Abnormal Psychology

Cognitive Disorders 707

is called amyloid) that accumulate on the outer surfaces of neurons, particularly

neurons in the hippocampus (the brain area predominately involved in storing new

information in memory).

Researchers have not yet determined whether the neurofi brillary tangles and

plaquescause Alzheimer’s disease or are a by-product of some other process that

causes the disease (National Institute of Aging, 2003). However, neurofi brillary

tangles and amyloid plaques are generally discovered during autopsies, and PET

scanning that used a particular chemical marker has been able to detect the amyloid

plaques and neurofi brillary tangles that distinguish Alzheimer’s disease from other

causes of memory problems in living patients (Small et al., 2006). Additional studies

have corroborated the potential of such PET scanning to detect Alzheimer’s disease

(Ikonomovic et al., 2008). And other experimental biomedical tests have been de-

signed to identify biological markers that distinguish patients with Alzheimer’s. For

example, one test compares blood samples and cerebrospinal fl uid from patients

with Alzheimer’s disease, patients with dementia due to Parkinson’s disease (which

we will discuss shortly), and healthy control participants (Neale, 2008). Preliminary

studies using this test have been successful in distinguishing among the types of

participants.

Genetics

People who have a specifi c version of one gene, apo E, are more susceptible to late-

onset Alzheimer’s disease than those who don’t have this particular gene. However,

someone can have this version of the apo E gene and not develop Alzheimer’s; con-

versely, someone can develop Alzheimer’s and not have this version of the gene.

In contrast, early-onset Alzheimer’s is caused by mutation of one of three other

genes, and two of these mutations lead to Alzheimer’s disease in 100% of cases.

However, the third type of mutation, a rare form called presenilin 2, does not al-

ways cause the disease (Bird et al., 1996; Williamson-Catania, 2007), which sug-

gests that other neurological factors and/or psychosocial factors play a role.

Vascular Dementia

Vascular refers to blood vessels, and vascular diseases refer to problems with

blood vessels, such as high blood pressure or high cholesterol. Vascular disease can

reduce or block blood supply to the brain, which in turn can cause vascular de-

mentia. Blood vessels are involved in dementia in two possible ways: (1) plaque

Artist William Utermohlen learned in 1995 that

he had Alzheimer’s disease—which causes a type

of progressive dementia. He responded to the

news by painting self-portraits. Alzheimer’s can

specifi cally affect brain areas involved in spatial

abilities, which are crucial for painting. As his de-

mentia progressed, Utermohlen’s images became

less distinct and more abstract; these three por-

traits were done in (left to right) 1998, 1999, and

2000. Although he recognized that his paintings
      weren’t what he wanted, he said that he “could
      not fi gure out how to correct them” (Grady, 2006).

Galerie Beckel-Odille-Boicos Galerie Beckel-Odille-Boicos Galerie Beckel-Odille-Boicos

Amyloid plaques

Fragments of protein that accumulate on

the outside surfaces of neurons, particularly

neurons in the hippocampus.

Vascular dementia

A type of dementia caused by reduced or

blocked blood supply to the brain, which

arises from plaque buildup or blood clots.