Key characteristics of studies relating to PTH levels, parathyroid conditions, cognitive function and dementia.

MMSE: Mini Mental State Examination; CDR: Clinical Dementia Rating scale; MMS: Mini Mental State, NR: Not reported; CKD: chronic kidney disease.a:Study reporting results for more than one type of research design (i.e. prospective/pre-post and cross-sectional or case-control) but basic characteristics are the same, therefore only prospective designs are included here.b: No control group.c: mean age of six groups.d: studies included participants undergoing dialysis.e:unclear whether calcium /vitamin D is treated as a potential covariate or one of the predictors in linear regression models.Key characteristics of studies relating to PTH levels, parathyroid conditions, cognitive function and dementia.