Household Size and Neurological Disease Incidence: An Ecological Study
A study analyzed country- and territory-level data from up to 204 settings, finding a strong inverse association between household size and incidence rates of Alzheimer's disease and other dementias (Pearson r=-.841, p<.001). Similar trends for Parkinson's and motor neuron diseases were also observed, revealing a complex relationship with demographic and socioeconomic factors.
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- Human efficacy
- Not established from this source
- Mechanism
- Not reported
- Evidence strength
- Not graded
- Outcome
- Not reported
Why it matters
These findings suggest that larger household sizes may be linked to lower rates of certain neurological diseases, potentially guiding future public health discussions. However, the associations do not prove that household size directly causes changes in disease incidence.
What this does not prove
Limitations include the ecological nature of the findings, meaning they cannot be used to infer individual-level causation. The observed associations are influenced by broader demographic and socioeconomic contexts.
Next milestone
No next milestone was established from the available source.
Study facts
- Study design
- Not reported
- Participants / samples
- Not reported
- Randomised
- Not reported
- Controlled
- Not reported
- Primary endpoint met
- Not reported
- Relevant MS type
- Not reported
- Publication date
- 2026-10-27
- Evidence reviewed
- Abstract only
- Regulatory approval
- Not reported
- Research areas
- Not classified
- Biological target
- Not reported
- Pathway
- Not reported
- Population
- Not reported
- Size of effect
- Not reported
- Secondary endpoints
- Parkinson's disease; motor neuron disease; multiple sclerosis; idiopathic epilepsy; headache disorders; total neurological disorders
- MRI endpoints
- Not reported
- Biomarkers
- Not reported
- Safety
- Not reported
Original sources
Supporting passages (7)
sample size basisMETHODS: Country- and territory-level data from up to 204 settings were analysed.
publication datePublication date: 2026-10-27
primary endpointAverage household size was the primary exposure, and model-derived, age-standardised incidence-rate estimates for Alzheimer's disease and other dementias were the primary outcome.
limitationsThese findings should be interpreted as ecological associations rather than evidence of individual-level causation and suggest that household structure is embedded within broader demograph-ic, socioeconomic, and ageing-related processes.
secondary endpointsPar-kinson's disease, motor neuron disease, multiple sclerosis, idiopathic epilepsy, headache dis-orders, and total neurological disorders were examined as comparative secondary outcomes.
findingsRESULTS: Household size was strongly and inversely associated with Alzheimer's disease and other dementias incidence estimates (Pearson r=-.841, p<.001). The association remained after adjustment for the included covariates (β=-.569, p<.001). Significant inverse adjusted associations were also observed for Parkinson's disease, motor neuron disease, and total neurological disorders, whereas patterns differed for other neurological outcomes. Principal component analysis identified a single ageing-development dimension explaining 72.1% of the variance, with household size loading inversely against life expectancy at age 60, econom-ic affluence, urban living, and the Henneberg Index.
peer reviewedPublication types: Journal Article
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