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Alzheimer's disease
Classification & external resources
Histopathologic image of senile plaques seen in the cerebral cortex in a patient with Alzheimer disease of presenile onset. Silver impregnation.
ICD-10 G30., F00.
ICD-9 331.0, 290.1
OMIM 104300
DiseasesDB 490
MedlinePlus 000760
eMedicine neuro/13
Alzheimer's disease (A.D), also known simply as Alzheimer's, is a neurodegenerative disease that, in its most common form, is found in people over age 65. Approximately 24 million people worldwide have dementia of which the majority (~60%) is due to Alzheimer’s.[1]

Clinical signs of Alzheimer's disease are characterized by progressive cognitive deterioration, together with declining activities of daily living and by neuropsychiatric symptoms or behavioral changes. It is the most common type of dementia. Plaques which contain misfolded proteins called beta amyloid are formed in the brain many years before the clinical signs of Alzheimer's are observed. Together, these plaques and neurofibrillary tangles form the pathological hallmarks of the disease. These features can only be discovered at autopsy and help to confirm the clinical diagnosis. Medications can help reduce the symptoms of the disease, but they cannot change the course of the underlying pathology.

The ultimate cause of Alzheimer's is unknown. Genetic factors are suspected, and dominant mutations in three different genes have been identified that account for the small number of cases of familial, early-onset AD. For the more common form of late onset AD (LOAD), ApoE is the only repeatedly confirmed susceptibility gene.

Auguste D.In 1901, Dr. Alois Alzheimer, a German psychiatrist, identified the first case of what became known as Alzheimer's disease, in a 50 year-old patient Auguste D and followed her to her death in 1906, when he first reported the case publicly.[2]

For most of the twentieth century, the diagnosis of Alzheimer's disease was reserved for individuals between the ages of 45 and 65 who developed symptoms of presenile dementia. Senile dementia, as a set of symptoms, was considered to be a relatively normal outcome of the ageing process, and thought to be due to age-related brain arterial "hardening."

In the 1970s and early-1980s, because the symptoms and brain pathology were identical for any age, the name "Alzheimer's disease" became used equally for afflicted individuals of all ages; however, the term senile dementia of the Alzheimer type (SDAT) was often used to describe the condition in those over 65. Eventually, the term Alzheimer's disease was formally adopted in medical nomenclature to describe individuals of all ages with the characteristic common symptom pattern, disease course, and neuropathology. The term Alzheimer disease (without the apostrophe and s) is also sometimes used in literature for learning.

Most cases of Alzheimer's disease are sporadic, ie, do not have familial inheritance. The latter comprising less than 10 percent incidences [3] The causes of the remainder are largely unknown.[4] but are accepted to be of multifactorial origin. Suggested causes include aluminum contamination, viruses eg herpes simplex I virus (HSV1), head trauma as well as defective DNA repair. In familial-inherited AD, genetic defects identified include mutations on Chromosomes 14 (in gene coding for Presenilins),[5] 19 (in gene coding for Apo E),[6] 21 (in gene coding for the Amyloid precursor protein or APP)[7] APP and Presenillin proteins in particular are associated with early-onset AD which forms about 5% of total Alzheimer's cases. Apo E is strongly linked to late-onset AD which may comprise up to 95% of cases.

The first readily identified symptoms of Alzheimer's disease are usually short-term memory loss and visual-spatial confusion. These initial symptoms progress from seemingly simple and often fluctuating forgetfulness and difficulty orienting oneself in space such as in a traffic lane while driving, to a more pervasive loss of short-term memory and difficulty navigating through familiar areas such as one's neighborhood, then to loss of other familiar and well-known skills as well as recognition of objects and persons.[8][9]

Since family members are often the first to notice changes that might indicate the onset of Alzheimer's they should learn the early warning signs and serve as informants during initial evaluation of patients clinically.[10] Aphasia, disorientation and disinhibition often accompany the loss of memory. Alzheimer's disease (AD) may also include behavioral changes, such as outbursts of violence or excessive passivity in people who have no previous history of such behavior.

In the later stages of the disease, deterioration of musculature and mobility, leading to bedfastness, inability to feed oneself, and incontinence, will be seen if death from some external cause (e.g. heart attack or pneumonia) does not intervene. Once identified, the average lifespan of patients living with Alzheimer's disease is approximately 7-10 years, although cases are known where reaching the final stage occurs within 4-5 years or at the other extreme they may survive up to 21 years.

Mild — In the early stage of the disease, patients have a tendency to become less energetic or spontaneous, though changes in their behavior often go unnoticed even by the patients' immediate family. This stage of the disease has also been termed Minor Cognitive Impairment (MCI), when the patient does not meet the criteria for a diagnosis of dementia.[11]

Moderate — As the disease progresses to the middle stage, patients might still be able to perform tasks independently (such as using the bathroom), but may need assistance with more complicated activities (such as paying bills).

Severe — As the disease progresses from the middle to the late stage, patients will not be able to perform even simple tasks independently and will require constant supervision. They become incontinent of bladder and then incontinent of bowel. They will eventually lose the ability to walk and eat without assistance. Language becomes severely disorganized, and then is lost altogether. They may eventually lose the ability to swallow food and fluid, and this can ultimately lead to death.

Alzheimer's disease (AD) is primarily a clinically diagnosed condition based on the presence of characteristic neurological and neuropsychological features and the absence of alternative diagnoses. Determination of neurological characteristics is made utilizing patient history and clinical observation, while neuropsychological evaluation includes memory testing and assessment of intellectual functioning over a series of weeks or months. Supplemental physical testing, including blood tests and neuroimaging, is utilized to rule out other diagnoses. Psychological testing, to include screening for depression and a mini mental state examination, can be helpful in establishing the presence and severity of dementia. Although certain clues from history may suggest a diagnosis of vascular dementias instead of, or in addition to, AD (for example, see the Hachinski scale [9]), the ability of certain neuroimaging modalities such as SPECT to differentiate vascular type from Alzheimer disease types of dementias, appears to be superior to clinical exam (PMID 15545324).

Interviews with family members and/or caregivers are also utilized in the initial assessment of the disease, as a patient with Alzheimer's may tend to minimize his or her symptoms, or may undergo evaluation at a time when his or her symptoms are less apparent, as quotidian fluctuations ("good days and bad days") are a common feature of the disease. Observations noting that a patient's good memory function decreases over time plays a critical role in the diagnosis of Alzheimer's.

No medical tests are available to diagnose Alzheimer's disease conclusively pre-mortem. Expert clinicians who specialize in memory disorders can now diagnose AD with an accuracy of 85 - 90%. However, a definitive diagnosis of Alzheimer's disease must await microscopic examination of brain tissue which generally occurs at autopsy.

Main article: Biochemistry of Alzheimer's disease

Biochemical characteristics
Alzheimer's disease has been identified as a protein misfolding disease, or proteopathy, due to the accumulation of abnormally folded amyloid beta protein and tau protein in the brains of AD patients.[12] Amyloid beta, also written Aß, is a short peptide that is a proteolytic byproduct of the transmembrane protein amyloid precursor protein (APP), whose function is unclear but thought to be involved in neuronal development.[13] The presenilins are components of a proteolytic complex involved in APP processing and degradation.[14] Although amyloid beta monomers are soluble and harmless, they undergo a dramatic conformational change at sufficiently high concentration to form a beta sheet-rich tertiary structure that aggregates to form amyloid fibrils[15] that deposit outside neurons in dense formations known as senile plaques or neuritic plaques, in less dense aggregates as diffuse plaques, and sometimes in the walls of small blood vessels in the brain in a process called amyloid angiopathy or congophilic angiopathy.

AD is also considered a tauopathy due to abnormal aggregation of the tau protein, a microtubule-associated protein expressed in neurons that normally acts to stabilize microtubules in the cell cytoskeleton. Like most microtubule-associated proteins, tau is normally regulated by phosphorylation; however, in AD patients, hyperphosphorylated tau accumulates as paired helical filaments[16] that in turn aggregate into masses inside nerve cell bodies known as neurofibrillary tangles and as dystrophic neurites associated with amyloid plaques.

Both amyloid plaques and neurofibrillary tangles are clearly visible by microscopy in AD brains.[17] At an anatomical level, AD is characterized by gross diffuse atrophy of the brain and loss of neurons, neuronal processes and synapses in the cerebral cortex and certain subcortical regions. This results in gross atrophy of the affected regions, including degeneration in the temporal lobe and parietal lobe, and parts of the frontal cortex and cingulate gyrus.[18] Levels of the neurotransmitter acetylcholine are reduced. Levels of the neurotransmitters serotonin, norepinephrine, and somatostatin are also often reduced. Glutamate levels are usually elevated.[19]

Three major competing hypotheses exist to explain the cause of the disease. The oldest, on which most currently available drug therapies are based, is known as the "cholinergic hypothesis" and suggests that AD is due to reduced biosynthesis of the neurotransmitter acetylcholine. The medications that treat acetylcholine deficiency have served to only treat symptoms of the disease and have neither halted nor reversed it.[20] The cholinergic hypothesis has not maintained widespread support in the face of this evidence, although cholingeric effects have been proposed to initiate large-scale aggregation[21] leading to generalized neuroinflammation.[18]

Research after 2000 includes hypotheses centered on the effects of the misfolded and aggregated proteins, amyloid beta and tau. The two positions differ with one stating that the tau protein abnormalities initiate the disease cascade, while the other believes that beta amyloid deposits are the causative factor in the disease.[22] The tau hypothesis is supported by the long-standing observation that deposition of amyloid plaques do not correlate well with neuron loss;[23] however, a majority of researchers support the alternative hypothesis that amyloid is the primary causative agent.[22]

The amyloid hypothesis is initially compelling because the gene for the amyloid beta precursor APP is located on chromosome 21, and patients with trisomy 21 - better known as Down syndrome - who thus have an extra gene copy almost universally exhibit AD-like disorders by 40 years of age.[24][25] The traditional formulation of the amyloid hypothesis points to the cytotoxicity of mature aggregated amyloid fibrils, which are believed to be the toxic form of the protein responsible for disrupting the cell's calcium ion homeostasis and thus inducing apoptosis.[26] A more recent and widely supported hypothesis suggests that the cytotoxic species is an intermediate misfolded form of amyloid beta, neither a soluble monomer nor a mature aggregated polymer but an oligomeric species.[27] Relevantly, much early development work on lead compounds has focused on the inhibition of fibrillization,[28][29][30] but the toxic-oligomer theory would imply that prevention of oligomeric assembly is the more important process[31] or that a better target lies upstream, for example in the inhibition of APP processing to amyloid beta.[32]

It should be noted further that ApoE4, the major genetic risk factor for AD, leads to excess amyloid build up in the brain before AD symptoms arise. Thus, beta-amyloid deposition precedes clinical AD.[33] Another strong support for the amyloid hypothesis, which looks at the beta-amyloid as the common initiating factor for the Alzheimer's disease, is that transgenic mice solely expressing a mutant human APP gene develop first diffuse and then fibrillar beta-amyloid plaques, associated with neuronal and microglial damage.[34][35][36]

Rare cases of Alzheimer's are caused by dominant genes that run in families. These cases often have an early age of onset. Mutations in presenilin-1 or presenilin-2 genes have been documented in some families. Mutations of presenilin 1 (PS1) lead to the most aggressive form of familial Alzheimer's disease (FAD).[37] Evidence from rodent studies suggests that the FAD mutation of PS1 results in impaired hippocampal-dependent learning which is correlated with reduced adult neurogenesis in the dentate gyrus.[38] Mutations in the APP gene on chromosome 21 can also cause early onset disease. The presenilins have been identified as essential components of the proteolytic processing machinery that produces beta amyloid peptides through cleavage of APP.

Most cases identified are "sporadic" with no clear family history. Environmental factors sometimes claimed to increase risk of Alzheimer's including prior head injury,[39] particularly repeated trauma,[40] previous incidents of migraine headaches,[41] exposure to defoliants,[41] and low activity levels during adulthood.[42] However, with the exception of previous concussion, none of these environmental risk factors are widely accepted.

Inheritance of the e4 allele of the ApoE gene is regarded as a risk factor for development of disease, but large-scale genetic association studies raise the possibility that even this does not indicate susceptibility so much as how early one is likely to develop Alzheimer's. There is speculation among genetic experts that there are other risk and protective factor genes that may influence the development of late onset Alzheimer's disease (LOAD). Researchers are investigating the possibility that the regulatory regions of various Alzheimer's associated genes could be important in sporadic Alzheimer's, especially inflammatory activation of these genes. These hypotheses include the amyloid-ß precursor protein (APP),[43] the beta secretase enzymes[44] insulin-degrading enzyme[45] endothelin-converting enzymes[46] and inflammatory 5-lipoxygenase gene.[47]

Alzheimer's disease is definitely linked to the 1st, 14th,[48] and 21st chromosomes, but other linkages are controversial and not yet confirmed. While some genes predisposing to AD have been identified, such as ApoE4 on chromosome 19, sporadic AD also involves other risk and protective genes still awaiting confirmation.

Alzheimer's disease is the most frequent type of dementia in the elderly and affects almost half of all patients with dementia. Correspondingly, advancing age is the primary risk factor for Alzheimer's. Among people aged 65, 2-3% show signs of the disease, while 25–50% of people aged 85 have symptoms of Alzheimer's and an even greater number have some of the pathological hallmarks of the disease without the characteristic symptoms. Every five years after the age of 65, the probability of having the disease doubles.[49] The share of Alzheimer's patients over the age of 85 is the fastest growing segment of the Alzheimer's disease population in the US, although current estimates suggest the 75-84 population has about the same number of patients as the over 85 population.[50]

Aging itself cannot be prevented, but the senescence of it can be mitigated. However, the evidence relating certain behaviors, dietary intakes, environmental exposures, and diseases to the likelihood of developing Alzheimer's varies in quality and its acceptance by the medical community.[51] It is important to understand that interventions that reduce the risk of developing disease in the first place may not alter disease progression after symptoms become apparent. Due to their observational design, studies examining disease risk factors are often at risk from confounding variables. Several recent large, randomized controlled trials—in particular the Women's Health Initiative—have called into question preventive measures based on cross-sectional studies. Some proposed preventive measures are even based on studies conducted solely in animals or in cell cultures but are not listed here.

Adults with damaged blood vessels in the brain or atrophy in their temporal lobe are more likely to develop Alzheimer's disease. It is known that blood vessel damage in the brain is more likely to occur in patients with high blood pressure, high cholesterol or diabetes. Therefore, prevention of these conditions can lower risk of developing Alzheimer's, as well as heart attack and stroke.

Intellectual stimulation (e.g., playing chess or doing crosswords)[52]
Regular physical exercise[53]
Regular social interaction [10]. Lonely individuals may be twice as likely to develop the type of dementia linked to Alzheimer’s disease in late life as those who are not lonely.
A Mediterranean diet with fruits and vegetables and low in saturated fat,[54] supplemented in particular with:
B vitamins[55] in particular, folic acid.[56][57][58][59]
Curry[60]
Omega-3 fatty acids, especially Docosahexaenoic acid[61][62]
Fruit and vegetable juice[63][64]
High doses of the antioxidant Vitamin E (in combination with vitamin C) seem to reduce Alzheimer's risk in cross sectional studies but not in a randomized trial and so are not currently a recommended preventive measure because of observed increases in overall mortality[65][66]
The moderate consumption of alcohol (beer, wine or distilled spirits) [67]
Cholesterol-lowering drugs (statins) reduce Alzheimer's risk in observational studies but so far not in randomized controlled trials[68]
Female Hormone replacement therapy is no longer thought to prevent dementia based on data from the Women's Health Initiative
Long-term usage of non-steroidal anti-inflammatory drugs (NSAIDs), used to reduce joint inflammation and pain, are associated with a reduced likelihood of developing AD, according to some observational studies.[69][70] The risks appear to outweigh the drugs' benefit as a method of primary prevention.[71]

Advancing age
ApoE epsilon 4 genotype (in some populations) [ ]
Environmental exposure to aluminum [11]
Head injury[72]
Poor cardiovascular health (including diabetes,[73] hypertension,[74] high cholesterol[75] and strokes)[76]
Smoking[77]

There is currently no cure for Alzheimer's disease. Currently available medications offer relatively small symptomatic benefit for some patients but do not slow disease progression. It helps a little for the memory. The American Association for Geriatric Psychiatry published a consensus statement on Alzheimer's treatment in 2006.[71]

Acetylcholinesterase inhibitors were thought to be important because there is a reduction in activity of the cholinergic neurons. AChE-inhibitors reduce the rate at which acetylcholine (ACh) is broken down and hence increase the concentration of ACh in the brain (combatting the loss of ACh caused by the death of the cholinergin neurons). Acetylcholinesterase-inhibitors seemed to modestly moderate symptoms but do not alter the course of the underlying dementing process.[78][79][80]

Examples include:

tacrine - no longer clinically used (formerly marketed as Cognex)
donepezil - (marketed as Aricept)
galantamine - (marketed as Razadyne in the U.S.A. Marketed as Reminyl or Nivalin in the rest of the world)
rivastigmine - (marketed as Exelon)
The three currently marketed products each comes in an oral form taken once or twice a day. Rivastigmine is also available as a once-daily transdermal patch.

There is some question as to the effectiveness of cholinesterase inhibitors. A number of recent articles have criticized the design of studies reporting benefit from these drugs, concluding that they have doubtful clinical utility, are costly, and confer many side effects.[81][82] The pharmaceutical companies, but also some independent clinicians, dispute the conclusions of these articles.

Examining over 52 studies conducted on Ginkgo for the treatment of "cognitive impairment and dementia," a Cochrane Review concludes that "there is promising evidence of improvement in cognition and function associated with Ginkgo." According to this review, the two randomized controlled studies that focused on Alzheimer's patients both showed significant improvement in these areas. [83] The AAGP review[71] did not recommend Ginkgo, nor did it warn against its use. A large, randomized clinical study in the US called the GEM study is now underway (fully enrolled), which examines the effect (or effects) of Ginkgo to prevent dementia. Results are expected in late 2007 or early 2008. [84]

Recent evidence of the involvement of glutamatergic neuronal excitotoxicity in Alzheimer's disease led to the development and introduction of memantine. Memantine is a novel NMDA receptor antagonist, and has been shown to be moderately clinically efficacious.[85] Memantine is marketed as Akatinol, Axura, Ebixa and Namenda.

Cognitive and behavioral interventions and rehabilitation strategies may be used as an adjunct to pharmacological treatment, especially in the early to moderately advanced stages of disease. Treatment modalities include counseling, psychotherapy (if cognitive functioning is adequate), reminiscent therapy, reality orientation therapy, and behavioral reinforcements as well as cognitive rehabilitation training.[86][87]

A large number of potential treatments for Alzheimer's disease are currently under investigation, including four compounds being studied in phase 3 clinical trials. Xaliproden had been shown to reduce neurodegeneration in animal studies.[88] Tramiprosate (3APS or Alzhemed) is a GAG-mimetic molecule that is believed to act by binding to soluble amyloid beta to prevent the accumulation of the toxic plaques. Tarenflurbil (MPC-7869, formerly R-flubiprofen) is a gamma secretase modulator sometimes called a selective amyloid beta 42 lowering agent. It is believed to reduce the production of the toxic amyloid beta in favor of shorter forms of the peptide.[89][90] Leuprolide has also been studied for Alzheimer’s. It is hypothesized to work by reducing luteinizing hormone levels which may be causing damage in the brain as one ages.[91]

Vaccines or immunotherapy for Alzheimer's, unlike typical vaccines, would be used to treat diagnosed patients rather than for disease prevention. Ongoing efforts are based on the idea that, by training the immune system to recognize and attack beta-amyloid, the immune system might reverse deposition of amyloid and thus stop the disease. Initial results using this approach in animals were promising, and clinical trials of the drug candidate AN-1792 showed results in 20% of patients. However, in 2002 it was reported that 6% of multi-dosed participants (18 of 300) developed symptoms resembling meningoencephalitis, and the trials were stopped. Participants in the halted trials continued to be followed, and 20% "developed high levels of antibodies to beta-amyloid" and some showed slower progression of the disease, maintaining memory-test levels while placebo-patients worsened. Microcerebral haemorrhages with passive immunisation and meningoencephalitis with active immunisation still remain potent threats to this strategy.[92] Work is continuing on less toxic Aß vaccines.

The statin simvastatin has been found to reduce the incidence of Alzheimer's disease and Parkinsons disease by almost 50 percent by resarchers from Boston University School of Medicine (BUSM).[93][94]

Proposed alternative treatments for Alzheimer's include a range of herbal compounds and dietary supplements. In the AAGP review from 2006,[71] Vitamin E in doses below 400 IU was mentioned as having conflicting evidence in efficacy to prevent AD. Higher doses were discouraged as these may be linked with higher mortality related to cardiac events.

Laboratory studies with cells and animals continually fuel the pipeline of potential treatments. Some currently approved drugs such as statins and thiazolidinediones[95] have also been under investigation for the treatment and prevention of Alzheimer’s. Recent clinical trials for Phase 2 and Phase 3 in this category have taken 12 to 18 months under study drug, plus additional months for patient enrollment and analysis. Compounds that are just entering into human trials or are in pre-clinical trials would be at least 4 years from being available to the public and would be available only if they can demonstrate safety and efficacy in human trials.

Modifications to the living environment and lifestyle of the Alzheimer's patient can improve functional performance and ease caretaker burden. Assessment by an occupational therapist is often indicated. Adherence to simplified routines and labeling of household items to cue the patient can aid with activities of daily living, while placing safety locks on cabinets, doors, and gates and securing hazardous chemicals and guns can prevent accidents and wandering. Changes in routine or environment can trigger or exacerbate agitation, whereas well-lit rooms, adequate rest, and avoidance of excess stimulation all help prevent such episodes.[96] Appropriate social and visual stimulation, however, can improve function by increasing awareness and orientation. For instance, boldly colored tableware aids those with severe AD, helping people overcome a diminished sensitivity to visual contrast to increase food and beverage intake.[97]

Alzheimer's is a major public health challenge since the median age of the industrialized world's population is increasing gradually.[98] Indeed, much of the concern about the solvency of governmental social safety nets is founded on estimates of the costs of caring for baby boomers, assuming that they develop Alzheimer's in the same proportions as earlier generations. For this reason, money spent informing the public of available effective prevention methods may yield disproportionate benefits.

The role of family caregivers has also become more prominent, as care in the familiar surroundings of home may delay onset of some symptoms and delay or eliminate the need for more professional and costly levels of care. However, home-based care may entail tremendous economic, emotional, and even psychological costs as well (see elderly care). Family caregivers often give up time from work and forego pay to spend 47 hours per week on average with an affected loved one who frequently cannot be left alone. From a survey of patients with long term care insurance, direct and indirect costs of caring for an Alzheimer's patient average $77,500 per year.[99]

Mohanlal in Thanmathra, a Malayalam (India) movie about the causes of AlzheimersIn the United States of America, AD was the 7th leading cause of death in 2004, with 65,829 number of deaths (and rising).[100]
At over $100 billion per year, AD is the third most costly disease in the U.S., after heart disease and cancer.[101]
There are an estimated 24 million people with dementia worldwide.[102] By 2040, it is projected that this figure will have increased to 81 million.
More than 5 million Americans are estimated to have Alzheimer’s disease.[103] It is projected that 14.3 million Americans will have the disease by mid-century: a 350 percent increase from 2000.[104]
The federal government estimates spending approximately $647 million for Alzheimer’s disease research in fiscal year 2005.[103]

Notable cases of Alzheimer's disease have included Former U.S. President Ronald Reagan, Harold Wilson, Iris Murdoch, Eddie Robinson, Ferenc Puskas, Rita Hayworth,[105] Eddie Albert, James Doohan, Claude Shannon, and Australia's Hazel Hawke.

TV documentaries Malcolm and Barbara - A Love Story(1999) and Malcolm and Barbara: Love’s Farewell (2007), featured Malcolm Pointon who was diagnosed with Alzheimer's at the age of 51. Over a period of 14 years Paul Watson followed Malcolm and Barbara Pointon's lives. The documentary follows the couple as Malcolm succumbs to the disease and shows the harsh reality faced by carers. The 2007 programme was the target of controversy when initial media claims that the finale purported to show Malcolm's death from the disease, but insider sources revealed that in the closing shots of the documentary actually show Malcolm slipping into a coma from which he never recovered. The argument overshadowed the importance of the documentary, and when it aired on 8th August 2007 the narrator informs us that "Malcolm is in a coma, and dies three days later."[106]

Thanmathra (Malayalam:Molecule) (2005) is a Malayalam film directed by Blessy which portrays the effects of Alzheimer's disease on the life of an individual and his family.

Iris is a 2001 film that tells the story of Irish novelist Iris Murdoch and her relationship with John Bayley. The film contrasts the start of their relationship and their later life, when Murdoch (played by Dame Judi Dench) was suffering from Alzheimer's disease. The film is based on Bayley's memoir Elegy for Iris.