Pseudodementia is a syndrome seen in older people in which they exhibit symptoms consistent with
dementiabut the cause is a pre-existing psychiatric illness rather than a degenerative one. [cite journal |last=Sachdev |first=Perminder|coauthors=J S Smith, H Angus-Lepan, P Rodriguez |year=1990 |title=Pseudodementia twelve years on|journal=J Neurol Neurosurg Psychiatry |volume=53 |issue=3 |pages=254–59 |pmid=2324757 |pmc=1014139 ] The name is derived from the Ancient Greekprefix "pseudo-" "false", prepended to "dementia".
Older people with predominant cognitive symptoms such as loss of memory, and vagueness, as well as prominent slowing of movement and reduced or slowed speech, were sometimes misdiagnosed as having dementia when further investigation showed they were suffering from a
major depressive episode. [cite journal |last=Caine |first=E.D.|year=1981 |title=Pseudodementia. Current concepts and future directions |journal=Archives of General Psychiatry |volume=38 |issue=12 |pages=1359–64 |id= |url= ] This was an important distinction as the former was untreatable and progressive and the latter treatable with antidepressanttherapy or electroconvulsive therapyor both.
The term was first coined in 1961 by psychiatrist Leslie Kiloh, who noticed patients with cognitive symptoms consistent with dementia who improved with treatment. His term was mainly descriptive. [cite journal |last=Kiloh |first=Leslie Gordon |authorlink=Leslie Gordon Kiloh |year= 1961|title=Pseudodementia |journal=Acta Psychiatr Scand.|volume=37|pages=336–51 |pmid=14455934]
Doubts about the classification and features of the syndrome, [cite journal |last=McAllister |first=TW|year=1983 |month=May |title=Overview: Pseudodementia |journal=American Journal of Psychiatry |volume=140 |issue=5 |pages=528–33 |pmid=6342420 ] and the misleading nature of the name, led to proposals that the term be dropped. [cite journal |last=Poon |first=Leonard W. |year=1991|title=Toward an understanding of cognitive functioning in geriatric depression |journal= International Psychogeriatrics |volume=4 |issue=4 |pages=241–66 |doi=10.1017/S1041610292001297 |url=http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=272114 abstract ] However, proponents argue that although it is not a defined singular concept with a precise set of symptoms, it is a practical and useful term which has held up well in clinical practice, and also highlights those who may have a treatable condition. [cite book |title=Dementia: Presentations, Differential Diagnosis, and Nosology |editor=V. Olga B. Emery, Thomas E. Oxman |author=Sachdev, Perminder & Reutens, Sharon|chapter=The Nondepressive Pseudodementias |year=2003 |publisher=JHU Press |isbn=0801871565 |pages=p. 418]
The history of disturbance in pseudodementia is often short and abrupt onset, while dementia is more often insidious. Clinically, people with pseudodementia differ from those with true dementia when their memory is tested. They will often answer that they don't know the answer to a question, and their attention and concentration are often intact, and they may appear upset or distressed. Those with true dementia will often give wrong answers, have poor attention and concentration, and appear indifferent or unconcerned. [cite journal |last=Wells |first=CE|year=1979 |month=May |title=Pseudodementia |journal=American Journal of Psychiatry |volume=136 |issue=7 |pages=895–900 |pmid=453349 ]
Investigations such as SPECT imaging of the brain show reduced blood flow in areas of the brain in people with
Alzheimer's Disease, compared with a more normal blood flow in those with pseudodementia. [cite book |title=Melancholia: A disorder of movement and mood: A phenomenological and neurobiological review |last=Parker |first=Gordon |authorlink=Gordon Parker |coauthors=Dusan Hadzi-Pavlovic, Kerrie Eyers |year=1996 |publisher=Cambridge University Press |location=Cambridge |isbn=052147275X |pages=pp. 273–74]
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