MAPT and dementia: In the same CamPaIGN cohort at 5 years from diagnosis, all but one of the PD cases who had developed dementia carried the H1/H1 genotype (18/65 of H1/H1 versus 1/34 of H2 carriers), with an estimated odds ratio (with adjustment for age and other confounding factors) for dementia of 12.1 (57), strikingly greater than the estimated odds ratio for PD susceptibility for MAPT of 1.4 (53), suggesting that MAPT H1 has a much more profound influence on cognitive function in early PD than on risk of disease per se.