Module 00 — Study Overview

Physical Fitness & Dementia:
A UK Biobank Investigation

This study investigates how grip strength, cardiorespiratory fitness, and lung function relate to incident dementia in a large prospective cohort from the UK Biobank.

Study Design

Prospective cohort study. Participants followed from baseline to first dementia diagnosis, death, or end of follow-up (mean ~12 years).

Population

51,517 participants aged 37–73 at baseline. 628 incident dementia cases. Complete physical fitness measurements required.

Exposures

Grip Strength (mean kg), Cardiorespiratory Fitness (max workload, W), Lung Function (FEV₁, L).

Outcomes

All-cause dementia, Alzheimer’s disease, vascular dementia, other dementia (ICD-10 coded).

Statistical Methods

Cox proportional hazards (Models 1–3), Elastic Net prediction, causal mediation (regmedint), restricted cubic splines.

Proteomic Analysis

2,918 Olink NPX proteins. Multivariable linear regression + Elastic Net selection. GO enrichment for pathway characterization.

Model Specification

Fully Adjusted Model 3

All primary analyses adjust for the following covariates.

Baseline Sociodemographic
  • Age
  • Sex
  • Ethnicity
  • Educational attainment
  • Household income
  • Townsend deprivation index
Lifestyle Variables
  • Smoking status
  • Alcohol consumption
  • Physical activity level
  • Sleep duration
Clinical Covariates
  • Body mass index
  • Hypertension
  • Type 2 diabetes
  • Hyperlipidæmia
  • Cardiovascular disease
  • Anxiety
  • Depression
Analytical Pipeline

Three-Step Mechanistic Analysis

Step 1
Exposure → Protein

Multivariable linear regression of each fitness measure against 2,918 Olink proteins. FDR correction (Benjamini–Hochberg).

Step 2
Protein Selection

Elastic Net Cox regression across fitness-associated proteins to identify the most predictive protein signatures for dementia.

Step 3
Protein → Dementia

Cox models linking selected proteins to dementia risk, with GO enrichment analysis to characterize biological pathways.