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MARCH 2012 M MEMORY LOSS ■■ 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. ■■ Alcohol or illicit drug intoxication ■■ 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. ■■ Brain growths (caused by tumors or infection) Memory is divided into three components: ■■ Brain infections such as Lyme disease, syphilis, or ■■ Short term memory HIV/AIDS ■■ Long term explicit memory ■■ Brain surgery, such as surgery to treat seizure disorders ■■ Implicit memory ■■ Cancer treatments, such as brain radiation, bone marrow transplant, or after chemotherapy Working memory or short-term memory is defined as the ■■ Certain medications temporary storage and processing of information. Short-term ■■ Certain types of seizures memory is the ability to remember information over a brief period ■■ Dementia of time, often seconds to minutes. The storage and processing ■■ Depression, bipolar disorder, or schizophrenia when functions of working memory are important for comprehension, symptoms have not been well controlled learning and reasoning. ■■ 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) ■■ Visual ■■ Electroconvulsive therapy (especially if it is long-term) ■■ Verbal ■■ Encephalitis of any type (infection, autoimmune disease, ■■ Spatial chemical/drug induced) ■■ Epilepsy that is not well controlled with medications Working memory is sensitive to age-related decline, although ■ ■ Head trauma or injury visual, verbal and spatial memory may be affected to differing ■■ Heart bypass surgery degrees. ■■ 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 ■■ Migraine headache such as time and place (episodic memory). ■■ Mild head injury or concussion ■■ 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) ■■ Permanent damage or injuries to the brain without conscious awareness of these previous experiences. ■■ Transient ischaemic attack (TIA) Amnesia is a form of memory loss and can be divided into: ■■ 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 ■■ Retrograde amnesia – when the person is unable to other symptoms that look like dementia. recall events during any injury or episode © Manrex Pty Ltd (ABN: 63 074 388 088) t/as Webstercare - 2012 Memory Loss, continued Medication causes of memory loss Medications most likely to cause memory loss include: ■■ Hypnotics ■■ Anticonvulsants ■■ Anxiolytics ■■ Antidepressants ■■ Analgesics ■■ 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: ■■ Strontium (Protos) ■■ 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