|
EVOLUTIONARY
CLASSIFICATION
DISORDER: Cognitive
|
Archetypal
Disruption
Disorders
of:
|
|
A
Attachment/
Affiliation Archetype
|
B
Hierarchical/
Ranking Archetype
|
C
Courtship/ Mating
Archetype
|
D
Threat Response Archetype
|
|
|
1.
Malf-
unction
|
1.1
Modular
|
1.1A |
1.1B
|
1.1C
|
1.1D
|
|
1.2
Integrative
|
1.2A
|
1.2B
|
1.2C
|
1.2D
|
|
2.
Dys-
regulation
|
2.1
Environmental Uniqueness
|
2.1A
|
2.1B
|
2.1C
|
2.1D |
|
2.2
Maladaptive Meme
|
2.2A
|
2.2B
|
2.2C
|
2.2D
|
|
3.
Sociability
|
3.1
By-product (trade off) |
3.1A
|
3.1B
|
3.1C
|
3.1D
|
3.2
Defense |
3.2A |
3.2B |
3.2C |
3.2D |
Dementia of the Alzheimer's type (DAT)
1.2B-D
(As a Disorder of
Integration)
Emery
(2004) suggests that there is a phylogenetic hierarchical deterioration in DAT memory,
a process for which she coins the term "retrophylogenesis",
because memory structures last to evolve are the first to
deteriorate in DAT. She has developed a threetiered evolutionary model of memory,
with each tier originating in a different period of phylogenetic history:
Tier 1: Lowest Evolutionary Tier - Motor (Subcortical,
Movement) Memory
Tier 2: Middle Evolutionary Tier - Emotional Memory
Tier 3: Highest Evolutionary Tier - Neocortical Memory
Emery notes that memory is the result of integrated
neuronal networks involving the formation of new synaptic
connections between neurons (Black & Greenough 1998) and can be viewed
as a specific form of neural plasticity (Almkvist 2000; Gluck & Myers
1998). Memory is a critical adaptational
tool enabling an organism to retain information so that every minute of
existence won't require a de novo response to same or similar challenges.
Phylogenetically, human memory appears to be a product of modified old brain
parts and newer brain parts working together, having evolved over millions of
years of phylogenetic history (Darwin 1859; Dobzhansky 1964; Guyton 2000).
Because DAT is a cortical dementia, motor memory (subserved
predominantly by subcortical-frontal and cortico-striatal substrates) is impacted
less and deteriorates later, so that patients retain ability for motor-based
skills longer than for higher neocortical skills.
Emotional memory is an evolved mechanism to aid avoidance
of things previously proven dangerous and aid approach to things proven to favor
survival. The few studies that exist find there are not significant differences
between DAT patients and normal controls in actual emotional arousal. However,
there are significant differences between DAT patients and normal elderly in
both ability to remember and ability to interpret the factual context of
emotional arousal (Mori 1999). Even while DAT patients can no longer remember
the facts of an emotional event, the emotions remain; this is an example of
retrophylogenesis whereby neocortical memory is lost but emotional memory
remains.
Regarding neocortical memory, Emery notes that
the greatest and earliest DAT memory
deficits occur in this phylogenetic tier latest to develop in evolutionary
history.
home
[ Classification Grid ]
Citation suggestion: Dr Gary Galambos, Cognitive Disorders, Evolutionary
Psychiatry Home Sydney Australia (http://www.ep.org.au/dis/cog.htm)
[date accessed]
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M.B.B.S. F.R.A.N.Z.C.P.
Page last updated: 05 September 2006
