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INTERIM REPORT ON THE OUTCOME OF COGNITIVE ASSESSMENT IN STUDY 7009

Longitudinal cognition follow-up and serial DNA/RNA/SERUM/PLASMA/URINE with or without CSF banking in normal subjects aged 60 to 75 years

Sponsor:                                                         PRECISIONMED, INC

132 North Acacia Avenue

Solana Beach, California 92075

 

Report Prepared by:                                       Catherine Deeprose and Keith Wesnes

                                                                        Cognitive Drug Research Ltd,

CDR House, Gatehampton Road,

                                                                        Goring-on-Thames, RG8 0EN, UK

                                                                        Tel: +44 1491 878700

                                                                        Fax: +44 1491 878701

 

Report Status:                                                 Interim 3

 

Date:                                                              October 2007

 


Contents

1............. summary. 3

1.1.......... DATA COLLECTED.. 3

1.2.......... BASELINE CHARACTERISTICS.. 3

1.3.......... TEST-RETEST RELIABILITY. 4

1.3.1....... Test-retest and change analyses. 4

1.4.......... INDIVIDUAL DECLINE / IMPAIRMENT. 5

2............. DISCUSSION.. 6

3............. REFERENCES.. 6

 


1.                        summary

1.1                    DATA COLLECTED

For the third interim report CDR data are reported for 73 subjects at Visit 1 (baseline mean age 66.6, SD 5.71), for 52 subjects at Visit 2 (first follow-up mean age 66.8, SD 6.01), and for 8 subjects at Visit 3 (second follow-up mean age 68.5, SD 5.88). Age data were only available for 72 subjects at Visit 1, as age was not available for subject 7090068 who had data at baseline only.

1.2                    BASELINE CHARACTERISTICS

The mean baseline performance indicated that the healthy elderly subjects recruited into the present study had similar performance levels compared to CDR normative data for the same age range, with performance within one standard deviation of control data.

Table 1                Baseline Characteristics

 

Visit 1

Range 58 to 83

Mean 66.6 (5.71)

Normative data

Range 58 to 83

Mean 67.6 (5.67)

 

 

N

Mean (SD)

N

Mean (SD)

Power of Attention (msec)

73

1252

(148.0)

1176

1197

(127)

Continuity of Attention (#)

73

91.6

(2.90)

1177

89.7

(4.82)

Quality of Working Memory (SI)

73

1.72

(0.229)

620

1.56

(0.386)

Quality of Episodic Secondary Memory (SI)

73

2.43

(0.323)

N/A

N/A

Speed of Memory (msec)

73

4984

(906.3)

N/A

N/A

Paired Associates Learning Easy Pairs Accuracy

73

92.1

(12.41)

N/A

N/A

Paired Associates Learning Hard Pairs Accuracy

73

86.64

(16.18)

N/A

N/A

 

 

Data taken from Visit 1 performance in the present study and the CDR database v3.0.

 

1.3                    TEST-RETEST RELIABILITY

Test-retest reliability was generally good (>0.5 at Visit 2 and >0.7 at Visit 3) for the five composite scores with the exception of Continuity of Attention, though this is likely due to a restricted data range. Greatest test-retest reliability was seen for Power of Attention, with the Spearman correlation coefficient >0.8 from Visit 1 to Visit 2 and >0.7 from Visit 2 to Visit 3 indicating high levels of test-retest reliability.

 

1.3.1                Test-retest and change analyses

Table 2                Analysis Summary

 

Visit 2

Visit 1 to 2

 

Visit 3

Visit 2 to 3

 

Composite Score

Mean (SD)

Spearman correlation coefficient

Change from Visit 1

Mean (SD)

Spearman correlation coefficient

Change from Visit 1

Power of Attention (msec)

1245

(146.6)

0.824

(P<0.001)

1.69

(86.5)

1229

(83.3)

0.786

(P=0.021)

54.9

(72.8)

Continuity of Attention (#)

90.5

(4.14)

0.39

(P=0.004)

-0.75

(3.31)

93.1

(0.99)

-0.097

(P=0.819)

1.87

(1.13)

Quality Working Memory (#)

1.76

(0.244)

0.60

(P<0.001)

0.06

(0.192)

1.76

(0.200)

0.74

(P=0.366)

0.07

(0.205)

Quality of Episodic Secondary Memory (#)

2.40

(0.293)

0.52

(P<0.001)

-0.04

(0.292)

2.60

(0.235)

0.88

(P=0.004)

-0.01

(0.104)

Speed of Memory (msec)

4632

(776.7)

0.64

(P<0.001)

-266

(778.7)

4519

(694.9)

0.69

(P=0.058)

-47

(547.1)

Paired Associates Learning Easy Pairs Accuracy

99.0

(4.86)

0.12

(P=0.415)

5.29

(11.44)

100

(*)

*

3.13

(8.84)

Paired Associates Learning Hard Pairs Accuracy

85.1

(9.96)

0.054

(P=0.704)

-1.44

(25.44)

100

(*)

*

12.5

(18.90)

** Not estimatable – all values identical.

 

1.4                    INDIVIDUAL DECLINE / IMPAIRMENT

Individual data were examined for performance 1.5 or more standard deviations poorer than age-matched normative data.

For Power of Attention, six subjects showed performance 1.5 standard deviations poorer than age-matched norms:

  • subject 18 at visit 1 (1497 msecs) and visit 2 (1593 millisecs)
  • subject 21 at visit 1 (1513 msecs) and visit 2 (1571 msecs)
  • subject 25 at visit 1 (1580 msecs) and visit 2 (1584 msecs)
  • subject 28 at visit 1 (1540 msecs) and visit 2 (1532 msecs)
  • subject 32 at visit 1 (1556 msecs) and visit 2 (1657 msecs)
  • subject 33 at visit 1 (1383 msecs) and visit 2 (1375 msecs)

 

For Continuity of Attention, one subject showed performance 1.5 standard deviations poorer than age-matched norms:

  • subject 36 at visit 2 (81)

 

For Quality of Working Memory, two subjects showed performance 1.5 standard deviations poorer than age-matched norms:

  • subject 4 at visit 2 (0.87)
  • subject 83 at visit 2 (0.90)

 

 

 

 

2.                         DISCUSSION

Comparison to healthy aged matched controls at the baseline visit show a study population with mean data which is comparable to CDR normative data i.e. performance was within one standard deviation of the controls.

Data for the individual subjects showed that for Power of Attention, approximately 12% of subjects were 1.5 standard deviations or more poorer than normative control data at both Visit 1 and Visit 2. This was consistent with the concept of mild cognitive impairment (MCI) as defined by Petersen (2004) although slightly lower than the cited US study of prevalence rates, which showed 22% of subjects to meet MCI criteria.

In conclusion, the data showed a population with cognitive performance comparable to existing normative data. Some of these subjects may be beginning to show decline or mild impairment.

3.                         REFERENCES

Petersen RC (2004). Mild cognitive impairment as a diagnostic entity. Journal of Internal Medicine; 256: 183-194.

 




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