Table 3.

Decisional Capacity Performances for Cognitively Normal Older Controls (NCs) and Participants with Mild Cognitive Impairment (MCI)

Decisional Capacity Ability (Range)	Description	Variable	NC n=40	MCI n = 40	P-Value
			Mean ± Standard Deviation
Understanding (0–26)	Assesses understanding of the nature of the study and procedures, such as the study’s purpose, methodology (e.g., double-blind, placebo- controlled), and risks and benefits	Understanding total	24.2 ± 1.7	21.3 ± 3.2	.001*
		1. Nature of research project	7.8 ± 0.6	6.6 ± 1.5	<.001†
		2. Understanding study purpose	1.7 ± 0.5	1.5 ± 0.6	.14†
		3. Effects on individualized care	5.7 ± 0.5	5.1 ± 1.1	.004†
		4. Risks and benefits of participating	7.0 ± 1.1	6.2 ± 1.4	.003†
Appreciation (0–6)	Measures recognition of the effects that participating (or not participating) will have on the participant’s care and well-being	Appreciation total	5.6 ± 0.6	5.0 ± 1.2	.02*
		1. No personal medical benefit	1.7 ± 0.6	1.4 ± 0.7	.07†
		2. Possibility of reduced benefit	2.0 ± 0.0	1.8 ± 0.5	.04†
		3. Withdrawal possible	1.9 ± 0.3	1.7 ± 0.5	.08†
Reasoning (0–8)	Assesses the participant’s comparative analysis regarding the study’s benefits and risks	Reasoning total	6.4 ± 1.2	5.7 ± 1.3	.002*
		1. Consequential reasoning	1.8 ± 0.4	1.7 ± 0.5	.08†
		2. Comparative reasoning	1.2 ± 0.7	0.9 ± 0.6	.05†
		3. Generating consequences	1.5 ± 0.7	1.3 ± 0.7	.22†
		4. Logical consistency of choice	2.0 ± 0.2	1.9 ± 0.3	.65†
Expression of choice (0–2)	Participant’s ability to express their decision	Expression of Choice total	2.0 ± 0.2	1.9 ± 0.3	NA‡
Total score			38.1 ± 2.7	33.8 ± 5.1	.008*

^*Between-group comparisons for all MacArthur Competence Assessment Tool for Clinical Research dimensions reflect analysis of covariance results, adjusting for Wide Range Achievement Test-3 Reading.

^†Between-group item analyses are based on unadjusted Mann-Whitney comparisons.

^‡No statistical analyses were conducted on the ‘Expression of Choice dimension because of restriction of range.