads to dementia and eventually
results in death.