704 CHAPTER 15
(Harvey, 2005b; see Chapter 12). Although some people develop schizophrenia
later in life (which can make it diffi cult to distinguish it from dementia by the
age of onset), such later-onset schizophrenia often progresses rapidly from the pro-
dromal phase—when symptoms are just beginning to emerge—to a full psychotic
episode, whereas psychotic symptoms are likely to emerge more gradually with
dementia (Harvey, 2005c).- Depression.A clinician may fi nd it particularly diffi cult to distinguish between
depression and dementia in elderly patients—both disorders can involve memory
problems, poor concentration, and other cognitive dysfunctions. The timing of
the onset of symptoms can help distinguish the two disorders: Patients with de-
pression often have relatively normal cognitive functioning before becoming
depressed and then rapidly decline. In contrast, those with dementia may have a
slower cognitive decline. - Delirium.With some patients, the particular symptoms can make it diffi cult for
mental health clinicians to determine whether delirium, dementia, or both are
present (see Table 15.9). Friends or family members may be called on to provide a
more accurate history of a patient’s symptoms than the patient can provide. - Amnestic disorder. Both amnestic disorder and dementia involve memory prob-
lems. However, a diagnosis of dementia requires that additional cognitive defi cits
be present. - Normal aging. It is normal for adults to experience some decline in cognitive func-
tioning with increasing age; to be considered as dementia, an elderly person’s cog-
nitive problems must be signifi cantly worse than would be normally expected and
must be caused by a medical condition or related to substance use.
Unique to Delirium Unique to Dementia Common to Both
Delirium and Dementia- Delirium has a rapid onset.
- Symptoms (including changes
in consciousness) fl uctuate
within a 24-hour period. - Hallucinations—frequently
visual—are present. - Symptoms often gradually
improve. - The person is not alert and
focused.- Dementia has a gradual onset.
- Symptoms typically do not
fl uctuate within a 24-hour
period. - Hallucinations are often
absent. - Symptoms rarely improve.
- The person is consistently
alert.- Memory problems
- Problems with other
types of cognitive
functioning
Table 15.9 • Symptoms Unique and Common to Delirium and Dementia
Understanding Dementia
Dementia is caused by a variety of neurological factors, and according to DSM-IV-
TR, each of these factors corresponds to a specifi c dementia diagnosis. Let’s review
the most common types of dementia: dementia of the Alzheimer’s type, vascular
dementia, and dementia due to other general medical conditions.Dementia of the Alzheimer’s Type
Almost three quarters of dementia cases are caused by Alzheimer’s disease (Plassman
et al., 2007). There is no routine lab test for diagnosing this disease at present,
and so this type of dementia is diagnosed by excluding or ruling out other possible
causes.