In Ireland, alzheimer's Disease is managed by neurologists. Alzheimer's disease is the most common cause of dementia, driven by extracellular beta-amyloid plaques and intracellular hyperphosphorylated tau tangles that destroy neurons in the medial temporal lobe and spread through the cortex over 15-25 years. It accounts for 60-70% of the 55 million people living with dementia worldwide and affects approximately 7 million adults in the United States, with prevalence doubling every five years after age 65.
Alzheimer's disease (ICD-10: G30) is a progressive neurodegenerative disorder defined by two co-existing pathologies: extracellular plaques of misfolded amyloid-beta peptide (primarily Aβ42) and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. These changes begin 15-25 years before symptoms appear, first in the entorhinal cortex and hippocampus, then spreading through the neocortex along a stereotyped Braak staging pattern. Synaptic dysfunction, neuroinflammation driven by reactive microglia, and bulk neuronal loss follow, producing the clinical syndrome of progressive amnestic dementia. The 2024 National Institute on Aging-Alzheimer's Association (NIA-AA) Revised Criteria reclassified Alzheimer's as a biological diagnosis defined by core biomarkers — Aβ42/40 ratio, phosphorylated tau (p-tau181, p-tau217), and downstream neurodegeneration markers — rather than purely clinical syndrome.
The key symptoms of Alzheimer's Disease are: Progressive short-term memory loss — forgetting recent conversations, repeating questions within minutes, misplacing items, and missing appointments — is the earliest and most reliable symptom in 80-90% of typical cases., Word-finding difficulty with hesitations, circumlocutions ('the thing you write with'), and substitutions; reading and reading comprehension decline later than speech production., Executive dysfunction: trouble planning meals, managing finances, following multi-step instructions, and adapting to new situations. Often noticed first by family during travel or financial tasks., Visuospatial impairment producing getting lost in familiar places, difficulty judging distances when driving, and trouble using familiar tools — sometimes mistaken for vision loss., Disorientation to time and place, beginning with date confusion and progressing to inability to identify season, year, or the home address., Loss of insight into the deficit (anosognosia) — patients often deny memory problems even when objective testing is clearly abnormal. Family members are usually a more reliable source of history., Apraxia — difficulty performing learned motor sequences such as dressing, using cutlery, or operating familiar appliances despite preserved motor strength..
Diagnosis follows a stepwise workflow combining clinical assessment, structured cognitive testing, screening laboratory studies, structural brain imaging, and increasingly, fluid and PET biomarkers. The decisive history is taken from both the patient and a knowledgeable informant — the informant usually provides the most accurate picture of functional change. Structured cognitive testing with the Mini-Mental State Examination (MMSE) or Montreal Cognitive Assessment (MoCA) quantifies global cognition; the MoCA is more sensitive for mild cognitive impairment. A standard work-up screens for treatable mimics with TSH, vitamin B12, comprehensive metabolic panel, depression assessment, and brain imaging (MRI preferred over CT) to rule out subdural haematoma, normal-pressure hydrocephalus, vascular disease, and structural lesions. MRI in Alzheimer's typically shows medial temporal lobe atrophy with relatively preserved frontal and motor regions. The 2024 NIA-AA Revised Criteria established Alzheimer's as a biological diagnosis defined by core biomarkers. Cerebrospinal fluid testing for the Aβ42/40 ratio plus phosphorylated tau (p-tau181 or p-tau217) is sensitive and specific; amyloid PET imaging with florbetapir, florbetaben, or flutemetamol can confirm cerebral amyloid in vivo. Tau PET is now used to stage disease. Plasma p-tau217 assays have emerged as a high-accuracy blood test (positive and negative predictive values exceeding 90% in specialist clinics) and are being introduced as a first-line biomarker. Differential diagnosis must exclude vascular dementia, dementia with Lewy bodies, frontotemporal dementia, depression-related pseudodementia, and normal-pressure hydrocephalus — each has distinct features and management implications.
Median survival from clinical diagnosis of Alzheimer's dementia is 8-10 years, with substantial variation depending on age at diagnosis, sex, comorbidities, and disease stage. Patients diagnosed in their late 60s often live 10-15 years; those diagnosed after 80 typically 4-6 years. Progression follows a relatively predictable trajectory: 2-4 years from MCI to mild dementia, 4-7 years through moderate stage, and 1-3 years in severe dementia. Death is most often from pneumonia, urinary tract infection with sepsis, malnutrition, pressure injuries, or pulmonary embolism rather than the dementia itself. Anti-amyloid antibody therapy (lecanemab, donanemab) slows decline by 25-35% over 18-24 months in early disease; longer-term effects are still being characterised. Prognosis is improved by treating coexisting vascular risk factors, depression, sleep apnoea, hearing loss, and pain. Predictors of faster decline include APOE-ε4 homozygosity, higher tau burden on PET, early age at onset, prominent neuropsychiatric symptoms, and significant comorbid vascular disease.
Refer to a neurologist, geriatrician, or memory clinic when cognitive symptoms persist beyond 6 months, atypical features are present (early language or visuospatial decline, age under 65, rapid progression, prominent psychiatric symptoms), when biomarker confirmation is needed before disease-modifying therapy, when imaging suggests alternative diagnoses, or when behavioural symptoms are severe. Primary care can monitor stable, established disease, but specialist input is essential for diagnosis, treatment initiation, and complex symptom management.
Find specialists →Alzheimer's is progressive and not reversible with current therapy, so 'recovery' applies to the timeline of disease control rather than cure. Cholinesterase inhibitors typically deliver their measurable benefit within 3-6 months of titration; about 25-50% of patients show a clear response. Anti-amyloid antibody therapy clears amyloid plaques within 12-18 months in most responders, often allowing donanemab to be stopped once PET is plaque-clear. ARIA, if it occurs, is usually within the first 6 months of therapy and typically resolves over 4-12 weeks after pausing or discontinuing treatment. Functional decline continues despite therapy — at a slowed rate — across all stages.
Aim for 150 minutes per week of moderate aerobic activity (walking, cycling, swimming) plus twice-weekly resistance training and balance work. In moderate dementia, supervised group programmes or chair-based routines are safer. Falls prevention becomes a priority as the disease advances — physiotherapy review for gait, footwear, and home hazards is recommended at least annually.
Look for a behavioural neurologist or geriatrician with memory-clinic experience, access to biomarker testing (CSF, plasma p-tau, amyloid PET), and an established pathway for anti-amyloid antibody therapy where appropriate. Ask whether the practice screens for APOE genotype before disease-modifying therapy and how ARIA surveillance is managed. Continuity matters — Alzheimer's care is a multi-year relationship spanning diagnosis, treatment, behavioural complications, and end-of-life planning.
Medically reviewed by AIHealz Medical Editorial Board · May 12, 2026
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