[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Alzheimer disease [Conditions](https://durgical.com/en/conditions/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) # Alzheimer disease Alzheimer disease is the most common cause of dementia; it usually starts with forgetting recent events and slowly affects language and daily life. Updated 2026-10-29 ## Structures involved Tap one to see what it is and open it in 3D. - [Hippocampus](https://durgical.com/en/anatomy/hippocampus/) - [Temporal lobe](https://durgical.com/en/anatomy/middle-temporal-gyrus/) - [Parietal lobe](https://durgical.com/en/anatomy/superior-parietal-lobule/) - [Cingulate gyrus](https://durgical.com/en/anatomy/cingulate-gyrus/) - [Frontal lobe](https://durgical.com/en/anatomy/superior-frontal-gyrus/) - [Amygdala](https://durgical.com/en/anatomy/amygdaloid-body/) - [Fornix](https://durgical.com/en/anatomy/fornix/) - [Lateral ventricles](https://durgical.com/en/anatomy/lateral-ventricle/) ## In biochemistry - [Apolipoprotein E (ApoE)](https://durgical.com/en/biochemistry/enzymes/apolipoprotein-e/) - [Molecular chaperones and heat shock proteins](https://durgical.com/en/biochemistry/topics/molecular-chaperones-and-heat-shock-proteins/) - [Ubiquitin–proteasome system](https://durgical.com/en/biochemistry/topics/ubiquitin-proteasome-system/) - [Protein structure and folding](https://durgical.com/en/biochemistry/topics/protein-structure-and-folding/) - [Prion protein (PrP)](https://durgical.com/en/biochemistry/enzymes/prion-protein/) ## In histology - [The neuron and synapse](https://durgical.com/en/histology/the-neuron-and-synapse/) ## In the clinical exam - [Mental status: orientation, attention and screening tests](https://durgical.com/en/clinical-exam/mental-status-orientation-attention-and-screening-tests/) ## In physiology - [The main neurotransmitters](https://durgical.com/en/physiology/the-main-neurotransmitters/) - [Learning and memory](https://durgical.com/en/physiology/learning-and-memory/) - [Taste and smell](https://durgical.com/en/physiology/taste-and-smell/) - [The limbic system, emotion and reward](https://durgical.com/en/physiology/the-limbic-system-emotion-and-reward/) - [The cerebral cortex and language](https://durgical.com/en/physiology/the-cerebral-cortex-and-language/) ## Why it happens - [Intracellular accumulations: cholesterol, proteins, hyaline, glycogen](https://durgical.com/en/general-pathology/intracellular-accumulations-cholesterol-proteins-hyaline-glycogen/) - [How organs age: normal changes vs disease](https://durgical.com/en/general-pathology/how-organs-age-normal-changes-vs-disease/) - [Endoplasmic reticulum stress and the unfolded protein response](https://durgical.com/en/general-pathology/endoplasmic-reticulum-stress-and-the-unfolded-protein-response/) - [Atrophy](https://durgical.com/en/general-pathology/atrophy/) - [Autophagy](https://durgical.com/en/general-pathology/autophagy/) - [Trisomies 21, 18 and 13, and the 22q11.2 deletion](https://durgical.com/en/general-pathology/trisomies-21-18-and-13-and-the-22q11-2-deletion/) ## Show 3 more - [Cellular aging: telomeres, DNA damage, senescence and proteostasis](https://durgical.com/en/general-pathology/cellular-aging-telomeres-dna-damage-senescence-and-proteostasis/) - [Apoptosis: the intrinsic and extrinsic pathways](https://durgical.com/en/general-pathology/apoptosis-the-intrinsic-and-extrinsic-pathways/) - [Multifactorial (complex) disorders](https://durgical.com/en/general-pathology/multifactorial-disorders/) ## What it is A progressive neurodegenerative disease and the most common cause of dementia. It typically begins with loss of recent memory and gradually affects language, orientation, judgement and daily function. ## Who gets it Frequency rises steeply with age and it is more common in women, partly because they live longer. Latin America is ageing quickly, so dementia is a growing public health problem; a large family with an early-onset genetic form (PSEN1) has been studied in Antioquia, Colombia. ## Causes - Mostly late-onset sporadic disease from ageing plus genetic and vascular factors - APOE ε4 allele: the main genetic risk factor for late onset - Rare autosomal dominant early-onset forms (APP, PSEN1, PSEN2) - Down syndrome (extra copy of the APP gene) ## Risk factors - Older age - Family history and APOE ε4 - Hypertension, diabetes and obesity in midlife - Low education, physical inactivity, smoking - Hearing loss, depression and social isolation - Traumatic brain injury ## Pathophysiology Amyloid-beta builds up outside neurones as plaques and tau protein forms neurofibrillary tangles inside them. Synapses and neurones are lost, beginning in the entorhinal cortex and [hippocampus](https://durgical.com/en/anatomy/hippocampus/) and spreading to temporal, parietal and frontal association cortex. Cholinergic transmission falls, and the brain shrinks with widened sulci and enlarged ventricles. ## Classification - Preclinical (biomarkers only) - Mild cognitive impairment due to Alzheimer disease - Dementia: mild, moderate and severe - Early onset (before about 65) and late onset ## Symptoms and signs - Difficulty learning and recalling recent information (repeats questions, misplaces things) - Word-finding difficulty - Getting lost and disorientation in time and place - Poor judgement, difficulty planning and managing money or medication - Apathy, depression, irritability, delusions or agitation - Later: loss of independence, incontinence, swallowing problems ## Red flags - Rapid decline over weeks or months (consider other causes) - Young onset - Early gait disturbance, urinary incontinence or focal neurological signs - Sudden confusion (delirium) - Head injury or anticoagulant use (consider subdural haematoma) ## Diagnosis **Clinical** History from patient and informant, cognitive screening tools (e.g. Mini-Mental State Examination, Montreal Cognitive Assessment) and neuropsychological testing; evidence of decline from a previous level that interferes with daily life. **Tests** Screening for reversible contributors: vitamin B12, thyroid function, blood count, electrolytes, glucose, [kidney](https://durgical.com/en/anatomy/kidney/) and [liver](https://durgical.com/en/anatomy/liver/) function; syphilis and HIV serology where indicated. Cerebrospinal fluid or blood amyloid and tau biomarkers in specialised settings. **Imaging** Brain CT or MRI to exclude other causes (tumour, stroke, subdural haematoma, hydrocephalus) and show medial temporal (hippocampal) atrophy. PET imaging in selected cases. ## Differential diagnosis - Vascular dementia - Dementia with Lewy bodies - Frontotemporal dementia - Depression (pseudodementia) and delirium - Hypothyroidism or vitamin B12 deficiency - Normal pressure hydrocephalus and chronic subdural haematoma ## Goal of treatment Maintain function, independence and quality of life for as long as possible, manage behavioural symptoms and support caregivers. ## Treatment **Medical** Acetylcholinesterase inhibitors for mild to moderate disease; an NMDA receptor antagonist for moderate to severe disease. Benefits are modest. **Medical** Anti-amyloid monoclonal antibodies are approved in some countries for early disease with confirmed amyloid; their use and availability vary and they require MRI monitoring. **Conservative** Non-drug management of behavioural symptoms first; cognitive stimulation and structured routines. **Lifestyle** Control of vascular risk factors, physical and social activity, hearing correction. **Follow-up** Caregiver education and support, advance care planning and periodic review of safety (driving, finances, medication). ## Drugs for this condition - [Donepezil](https://durgical.com/en/pharmacology/donepezil/) - [Rivastigmine](https://durgical.com/en/pharmacology/rivastigmine/) - [Galantamine](https://durgical.com/en/pharmacology/galantamine/) - [Memantine](https://durgical.com/en/pharmacology/memantine/) ## Complications - Falls and fractures - Aspiration pneumonia and malnutrition - Delirium with acute illness - Pressure ulcers in late stages - Caregiver burden and burnout ## Prognosis Progressive and irreversible. Survival after diagnosis is often several years to about a decade, varying with age and health; death is often from infections such as pneumonia. ## Prevention - Control of blood pressure, diabetes and weight - Physical activity and not smoking - Education and social and mental engagement - Treating hearing loss and depression ## Test yourself Think of the answer, then tap the question to see it. ## Which brain structure is affected early in Alzheimer disease, explaining memory loss? The hippocampus and entorhinal cortex in the medial temporal lobe. ## What are the two hallmark lesions of Alzheimer disease? Extracellular amyloid-beta plaques and intracellular neurofibrillary tangles of tau. ## What is the strongest genetic risk factor for late-onset Alzheimer disease? The APOE ε4 allele. ## Which reversible causes are screened for when evaluating dementia? Hypothyroidism, vitamin B12 deficiency, depression, drug effects, subdural haematoma and normal pressure hydrocephalus, among others. ## Which drug class is first line for mild to moderate Alzheimer dementia? Acetylcholinesterase inhibitors. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/alzheimer-disease/) ## Related conditions - [Parkinson disease](https://durgical.com/en/conditions/parkinson-disease/) - [Hydrocephalus](https://durgical.com/en/conditions/hydrocephalus/) - [Hypothyroidism](https://durgical.com/en/conditions/hypothyroidism/) - [Ischaemic stroke](https://durgical.com/en/conditions/ischaemic-stroke/) - [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/) - [Type 2 diabetes mellitus](https://durgical.com/en/conditions/type-2-diabetes-mellitus/) - [Subdural haematoma](https://durgical.com/en/conditions/subdural-haematoma/) - [Presbycusis (age-related hearing loss)](https://durgical.com/en/conditions/presbycusis/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Alzheimer Disease](https://www.ncbi.nlm.nih.gov/books/NBK499922/) (StatPearls (NCBI Bookshelf), 2024). 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