Abnormal Psychology

710 CHAPTER 15

This form of dementia is most common among young males, who are more likely

to engage in risk-taking behaviors (including reckless drinking). In some cases, the

dementia is caused by a single trauma to the head (such as a car accident) and is un-

likely to get worse; when the dementia is caused by multiple traumas (as occurs with

boxers) it may become worse over time (American Psychiatric Association, 2000).

Substance-Induced Persisting Dementia

When the cognitive defi cits of dementia are caused by substance use but persist be-

yond the period of intoxication or withdrawal, the clinician makes the diagnosis of

substance-induced persisting dementia. A patient who receives this diagnosis usually

has a long history of substance dependence, and symptoms rarely occur in patients

younger than 20 years old. The onset is slow, as is the progression of defi cits—the

fi rst symptoms arise while the person has substance dependence. The defi cits are

often not reversible and may even get worse when the substance use is discontinued,

although there are exceptions (American Psychiatric Association, 2000).

As we’ve noted, dementia may be caused by any number of medical illnesses or

conditions, and these causes are not mutually exclusive; in a given individual, de-

mentia may have more than one cause. For example, someone may have both vas-

cular dementia and Alzheimer’s disease. When this occurs, the clinician diagnoses

each type (cause) separately. Table 15.12 summarizes key facts about the different

types of dementia.

Dementia due to... Approximate percentage

of dementia cases

Prognosis/Course Onset Gender difference

Alzheimer’s Disease 70% Poor Gradual, often after age

65; early onset is rare.

Slightly more common among

females than males

Vascular Disease 15% (often comorbid with

Alzheimer’s type)

Cognitive loss may remain

stable or worsen in a

stepwise fashion.

Abrupt; earlier age of onset

than Alzheimer’s

More common among men

Lewy Bodies 15% (can be comorbid with

Alzheimer’s type)

Poor Gradual; age of onset is

between 50 and 85.

Slightly more common among men

than women

HIV Infection Less than 10% Poor unless treated with

antiretroviral medication

Gradual; depends on age

at which HIV infection is

acquired

Estimates of sex ratios vary,

depending in part on the sex

difference in HIV prevalence and the

availability of antiretroviral treatment

at the time a study is undertaken.

Parkinson’s Disease Less than 10%; often

comorbid with Alzheimer’s

type and/or vascular

dementia; about 50% of

patients with Parkinson’s

disease develop dementia.

Poor Gradual; typical age of

onset is in the 70s.

More men than women develop

Parkinson’s disease, and so men are

more likely to develop this type of

dementia.

Huntington’s Disease Less than 10% Poor Gradual; onset usually

occurs in the 40s or 50s.

No sex difference

Head Trauma Unknown Depends upon the specifi c

nature of the trauma

Usually abrupt, after the

head injury

Unknown, but most common among

young males

Substance-Induced Unknown Variable, depends on the

specifi c substance and

defi cits

Gradual; in the 30s and

beyond

Unknown

Note: Most cases of dementia are caused by Alzheimer’s disease. However, dementia in a given individual can arise from more than one cause, and the percentages in the second column

refl ect these comorbidities; for this reason, the numbers add up to more than 100%.

Table 15.12 • Key Facts About Different Types of Dementia