Dementia is one of the most dreaded human conditions, both by those observing it and by those experiencing it. It is defined as a persistent and progressive impairment of intellectual function, and can affect memory, emotions, personality, language, judgment, and cognition. It is frequently associated with other medical conditions, including Alzheimer’s disease, stroke, and spongiform encephalopathies.

Encephalopathies are diseases of the brain. The spongiform encephalopathies are named for their characteristic deterioration of central nervous system tissue, resulting in a sponge-like appearance of the brain. They include kuru, Creutzfeldt-Jacob disease (CJD), Gerstmann-Straussler-Scheinker (GSS) disease, and familial fatal insomnia (FFI). Unlike Alzheimer’s disease and strokes, the spongiform encephalopathies can be transmissible. Transmission of dementia was originally thought to be due to a virus; however, subsequent information suggests that the agent of transmission is simply a protein, with no associated nucleic acid. These proteins were termed prions, and are normal proteins found primarily in a sponge-like tissue. Disease is associated with abnormal versions of prion proteins.

The normal function of prion proteins is unclear, but they are thought to protect critical brain cells from dying. Mice that lack normal prions develop ataxia (coordination problems) that resembles the ataxia of kuru and CJD patients. Prion-free mice develop symptoms at approximately 70 weeks (late middle age for a mouse).

Since proteins are unable to self- replicate, it seemed unlikely that a transmissible disease could be caused by protein alone. Contact between the normal and abnormal forms of protein can cause conformational change from the normal to the flawed form, if the abnormal and normal proteins are sufficiently similar. Encephalitis (inflammation of the brain) can present with similar initial symptoms as the spongiform encephalopathies, most notably ataxia and mental disorientation. Encephalitis can have several causes, some of which are viral infections.

All of the following individuals display symptoms of dementia EXCEPT someone who:

a. cannot do the most rudimentary arithmetic operations.

b. cannot distinguish between the smells of the distinct flowers.

c. displays abrupt change in character.

d. has lost the ability to speak.

e. has tremendous difficulty remembering the days of the week.


According to the passage, which one of the below is a medical condition that is the least likely to be associated with dementia:

a.Alzheimer's disease

b. Familial fatal insomnia

c. Stroke

d. Meningitis

e. Spongiform encephalopathies


Spongiform encephalopathies are different from strokes because spongiform encephalopathies:

a. are more difficult to cure.

b. have more varieties.

c. are less researched.

d. are associated with human brain.

e. are transmissible.