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MARCH 2012
M
MEMORY LOSS
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Transient global amnesia – when a person experiences
emory loss is common in older people. Memory loss,
especially delayed recall, can signal the onset of abrupt onset of severe anterograde amnesia from which the
dementia and often leads to institutionalisation and a patient usually recovers within hours except for the memory gap
decrease in the quality of life.
for the duration of the episode
Chronic conditions such as hypertension, diabetes, and depression
have an impact on memory loss. Diet plays a significant role in
the development of memory loss and cognitive decline through
its impact on chronic diseases. Many medications may cause
memory loss, which is usually reversible upon cessation of the
drug.
Amnesia can also be divided into long-term amnesia or shortterm (or transient) amnesia.
Prevalence
Causes of memory loss
Mild cognitive impairment (MCI) is a transitional zone between
normal cognitive function and dementia. People with MCI convert
to dementia at a greater rate than other older adults.
Most older people living in the community with memory loss do Whilst normal ageing may lead to trouble learning new material
not have dementia. People with mild cognitive impairment are or requiring a longer time to remember learned material, there are
at increased risk of progressing to dementia, but many will never many causes of memory loss:
develop dementia.
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Alcohol or illicit drug intoxication
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An event in which not enough oxygen was going to
Definitions
Memory is defined as the ability to store, retain and recall the brain (heart stopped, stopped breathing, complications from
receiving anesthesia)
information.
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Brain growths (caused by tumors or infection)
Memory is divided into three components:
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Brain infections such as Lyme disease, syphilis, or
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Short term memory
HIV/AIDS
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Long term explicit memory
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Brain surgery, such as surgery to treat seizure disorders
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Implicit memory
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Cancer treatments, such as brain radiation, bone marrow
transplant,
or after chemotherapy
Working memory or short-term memory is defined as the
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Certain medications
temporary storage and processing of information. Short-term
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Certain types of seizures
memory is the ability to remember information over a brief period
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Dementia
of time, often seconds to minutes. The storage and processing
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Depression, bipolar disorder, or schizophrenia when
functions of working memory are important for comprehension,
symptoms have not been well controlled
learning and reasoning.
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Dissociative disorder (not being able to remember a
major, traumatic event; the memory loss may be short-term or
Working memory can be described as three distinct tasks:
long-term)
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Visual
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Electroconvulsive therapy (especially if it is long-term)
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Verbal
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Encephalitis of any type (infection, autoimmune disease,
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Spatial
chemical/drug induced)
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Epilepsy that is not well controlled with medications
Working memory is sensitive to age-related decline, although
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Head trauma or injury
visual, verbal and spatial memory may be affected to differing
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Heart bypass surgery
degrees.
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Illness that results in the loss of, or damage to, nerve
cells
(neurodegenerative
illness), such as Parkinson’s disease,
Long term memory involves facts taken out of context or
semantic memory, and information specific to a particular context, Huntington’s disease, or multiple sclerosis
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Migraine headache
such as time and place (episodic memory).
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Mild head injury or concussion
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Nutritional problems (vitamin deficiencies such as low
Implicit memory or procedural memory is a type of memory
in which previous experiences aid in the performance of a task vitamin B12)
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Permanent damage or injuries to the brain
without conscious awareness of these previous experiences.
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Transient ischaemic attack (TIA)
Amnesia is a form of memory loss and can be divided into:
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Anterograde amnesia – when the person cannot Older adults are particularly susceptible to dehydration. Severe
memorise new information
dehydration can cause confusion, drowsiness, memory loss, and
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Retrograde amnesia – when the person is unable to other symptoms that look like dementia.
recall events during any injury or episode
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Memory Loss, continued
Medication causes of memory loss
Medications most likely to cause memory loss include:
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Hypnotics
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Anticonvulsants
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Anxiolytics
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Antidepressants
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Analgesics
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Antipsychotic drugs
Analysis of a large French database over 10 years shows zolpidem
(Stilnox), topiramate, zopiclone (Imovane), alprazolam (Xanax,
Kalma), and bromazepam (Lexotan) are most often associated
with memory disorders.
Alprazolam and zolpidem can produce anterograde amnesia,
with the risk increasing with dosage.
Among the antidepressants amitriptyline (Endep) tends to
produce more anticholinergic adverse effects more frequently.
If a tricyclic antidepressant is indicated in an older person
nortriptyline (Allergan) has the least anticholinergic activity,
with similar efficacy.
Benzodiazepines (e.g. alprazolam, clonazepam) and
anticholinergic agents are mainly responsible for short-term
amnesia.
The newer anticonvulsants, such as gabapentin (Neurontin)
and pregabalin (Lyrica), frequently cause amnesia and memory
disorders. They are prescribed for seizures as well as for the
treatment of neuropathic pain, post-herpetic neuralgia and diabetic
neuropathy. Pregabalin has been associated with impairments in
episodic memory of verbal and visual information. Topiramate
alters short-term memory.
Other medications associated with memory loss include:
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Strontium (Protos)
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Statins (atorvastatin, simvastatin, rosuvastatin,
fluvastatin, pravastatin)
Memory loss and statins
There are anecdotal reports of loss of memory and other
cognitive functions with excessive cholesterol lowering. Some
patients have trouble recalling words, or experience confusion
and memory loss with cholesterol-lowering statins within days
to months of starting therapy.
If a resident complains of memory loss soon after commencing
on a statin, consider holding the statin for one to three months,
and monitor for improvement. Withholding a statin for up to six
weeks does not appear to increase the risk of cardiac events in
stable patients.
Switching to another statin may be suggested if holding a statin
is not an option (e.g. unstable heart disease, acute coronary
syndrome). Alternatively, a non-statin lipid lowering agent such
as fish oils or fibrates (fenofibrate, gemfibrozil) could be tried if
appropriate.
Memory loss with diabetes
Diabetes appears to be a risk factor for developing mild to
moderate cognitive dysfunction and all types of dementia.
Cognitive decline appears to be associated with poor glycaemic
control or resultant microvascular damage.
© Manrex Pty Ltd (ABN: 63 074 388 088) t/as Webstercare - 2012
Executive functioning may also be affected. This involves
problem solving, planning, organisation, insight, reasoning and
attention.
Memory loss and depression
Whether depression is a risk factor or a result of memory loss is
unclear. Depression can mimic the signs of memory loss. Many
antidepressants cause memory loss.
Management
Medication-induced memory loss is mostly reversible upon
cessation of the drug.
Protective lifestyle factors besides regular physical exercise
and healthy diet, include frequent mental activity and stress
reduction.
In people with Alzheimer’s disease treatment with cholinesterase
inhibitors such as donepezil (Aricept), galantamine (Reminyl,
Galantyl) and rivastigmine (Exelon) may provide symptomatic
relief and enhance quality of life, but do not appear to alter
progression of the disease. Cholinesterase inhibitors and
memantine (Ebixa, Memanxa, Memantine) show, at best, modest
efficacy in improving cognition and/or reducing the rate of
cognitive and functional decline.
Donepezil, rivastigmine and galantamine seem to have similar
efficacy, but at full dose oral rivastigmine may have more GI
adverse effects.
Memory clinics
Memory clinics provide a team-based assessment of people
with memory loss. There is some evidence that memory clinics
improve the quality of life of carers and improve the assessment
of people with dementia.
Summary
Older persons, especially those with dementia, are at risk
because of the frequent and substantial effects of medications on
their memory. The benefit-risk ratio must be evaluated regularly
and non-essential treatments withdrawn or reduced.
References
Australasian Journal on Ageing 2006;25:14-19.
British Journal of Clinical Pharmacology 2011;72:898-904.
Journal of Primary Care & Community Health June 1, 2011.
Medline
Plus
http://www.nlm.nih.gov/medlineplus/ency/
article/003257.htm