Table 1.

Demographic and behavioral data.

N=39	Mean (SD)	Range
Age (years)	78.1 (7.8)	62-94
Education (years)	14.7 (3.0)	10-20
Health Composite*	1.3 (1.2)	0-4
MMSE	28.2 (1.9)	24-30
SRT Free Recall	23.8 (10.6)	4-10
Digit Span	11.5 (2.3)	6-15
Digit Symbol	41.3 (12.7)	14-67
Trail Making A	40.2 (15.4)	19-83
Trail Making B	100.7 (42.1)	34-180
Boston Naming Test	55.0 (5.5)	34-60
Ongoing Task RT (s)
Control Block	1722 (453)	994-2976
Focal Block	1737 (407)	1165-2958
Non-focal Block	1951 (670)	1026-3494
Accuracy (%)
Ongoing Task	.95 (.02)	.90-.98
Focal PM	.68 (.47)	0-1.0
Non-focal PM	.29 (.42)	0-1.0

^*Health composite incidence rates: diabetes (5), hypertension (22), stroke (5), heart problems (14), depression (4) and mild head injury (4). Co-morbidity possible.

RT=reaction time in seconds

MMSE=Mini-Mental Status Exam (Folstein et al., 1975)

SRT=Free and Cued Selective Reminding Test (Grober, et al., 1988)

Digit Span = sum of digit span backward and forward (Wechsler, 1987)

Boston Naming Test (Mack et al., 1992)

Digit Symbol and Trail Making A and B (Wechsler, 1987)