A majority of individuals diagnosed with Parkinson's disease experience constipation years or decades prior to the onset of motor symptoms

Overview Debates Related claims Topics

The gut-first hypothesis of Parkinson's disease proposes that alpha-synuclein aggregation initiates in enteric neurons and migrates to the brain via connecting nerve bundles

James Parkinson described gastrointestinal dysfunction in his 1817 work An Essay on the Shaking Palsy

Transplanting fecal microbiota from individuals with Parkinson's disease into germ-free mice induced motor impairments and neuroinflammation not observed with healthy control microbiota

Alpha-synuclein is a neuronal protein that forms pathological intracellular aggregates capable of causing nerve cell death in Parkinson's disease

Parkinson's disease causes irreversible neuronal death in brain regions including the substantia nigra pars compacta

Selegiline, also known as Deprenyl, is an MAO inhibitor originally approved as a prescription drug for Parkinson's disease

A pooled analysis of over 160,000 adults showed that walking 7,000 steps daily correlated with 28% fewer physical falls and a 38% lower risk of dementia

The APOE2 allele is associated with a reduced risk of Alzheimer's disease but an elevated risk of cardiometabolic conditions

Approximately 60% of individuals diagnosed with dementia have comorbid cardiometabolic conditions

Blood-based biomarkers used to evaluate dementia pathology include the amyloid-beta 42/40 ratio, phosphorylated tau 217, neurofilament light chain, and glial fibrillary acidic protein

Limbic-predominant age-related TDP-43 encephalopathy (LATE) produces a distinct pattern of dementia that damages frontal brain regions before affecting memory structures

Approximately 25% of individuals carry one copy of the APOE4 allele, and approximately 6% carry two copies

East African populations carry a genetic variant near the APOE gene that neutralizes the Alzheimer's disease risk associated with the APOE4 allele

Approximately 2% of Alzheimer's disease cases are caused by deterministic mutations in genes such as presenilin and amyloid precursor protein

Post-mortem autopsies of individuals diagnosed with dementia reveal non-amyloid pathologies, including Lewy bodies composed of alpha-synuclein and TDP-43 protein inclusions

Carrying two copies of the APOE4 allele increases the risk of developing Alzheimer's disease by 9 to 10 times

Carrying a single copy of the APOE4 allele triples an individual's risk of developing Alzheimer's disease

Tissue loss in Alzheimer's disease typically begins in the memory system, spreads to language systems, and eventually affects frontal brain regions involved in planning and decision-making

Approximately 5% of 70-year-olds are diagnosed with Alzheimer's disease

After 70 years of age, the incidence of Alzheimer's disease doubles every five years