alzheimer dementia: the threshold between normal aging and disease

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Alzheimer’s Dementia The Threshold Between Normal

Aging and Disease

Garth Turner, MDJune 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