Although it is general, true dementia always affects specific aspects of mental function - such things as: memory, abstract thinking: reasoning and ability to calculate. The lower part of this page lists signs of those kinds of impairments that other people may notice, and simple tests.

• When a person has dementia, something has been lost, this diagnosis always implies a decline in function.
  • That's different than, say, mental retardation - where a person has never reached a normal or superior level of these abilities.
  • It's also different than a "personality trait". The absent minded professor who has been misplacing his keys since second grade is not the same as the prison warden who now keeps leaving the key in his office door.
• Since the qualities that are lost in dementia are so very human, their loss is particularly devastating to the person who is aware of the decline and to those around him.
  • Dementia strikes at the essential qualities of a person, the things make a people who they are, and so - unless very early and limited, dementia easily results in the inability to continue to live among family, and to retain a network of friends.
  • Sometimes there is a ctastrophic event in the demented person life, when she or he is suddenly faced with the decline. This might happen in a store if suddenly that person just cannot count up the right amount of money, or cannot find the shopping cart just left in the aisles. Realization of the loss of ability can result in agitation and an incident calling for police or paramedic intervention.

Senility is commonly used as a synonym for dementia.

• Although elderly people can (and do) retain excellent intellectual skills, very great age is so often associated with dementia that the term senile commoly denotes the kind of short-term memory loss and personality change that is common to very old people from a combination of factors, is an English language term for dementia in old age.
• In medicine, "senility" is called senile dementia, and has been distinguished from so-called presenile dementia- that is, the same kind of impairment that is sometimes seen in much younger people.

The truth is that the same specific causes of re-senile dementia sometimes account for the other kind - and vice-versa.

One reason that dementia is broken up into "senile" and "pre-senile" categories is because the statistical odds of a specific cause (or set of causes) being the culprit changes according to age group. Even so- the very old person can be suffering from a usual cause of dementia in a middle-aged adult, and the middle-aged adult can be impaired by causes more typically found in the very elderly. Finding the cause for any individual is much more likely to be successful if simple formulas that apply to groups are not relied on, but instead a good doctor actually investigates the individual case.

The specific cause of dementia is very important to understand. That's because the future of the person showing signs of dementia can be predicted, and sometimes changed with treatment, depending on the reason that higher brain functions are impaired.

• There are infections of the central nervous system - like bacterial infection from the two different spirochetes that cause syphylis and Lyme Disease that can mimic signs of senile dementia.
  • The signs of dementia are usually manifest only in the late stage of these infections, and so - since the primary infection may have ocurred years or even decades before, laboratory testing is a reasonable to rule out these treatable causes of memory loss and decline in intellectual function even without a known history of high risk sexual behavior, tick bite, or past history of either infection.
  • Antibiotics if given in the right form, and the right dose can improve matters and stop the decline.
• Low blood oxygen (hypoxia) can also mimic signs of dementia, and worsen brain function so that even people with actual dementia perform way below potential.
• Severe clinical depression can also both mimic dementia in people who do not have it , and markedly increase its signs in people who do have it.

Head trauma

Stroke

Alcoholism

B12 Deficiency (sometimes associated with alcoholism)

Thyroid Hormone Deficiency

AIDS

Subdural Hematoma

Cannot find way home to long-established residence
Cannot find way within long-established residence
Can't state names of grown children

• Chapter 156 – Dementia (DSM-IV-TR #290.40–290.44, 294.10, 294.11, 294.8) in Moore & Jefferson: Handbook of Medical Psychiatry, 2nd ed. Mosby 2004 ISBN 0-323-02911-6
• Vicosio BA: Dementia: when is it not Alzheimer’s disease?. The American Journal of the Medical Sciences 2002; 324:84-95

• Dementia- What are the common signs?