Table 1.

Rates of Conversion to MCI and Dementia

	General population	Parkinson’s disease	Essential tremor
Annual rate of conversion from normal cognition to MCI	5.1% (95% CI = 4.6% - 5.6%) [52] 5.6% (95% CI = 4.6 - 5.6%) [54] 5% (95% CI = 3 - 6%) [53]	9.9% [55] 7.2% [57] 12.1% [56]	25.0% [58]* 3.1% [13]*
Annual rate of conversion from MCI to dementia	2.6% (95% CI = 2.3 – 2.9%) [59] 4.0% [61] 6.3% [60]	10.6% [62] 7.6% [56] 8.9% [55] 15.5% [63]	12.5% [58]
Conversion to dementia if followed for long enough (i.e., cumulative prevalence) or prevalence of dementia in oldest old	22.7% among persons aged 90 – 105 [64] 35.2% in 95 year-olds [65]	78.2% over 8 years [66] 83% over 20 years [67]	No Data

^*Only two studies have been conducted, both with major methodological limitations

MCI = Mild Cognitive Impairment. CI = Confidence Interval.