Explains how physicians differentiate between normal forgetfulness and diseases that affect cognition such as Alzheimer dementia.

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Alzheimer’s Dementia
The Threshold Between Normal Aging and Disease
Garth Turner, MD
June 20, 2013

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Outline
i. “What do you expect, I’m 82 years-old?”
ii. A clinician’s approach to cognitive
complaints
iii. A quick review of Alzheimer’s dementia

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Normal aging
• Many, but not all cognitive functions
naturally decline with age
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• Our cognitive abilities appear to peak in our
20s and thereafter, there is slow and subtle
decline
• Perhaps the earliest cognitive ability to decline
is processing speed
• People are not inclined to notice or be
concerned about changes to their cognition
before their 40s.
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Normal aging

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• Memory

The most common cognitive complaint as we age

Disproportionate decline in short-term memory (the
ability to recall new information shortly after it is
presented)

Whereas younger people tend to remember recent
events more easily than remote events, older people tend
to remember remote events more readily than recent
events
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Normal aging

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• Memory

Do not tend to lose autobiographical
information

Memory of factual information and general
word knowledge is relatively resistant to aging

Do not tend to lose learned skills, but rate of
new skill learning in older adults is slower
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Normal aging

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• Attention

Decline in the ability to filter nonessential or irrelevant
information when selective attention is required

Performance decline for tasks requiring divided attention

Sustained attention is relatively unaffected
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Normal aging

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• Language

Increased difficulty retrieving names of
people, places, and objects (“tip of the tongue”
phemonenon)

Rate of verbal output (fluency) declines with
age
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Normal aging

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• Executive function

Effectively allows us to plan and organize our way
through the day

Requires intact attention, mental manipulation of
learned material, abstraction, and adaptation

As we age, there is a relative decline in mental
flexibility and tendency towards perseveration

We develop an increasingly rigid or concrete
approach to reasoning
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Normal aging

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Outline
iii. A quick review of Alzheimer’s disease
i. What do you expect, I’m 82 years-old?
ii. A clinician’s approach to cognitive
complaints

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Clinical assessment
• History is paramount
• Always helpful to obtain information from
an independent observer who knows the
patient well as persons with dementia are
often unaware of their impairments
• Important to understand the rapidity of
onset and decline. An insidiously
developing process is more often typical of
dementia.
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• Cognitive complaints (e.g. memory, language,
visuospatial function)
• Psychiatric symptoms (apathy, depression, anxiety,
insomnia, fearfulness, paranoia, hallucinations)
• Personality changes (changes to temper,
impulsiveness, disinterest)
• Problem behaviors (wandering, agitation, out of bed
at night)
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Clinical assessment

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• In addition to cognitive complaints, your clinician wants
to know if there has been a functional impairment
• Instrumental activities of daily living (IADLs)

Housework (e.g. housekeeping, cooking)

Adherence to medications

Managing money, paying bills

Shopping

Telephone / communication

Transportation
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Clinical assessment

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• After acquiring the history (subjective), your
clinician will make both a
neuropsychological and a physical
assessment (objective)
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Clinical assessment

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• Neuropsychological assessment

Attention

Memory

Executive function

Language

Visuospatial function
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Clinical assessment

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• Determinations

Are the cognitive complaints disproportionate to age?

Could the cognitive complaints be a consequence of a
non-neurologic condition (e.g. medical illness,
medication effect)?

Are the history, neuropsychological examination, and
physical examination concordant and consistent with a
syndromic dementia (e.g. Alzheimer’s disease)?
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Clinical assessment

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• As a matter of standard practice, we routinely
look for relatively common causes of “reversible
dementia”

B12 deficiency

Thyroid dysfunction

Anatomical changes (MRI or CT brain)
• Additional tests may be included as clinically
indicated
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Clinical assessment

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• Adjunct testing (not standard)

Referral for neuropsychological testing

Lumbar puncture (biomarkers)

Positron emission tomography (PET)
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Clinical assessment

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Outline
iii. A quick review of Alzheimer’s disease
i. What do you expect, I’m 82 years-old?
ii. A clinician’s approach to cognitive
complaints

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• 1 in 8 people age 65 and older has AD
• 45% of persons over age 85 have AD
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Alzheimer’s disease

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Alzheimer’s disease

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• Hallmark and early feature of typical
Alzheimer’s disease is a decline in verbal
and visual “episodic memory” (memories tied
to experiences, e.g. what you ate for dinner)
• Progressive decline in other
neuropsychological domains (e.g. executive
function, language, visuospatial) and ability
to carry out IADLs
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Alzheimer’s disease

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• Accumulation of extraneuronal amyloid
plaques (amyloid beta) and intraneuronal
neurofibrillary tangles (tau)
• Neuronal death
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Alzheimer’s disease

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Alzheimer’s disease

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• Mild cognitive impairment (MCI)

Subjective decline in memory or other cognitive
dysfunction

Greater than expected for age

No functional impairment (IADLs)
• Approx 80% of individuals with amnestic MCI
will convert to Alzheimer’s disease within 6
years (a “preclinical” state)
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The “gray zone”
“g

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• Alzheimer’s disease (AD)
• Frontal temporal lobar dementia (FTLD)
• Vascular dementia (VaD)
• Dementia with Lewy Bodies (DLB)
• Parkinson’s disease with dementia (PDD)
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Major syndromic dementias

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Thank you
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• Sirven, IJ and Malamut, BL. (2008). Clinical
Neurology of the Older Adult. Philadelphia:
Lippincott Williams & Wilkins.
• 2012 Alzheimer’s Disease Facts and Figures.
Alzheimer’s Association
( http://www.alz.org/downloads/facts_figures_2012.
pdf )
• Video: Inside the brain: unraveling the mystery of
Alzheimer’s disease. National Institute on Aging
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References