Diurnal cycle of salivary cortisol in older adult men and women with subjective complaints of memory deficits and/or depressive symptoms: Relation to cognitive functioning

Figures & data

Figure 1 Percentage representation of the three diurnal cortisol subgroups in the present study (elderly with memory problems/depressed mood) and that found by Smyth et al. (1997; healthy young population) and Ice et al. (2004; healthy elderly). Chi-square analysis for independence found overall significant relationship between study and subgroup representation (p = 0.001).

Figure 2 Mean ( ± SEM) cortisol levels (nonlog, μg/dl) across the four sampling periods for (a) day 1, (b) day 2, and (c) overall (i.e. day 1 and 2 combined) mean cortisol levels across sampling periods. Significant differences were found between the typical and flat cortisol subgroups for mean bedtime cortisol levels (p = 0.02). Trend was found between typical and inconsistent subgroups (p = 0.08). *,.

Table I.  Means (SEM) score on demographic variables as a function of diurnal cortisol subgroup.

Demographics	Flat	Typical	Inconsistent
N	29	5	8
Gender (female:male)	20:9	5:0	7:1
Age	68.53 (1.33)	69.00 (2.77)	67.38 (3.41)
Education	13.93 (0.49)	13.60 (2.02)	15.00 (1.22)
I.Q.	105.71 (3.51)	109.20 (5.79)	106.63 (3.99)
MMSE	28.00 (0.41)	28.20 (0.58)	28.89 (0.52)
PSQ	51.40 (2.03)	45.28 (3.99)	55.03 (3.57)
GDS	11.17 (1.20)	9.60 (2.91)	14.00 (1.59)
MAC-Q*	28.48 (.61)	28.20 (0.92)	24.38 (0.98)
Morning cortisol	1.49 (0.15)	1.55 (0.29)	1.67 (0.27)
Afternoon cortisol	0.97 (0.07)	0.74 (0.16)	1.38 (0.26)
Evening cortisol^†	1.21 (0.13)	0.51 (0.13)	1.48 (0.50)

Note: gender column shows ratio of females to males (f:m). Displayed cortisol levels are non-transformed in units μg/dl

* Significant difference between inconsistent subgroup and flat (p = 0.01)

^† Significant difference between flat and typical subgroup (p = 0.01).

Table II.  Means (SEM) score on neurocognitive tests as a function of diurnal cortisol subgroup.

Cognitive test	Flat (mean : SEM)	Typical (mean : SEM)	Inconsistent (mean : SEM)
Digit span	6.07 (0.21)	6.00 (0.37)	6.30 (0.45)
Declarative memory
Immediate recall related pairs	8.28 (0.57)	9.8 (1.32)	8.75 (0.88)
Immediate recall non-related pairs	4.00 (0.71)	7.00 (2.49)	3.38 (1.29)
Delay recall related pairs	9.86 (0.59)	11.2 (0.80)	10.00 (1.05)
Delay recall non-related pairs	6.79 (0.79)	7.2 (2.58)	6.75 (1.39)
Verbal fluency
Phonetic	11.13 (0.79)	18.20 (2.11)	13.28 (1.17)
Category	15.97 (1.18)	19.80 (2.27)	19.50 (1.34)

Figure 3 Mean ( ± SEM) score on phonetic/semantic subtests of the verbal fluency task as a function of diurnal cortisol subgroup. The flat subgroup preformed significantly more poorly than the typical subgroup (*p = 0.02) by recalling fewer phonetic words within a one-minute time span.

Table III.  Relationship between cortisol subgroup representation and subjective complaints.

	Flat (%)	Typical (%)	Inconsistent (%)
Memory	55.2*	60	12.5
Depression	3.4	0*	50*
Memory–depression	41.4*	40	37.5

* Significant differences found (p < 0.05).

Smyth JM, Ockenfels MC, Gorin AA, Catley D, Porter LS, Kirschbaum C, Hellhammer DH, Stone AA. Individual differences in the diurnal cycle of cortisol. Psychoneuroendocrinology 1997; 22: 89–105

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Ice GH, Katz-Stein A, Himes J, Kane RL. Diurnal cycles of salivary cortisol in older adults. Psychoneuroendocrinology 2004; 29: 355–370

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