Alzheimer's disease (AD)

Alzheimer's disease often begins due to certain gene mutations, ongoing inflammation, and prolonged unhealthy lifestyle choices, including lack of physical activity and a diet high in sugar.
Lardelli et al. 2024 J Alzheimers Dis 99: S367-S381

Alzheimer's Disease (AD) is the most common neurodegenerative disorder, characterized by the extracellular deposition of amyloid-beta (Aβ) and intracellular accumulation of hyperphosphorylated aggregated tau. It is a chronic, age-related progressive neurological disorder accounting for approximately 80% of dementia cases globally.
Bisogno et al. 2021 Life 11: 934
Onyango et al. 2021 Biomedicines 9: 524
Chen & Holtzman 2022 Immunity 55: 2236-2254

Alzheimer's disease (AD) cases are rising globally, doubling every 20 years, with neurological pathologies developing over more than 20 years before symptoms appear.
Abdelhamid et al. 2022 Nutrients 14(12): 2543

Alzheimer’s disease (AD) is incurable. It affects the brain and worsens life quality in older adults. AD has several features, including amyloid plaques, neurofibrillary tangles, neuronal loss, and gliosis.
Sharma et al. 2021b

Chronic stress plays a role in Alzheimer's disease (AD). It affects the body at many levels and impacts Alzheimer's disease (AD) progression. It alters gut-brain communication, which involves signaling mechanisms. This changes gut microbiota, its composition, and its activities.
Sharma et al. 2021b

Epidemiology

• An estimated 6.2 million people in the US are currently living with AD, and this number is expected to grow to 13.8 million by 2060. Between 2000 and 2019, deaths from AD have increased by 145%.

  
  

  Alzheimers Dement. 17(3): 327-406 (2021)

  
  



• Ten percent of individuals over 65 years have AD, and its prevalence continues to rise with increasing age.

  
  

  Onyango et al. 2021 Biomedicines 9: 524

  
  

Clinical Hallmarks

The main clinical hallmarks of Alzheimer's disease (AD), such as beta-amyloid plaques and neurofibrillary tangles, begin during the preclinical stage when cognitive deficits are not yet apparent.

Bisogno et al. 2021 Life 11: 934

Risk Factors

1. Diet: Diet is considered the single most significant factor influencing the gut microbiota

   
   

   Frausto et al. 2021 Front. Neurosci. 15:736814

   
   



2. Saturated Fat and Sugars: An excess of saturated fat and simple sugars in the diet is a known environmental risk factor for Alzheimer's disease (AD)

   
   

   Więckowska-Gacek et al. 2021 Ageing Research Reviews 70: 101397

   
   

Symptoms and Impact

• Agitation: Common in patients with Alzheimer's disease (AD)

  
  

  Ward & Citrome 2022 Expert Opinion on Investigational Drugs 31(8): 773-780

  
  



• Disability and Dependence: Dementia, particularly Alzheimer's disease (AD), is the primary cause of disability and dependence in elderly persons, leading to a significant negative socioeconomic impact.

  
  

  El-Hayek et al. 2019 Alzheimers Dis. 70: 323-41

  
  

Diagnosis

The biomarker framework for clinical diagnosis includes:

• Beta-amyloid 42 level


• Total tau and phosphorylated tau (p-Tau) levels in cerebrospinal fluid (CSF)


• Positron emission tomography (PET) amyloid imaging


• Fluorodeoxyglucose uptake on PET


• Structural magnetic resonance imaging (MRI)

  
  

  Jack Jr et al. 2011 Arch Neurol 68: 1526-35
  Jack et al. 2016a Neurology 87: 539-47

  
  

see also:
Alzheimer's Disease (AD) & Amyloid Pathology
Alzheimer's Disease (AD) & Tau Protein
Alzheimer’s Disease (AD) & Neuroinflammation
Alzheimer's Disease (AD) & Pathogenicity
Cognitive impairment