Male Hair Loss After 40 (Monte Carlo)
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Monte Carlo estimator of hair-density decline and chance of significant hair loss in men after 40 (genetics, hormones, lifestyle, treatment).
NOTEUse & limits
Simplified, assumption-driven Monte Carlo model for what-if exploration only (not diagnosis/medical advice). Results depend heavily on the chosen distributions and threshold.
NOTEHow to customize
Change age_end and significant_density_threshold. Adjust treatment_use p and the distributions to match your scenario. You can also widen/narrow baseline_density_40 std to reflect uncertainty.
VARIABLEgenetic_risk
beta(2.2, 2.2)
Family-history / polygenic risk proxy (higher = more risk).
genetic_risk
VARIABLEandrogen_sensitivity
beta(2.5, 2)
Scalp follicle sensitivity to androgens/DHT (higher = more sensitivity).
androgen_sensitivity
VARIABLEbaseline_density_40
normal(85, 10)
Estimated hair density at age 40 before modeling decline (clamped later).
baseline_density_40
VARIABLElifestyle_score
normal(0, 0.5)
Lifestyle/stress/nutrition proxy; negative worsens, positive improves (clamped later).
lifestyle_score
VARIABLEtreatment_use
bernoulli(0.2)
Uses an evidence-based treatment plan consistently (simple proxy).
treatment_use
VARIABLEtreatment_effect
beta(2, 3)
Fractional reduction in loss rate if treatment_use=1 (higher = better response).
treatment_effect
CONSTANTage_start
40
Model start age.
age_start
CONSTANTage_end
60
Model end age (edit to project to a different age).
age_end
CONSTANTsignificant_density_threshold
60
Below this density we label as 'significant hair loss' in the model.
significant_density_threshold
CONSTANTmax_treatment_reduction
0.7
Caps how much treatment can reduce annual loss rate.
max_treatment_reduction
FORMULAprob_significant_percent
100 * significant_hairloss_flag
Percent indicator (0 or 100) for averaging across sims.
significant_hairloss_flag
prob_significant_percent
FORMULAeffective_loss_rate_percent
100 * effective_annual_loss_rate
Effective annual loss rate expressed as percent per year.
effective_annual_loss_rate
effective_loss_rate_percent
FORMULAyears
age_end - age_start
Projection horizon.
age_end
age_start
years
FORMULAbaseline_density_40_clamped
min(100, max(30, baseline_density_40))
Clamp baseline density to a plausible range.
baseline_density_40
baseline_density_40_clamped
FORMULAlifestyle_score_clamped
min(1, max(-1, lifestyle_score))
Clamp lifestyle score to [-1,1].
lifestyle_score
lifestyle_score_clamped
FORMULArisk_score
0.5*genetic_risk + 0.4*androgen_sensitivity + 0.1*(lifestyle_score_clamped+1)/2
Weighted risk score (0-1-ish).
genetic_risk
androgen_sensitivity
lifestyle_score_clamped
risk_score
FORMULAannual_loss_rate
0.005 + 0.03*risk_score
Base annual density loss rate (0.5% to ~3.5% per year).
risk_score
annual_loss_rate
FORMULAeffective_annual_loss_rate
annual_loss_rate * (1 - treatment_use * max_treatment_reduction * treatment_effect)
Annual loss rate after treatment effect.
annual_loss_rate
treatment_use
max_treatment_reduction
treatment_effect
effective_annual_loss_rate
FORMULAdensity_end
baseline_density_40_clamped * exp(-effective_annual_loss_rate * years)
Projected hair density at age_end (exponential decay).
baseline_density_40_clamped
effective_annual_loss_rate
years
density_end
FORMULAdensity_loss
baseline_density_40_clamped - density_end
Absolute density points lost over the horizon.
baseline_density_40_clamped
density_end
density_loss
FORMULAsignificant_hairloss_flag
density_end < significant_density_threshold ? 1 : 0
1 if projected density falls below threshold; else 0.
density_end
significant_density_threshold
significant_hairloss_flag
OUTPUTProbability of significant hair loss by age_end
Probability of significant hair loss by age_end
Probability that density falls below the threshold by age_end.
OUTPUTEffective annual loss rate
Effective annual loss rate
Annual % density loss rate after treatment adjustment.
OUTPUTProjected density at age_end
Projected density at age_end
Hair density (%) at the end age.
OUTPUTExpected density points lost
Expected density points lost
Expected drop in density from age_start to age_end.
What is Carlo?
Carlo is a visual tool for Monte Carlo simulation. Model uncertainty by dragging probability distributions, connecting them visually, and running thousands of scenarios instantly.