Methodologic factors which contribute to variations in experimental pain threshold reported for older people.

Using the same study groups and psychophysical methods, we have tested the hypothesis that variations in pain threshold with advancing age are best explained by variations in stimulus duration. Fifteen young adults and 15 older people without clinical evidence of neurologic disease or psychologic dysfunction had pain thresholds determined with heat and electrical stimuli using the method of limits; for electrical stimulation a double random staircase design was used. The stimulus duration was 1-100 s for heat and 50-5000 ms for electrical stimulation. It was found that older people have an increased threshold for thermal and electrically induced pain if the stimulus duration is kept short. This result explains much of the variability in age associated pain threshold in the literature.

Considerations in the assessment and management of older people with chronic pain.

INTRODUCTION: The aim of the paper is to describe the philosophical underpinnings and methodologies in the management of chronic pain in older people. METHODS: The paper represents a summary of the data concerning the management of pain in older people. These data have been gleaned from various sources, including textbooks, reviews, original papers and conference reports. RESULTS: Persistent pain affects approximately 50% of the older population above 65 years. Chronic pain describes a syndrome of persistent pain and accompanying adverse psychosocial consequences and functional disabilities. This is believed to be an inaccurate appraisal of the nociceptive stimulus by the patient. Assessment is based on a multidisciplinary cognitive-behavioural model. Management consisting of a seamless blend of pharmacological, physical and psychological therapies is likely to yield the best results. CONCLUSION: Chronic pain in older people is an emerging problem in the specialty of geriatric medicine. The traditional multidisciplinary approach is likely to give good results.

Development of a pain attitudes questionnaire to assess stoicism and cautiousness for possible age differences.

This study aimed to develop a pain attitudes questionnaire (PAQ) and examine its reliability and validity for use in assessing the constructs of stoicism and cautiousness relevant to pain perception. The questionnaire was administered to 373 healthy community-dwelling individuals who were subsequently divided into four age groups to test for differences in stoicism and cautiousness, two attitudes that have previously been claimed to influence pain perception and report among older adults. Factor analysis revealed that two dimensions of stoicism and two dimensions of cautiousness are measured by the scale, with reticence and superiority characterizing the first construct and self-doubt and reluctance characterizing the second. There was support for the scale's reliability and validity. Age-related increase in degree of reticence to pain, self-doubt, and reluctance to label a sensation as painful was found, emphasizing the need for careful consideration of pain attitudes in older patients who may underreport their pain symptoms.

The epidemiology of pain in elderly people.

Acute pain probably occurs at much the same rate across all age groups. On the other hand, self-report of chronic pain seems to increase up to, but not beyond, the seventh decade of life. Chronic pain in older people is more often experienced in major joints, the back, legs and feet, whereas visceral pain and headache are reported less often. There is a divergence between an increasing load of pain-associated disease and a plateau of chronic pain complaint in old age that probably reflects impairment in the nociceptive function of the nervous system. However, the contribution of social, behavioral, cognitive, and affective dimensions of the pain experience to this divergence between disease and pain have not been fully evaluated. Most of the answers to these and other questions require longitudinal studies with pain as the predominant focus of attention rather than addressing the symptom of pain as an ancillary measure relevant to other aspects of aging.

Age-related differences in pain perception and report.

The clinical and laboratory-based evidence for age-related differences in pain perception and report are reviewed. Most clinical studies suggest a relative decrease in the frequency and intensity of pain symptoms associated with myocardial complaints, visceral infections, musculoskeletal conditions, and postoperative and malignant pain problems in adults of advanced age. The findings from experimentally controlled laboratory investigations are more equivocal and vary according to the type and intensity of noxious stimulation. Nonetheless, such studies also provide some additional support for the notion of an age-related decrease in pain perception and report. Evidence has not determined whether the observed changes are caused by the aging process or reflect other age-associated effects, including an increased presence of comorbid disease, biocultural cohort effects, or altered psychosocial influences.

Quantitative electroencephalographic changes induced by odor detection and identification tasks: age related effects.

There are no previous studies which have compared quantitative electroencephalographic (QEEG) activity in young adult and normal elderly participants during olfactory tasks. This may be important if QEEG is to have a role in distinguishing between normal and pathological aging associated with this sensory system. Seventeen healthy elderly subjects (mean age 79.00+/-3.54 years) and 16 young adult controls (mean age 22.60+/-2.00 years) participated in the study. As reported in previous studies, beta1 and 2 activity was significantly greater in elderly subjects compared to young adults, thus confirming the reliability and validity of this study's quantitative electroencephalographic (QEEG) methodology. More alpha activity was evident in young adults compared with the elderly, whilst θ activity was distributed differently in the two age groups. These findings support previous literature suggesting EEG bandwidth activity reflect greater attentional capacity in young adults and EEG desynchronization in older people. Elderly subjects who identified two or fewer odors were found to have more beta activity in the olfaction condition compared to resting eyes closed, which may reflect cognitive impairment. These findings stress the importance of distinguishing subgroups of healthy elderly adults when examining the electroencephalographic profile.

Chronic pain management in older people.

Successful management of chronic pain in older people is dependent on a careful history and physical examination as it is in young adults. However, detailed attention must also be paid to the effects of co-morbidity on the pain and its treatment, on communication strategies with patients who often have sight and hearing impediments, and on the feasible range of functional outcomes for each patient. Drug interactions are common in older people as they take more medications and have reduced ability to clear most analgesic and adjuvant medications. This suggests a larger than usual role for non-pharmacological management strategies. However, simple analgesics and narcotics are safe to use in older people without overt liver and renal disease, providing the lowest dose compatible with functional improvement is sought; the goal of therapy is to maintain optimum function rather than cure the pain. In general the outcome is positive for both the patient and the practitioner as patients usually respond to medical, physical, psychosocial and cognitive behavioural programmes as well as young adults if given an appropriate milieu, adequate time and empathy.

An examination of pain perception and cerebral event-related potentials following carbon dioxide laser stimulation in patients with Alzheimer's disease and age-matched control volunteers.

BACKGROUND: Pain perception is known to depend on integrated cognitive processing. Alzheimer's disease affects 5% to 10% of older adults, but the impact of this disease on pain sensitivity and report has yet to be fully investigated. AIM OF INVESTIGATION: The present study examined pain threshold, the reliability of pain report and the central nervous system processing of noxious input, as indexed by cerebral event-related potentials (CERP). METHODS: Carbon dioxide laser detection and heat pain thresholds were determined on the hand dorsum of 15 healthy older adults (Mini-Mental State Examination [MMSE] score 29.9 +/- 0.3) and 15 persons with cognitive impairment (MMSE score 12.7 +/- 6.1). Using an array of 15 silver/silver chloride scalp electrodes, the CERP and subjective rating of stimulus intensity were recorded after fixed intensity, 25 W laser stimuli. RESULTS: Compared with age-matched controls, the detection threshold for just noticeable sensation was significantly increased in elderly adults suffering from Alzheimer's disease. There was no difference in pain threshold intensity between persons with cognitive impairment and controls, although the former group was less reliable in reporting detection and pain threshold sensations. The subjective rating of a 25 W stimulus was virtually identical in both groups, and the amplitude of the major CERP component (P400) was similar; however, cognitively impaired adults exhibited a significant increase in the latency of the P400 response. CONCLUSIONS: The present findings indicate that pain perception in response to an acute heat pain stimulus is not diminished in older persons with cognitive impairment. Patients with Alzheimer's disease may be slightly less reliable in threshold pain report, although the subjective rating of evoked pain and the level of poststimulus cortical activation following noxious stimulation were found to be similar to those of controls. A longer latency of the CERP may suggest slower cortical processing of nociceptive input by persons with Alzheimer's disease.

Age-related differences in the time course of capsaicin-induced hyperalgesia.

The effect of age on hyperalgesia, one of the most common signs of injury, has not been previously examined in humans. A psychophysical study was conducted in 10 young (26.9+/-4.6 years) and 10 older (79. 0+/-5.7 years) healthy volunteers to investigate the effect of age on the development of hyperalgesia induced by topical application of capsaicin (0.1 ml, 5 mg/ml). The capsaicin patch (diameter 2 cm) was applied for 1 h. The intensity of capsaicin-induced spontaneous sensation, mechanical pain threshold, area of flare, heat and punctate hyperalgesia were measured hourly for 3 h after the application. Older adults took a longer period to report first pain. There was no age effect on the magnitude of spontaneous sensation, flare size and area of heat hyperalgesia. The area of heat hyperalgesia rapidly decreased over time in both age groups. In marked contrast, the area of punctate hyperalgesia and associated reduction in the mechanical pain threshold were maintained in older adults over the entire 3 h test period, but resolved rapidly in young adults. We conclude that, given the same intensity of noxious stimulation, older adults display a similar magnitude of hyperalgesia as younger persons. However, once initiated, punctate hyperalgesia appears to resolve more slowly in older people. This finding may indicate age differences in the plasticity of spinal cord neurons following an acute injury.

A community-based program that provides free choice of intervention for older people with chronic pain.

This study sought to evaluate the efficacy of a community-based intervention program that provides free choice of intervention for improving outcomes for community-dwelling older people with chronic nonmalignant pain. A quasiexperimental before and after nonequivalent group design was used. The treated group was composed of 71 participants, and the untreated group was composed of 40 individuals. A 6-month follow-up measurement was included to determine the long-term effects of the program. The findings of the program showed significant benefits for those who completed the program compared with those who did not participate. Evaluation of the program suggested that an initial educational seminar had a positive impact that empowered the participants to make more informed choices regarding interventions for managing pain. Significant reduction in pain intensity and improved level of physical activity were reported by the participants at completion of the interventions. However, results of a 6-month follow-up showed that only the benefits for physical activity were maintained. The findings show that the present program improved the short-term outcomes for older people with chronic pain and has potential as a clinical option for accessible and low-cost pain management for older people with chronic pain.

Increased movement pain in osteoarthritis of the hands is associated with A beta-mediated cutaneous mechanical sensitivity.

The relationship between joint pain and hyperalgesia has been explored in animal models of articular inflammation, but is yet to be shown in the most common rheumatologic condition: osteoarthritis. In this study, cutaneous thermal and mechanical pain thresholds were measured over the thumb of patients with osteoarthritis of the hands. In symptomatic patients, pain was manipulated through resisted active movement of the thumb. Provocation of movement pain (MP) was associated with a sustained fall in mechanical pain thresholds. Thermal pain thresholds remained stable during increases in joint pain. Increased mechanical sensitivity after exacerbation of MP was alleviated by A beta fiber blockade. It appears that superficial tenderness over the osteoarthritic thumb fluctuates with pain arising from movement of the joint. It is concluded that dorsal horn mechanisms contribute to MP-related hyperalgesia in osteoarthritis of the hands.

Factors associated with analgesic and psychotropic medications use by community-dwelling older people with chronic pain.

OBJECTIVE: The present study sought to examine use prevalence and factors associated with use of analgesic and psychotropic medications in community-dwelling older people with chronic non-malignant pain. METHOD: The study group comprised 193 community-dwelling older people with daily chronic non-malignant pain who were selected from a random sample of 1,000 older people in Melbourne. RESULTS: The use prevalence for the study group was 63% for analgesics and 39% for psychotropic medications, which is higher than the general older population without chronic pain (p < 0.00001). More women with chronic pain used analgesics, while psycho-social factors such as problems with sleeping and living at home alone were found to be associated with an increased use of psychotropic medications. CONCLUSION: A high proportion of community-dwelling older people with chronic non-malignant pain use analgesic and psychotropic medications. IMPLICATIONS: These findings provide the basis for further investigation into the level and appropriateness of analgesic and psychotropic medication use by older people with chronic pain.

Effects of diabetes on creatine kinase activity in streptozotocin-diabetic rats.

OBJECTIVE: To study the effect of diabetes on the creatine kinase (CK) activity in different tissues of streptozotocin-induced diabetic rats. METHODS: Serum samples, heart, extensor digitorum longus, brain and bladder were collected from both streptozotocin-induced diabetic rat and control group. Ck was measured by enzymologic method. RESULTS: The body weight, heart weight and brain weight were reduced significantly compared with control group (P < 0.001), but bladder weight was increased significantly (P < 0.001). CK activity in serum and extensor digitorum longus in diabetic rat was significantly lower (P < 0.001); CK activity in diabetic heart was lower (P < 0.01); and in brain also lower (P < 0.05). A higher CK activity in diabetic bladder was found (P < 0.001). CONCLUSIONS: Diabetes can result in a lower CK activity in serum, heart, brain and extensor digitorum longus that may affect the energy metabolism in the tissues. A higher CK activity in diabetic bladder may reflect a functional compensatory mechanism.

Age-related changes in qEEG during cognitive tasks.

Early diagnosis of dementia can be difficult. Quantitative EEG (qEEG) in combination with cognitive tasks shows promise for improving diagnostic accuracy. The study of task induced qEEG changes in normal ageing is a prerequisite for differentiating these changes from those which are specific to dementia. Sixteen young adults (mean age 28.8+/-5.6 years) and 16 healthy cognitively normal older subjects (mean age 73.4+/-7.9 years) participated in the study. EEG recordings were made while subjects were in a relaxed (or resting) state, and also while they performed arithmetic and language tasks. From the resting to the arithmetic conditions, there was decreased alpha activity and increased delta and beta-3 activity for both subject groups. Changes in alpha and delta activity were found in almost all sites and could be associated with arousal. Increase in beta-3 activity was focal, appearing only in the posterior region of the brain and it could be assumed that this area is highly involved in arithmetic processes. In the young adult group, theta activity increased from the resting to the arithmetic conditions, while in the older group theta activity changes were in the opposite direction. From the resting to the language condition, there was increased delta activity and decreased alpha and beta-1 activity for both subject groups. Changes in alpha and delta activity were again found in almost all sites. The decrease in beta-1 activity was found in only four sites, but these were not specific to a region of the brain known to be involved in language processing. This consistency in qEEG changes during cognitive tasks suggests that the method can be applied to the investigation of cognitive deficits associated with a number of neurological syndromes.

Age-related changes in sympathetic modulation of sensory nerve activity in rat skin.

OBJECTIVES: Sensory nerves play an important role in mediating neurogenic inflammation and subsequent tissue healing. A decrease in sensory nerve function with increasing age has been reported to correlate with poor tissue healing. Sympathetic nerves are known to modulate sensory nerve function, and changes in this modulation could also have important implications with ageing. The aims of this study were to examine the effect of different frequency electrical stimulation (ES) on the microvascular responses obtained to sensory nerve activation in young, aged and capsaicin-pretreated rats and modulation of these responses by sympathetic efferents. METHODS: Using laser Doppler flowmetry, vascular responses to antidromic ES of the sciatic nerve were monitored in the base of vacuum-induced blisters in the hind footpad. The non-selective alpha-adrenoceptor antagonist phentolamine (3 mg/kg, i.v.) was administered 20 min prior to ES. RESULTS: At high frequency ES (20V, 2ms, 15Hz for 1 min), the vascular response in old rats was significantly reduced (46 percent decrease, p < 0.05) compared to young control. At low frequency ES (20 V, 2 ms, 5 Hz for 1 min) however, older rats produced similar vascular responses to the young. Capsaicin-pretreated rats showed significantly reduced vascular responses to both high and low frequency ES, regardless of age. Pretreatment with phentolamine significantly increased the microvascular response in young rats at high (87 percent) and low (36 percent) frequency ES. In contrast, phentolamine significantly increased the ES-induced response in old rats at high frequency only (147 percent increase). CONCLUSIONS: The results suggest that the aged sensory nerve responds preferentially to low frequency ES and that sympathetic efferents exert an inhibitory modulatory effect on the vascular response evoked by sensory nerve stimulation. There are age-related changes in sympathetic modulation of sensory nerve-mediated responses which is dependent on stimulation frequency.

Quantitative electroencephalography, with serial subtraction and odour detection in the differentiation of Alzheimer's disease and vascular dementia.

The diagnosis of dementia can be difficult, yet diagnostic accuracy has important prognostic and therapeutic implications. Nevertheless, conventional electroencephalography (EEG) has always played a secondary role in dementia investigation. More recently quantitative EEG (qEEG) has allowed more detailed and objective analysis of EEG data, but there is still no clearly defined clinical role for qEEG. We have used relative power qEEG measures made during resting and active brain conditions (serial subtraction and odour detection tasks) to differentiate between demented and non-demented subjects, and between subjects with different forms of dementia. Electroencephalograms were obtained from 15 subjects with clinically diagnosed Alzheimer's disease (AD), 16 with a clinical diagnosis of vascular dementia (VaD), and 16 non-demented control subjects. Discriminate function analyses were used to differentiate groups according to task, electrode site, and frequency bandwidth. Correct classification, as demented or non-demented, was made for 93% of cases using qEEG comparisons of resting states with eyes closed and eyes opened. Almost all subjects with AD and VaD were correctly classified with qEEG recorded during odour detection (95%). qEEG for serial subtraction correctly classified AD and VaD in 91% of the dementia group. These results have important implications for future qEEG research, and may be pertinent to the precision of diagnosis in patients with dementia.

Sympathetic modulation of sensory nerve activity with age: human and rodent skin models.

1. Sensory nerves serve an afferent role and mediate neurogenic components of inflammation and tissue repair via an axon reflex release of sensory peptides at sites of injury. Dysfunction of these nerves with age could contribute to delayed tissue healing. 2. Complementary animal and human skin models were used in the present studies to investigate changes in the modulation of sensory nerve function by sympathetic efferents during ageing. Laser Doppler flowmetry was used to monitor neurogenic skin vascular responses. 3. The animal model used skin of the hind footpad of anaesthetized rats combined with electrical stimulation of the sciatic nerve, while the human model comprised capsaicin electrophoresis to the volar surface of the forearm. Sympathetic modulation was effected by systemic phentolamine pretreatment in animals and local application in the human model. 4. The results obtained from the human model confirmed the reported decline in sensory nerve function and showed no change in sympathetic modulation with age. The results from the animal model confirm and expand results obtained from the human model. 5. The use of low (5 Hz) and high (15 Hz) frequency electrical stimulation (20 V, 2 ms for 1 min) revealed a preferential response of aged sensory nerves to low-frequency electrical stimulation parameters with differential sympathetic modulation that is dependent on the frequency of stimulation.

Validation of an automated up-timer for measurement of mobility in older adults.

OBJECTIVE: To test the reliability, validity and utility of an "up-timer", an automated device to measure time spent standing and walking. DESIGN: Repeat measurement of mobility one week apart in a convenience sample. SETTING: Hostel and nursing homes in Melbourne. PARTICIPANTS: 26 hostel and 24 nursing home residents (aged 70-99 years) participated. They were mobile, with or without the use of walking aids or personal assistance. OUTCOME MEASURES: "Up-time" (measured with the up-timer); functional activity (measured with the Barthel Index, Functional Independence Measure, Timed Up & Go, and Human Activity Profile); and disability (measured by the Rapid Disability Rating Scale). RESULTS: The test-retest reliability of the up-timer was high (Pearson's r = 0.84; P < 0.001). Pearson's correlation between the up-timer results and results of functional and disability measures ranged from r = 0.47 to r = 0.55. The functional measures correlated more highly among themselves (r = 0.79 to r = 0.92). The performance-based Timed Up & Go test had moderate levels of correlation with both the up-timer and the functional measures. Use of the device was well accepted by both participants and staff. CONCLUSIONS: The up-timer is a practical, objective and reliable means of measuring mobility. The useful information it provides is different from, but overlaps with, that obtained from subjective observation or self report. It will complement existing subjective and performance-based measures of activity and mobility.

The classification of patients with chronic pain: age as a contributing factor.

OBJECTIVE: To explore the influence of age on the empirical classification of patients with chronic pain. DESIGN: Cluster analyses of two cohorts defined by age. SETTING: Two outpatient pain management clinics for young and older people. SAMPLE: The sample consisted of 340 patients between the ages of 17 and 93 years, who were consecutively assessed on admission to the multidisciplinary pain clinics. The subjects were allocated to two groups according to age; either 17 to 65 years or 66 years and older. MEASUREMENTS: Clustering was carried out using standardised scores from measures of pain (McGill Pain Questionnaire), depression (Zung or Geriatric Depression Scales), and impact of pain (Sickness Impact Profile adapted for pain). RESULTS: Previous classifications of younger adults were replicated in the clusters of: "Good Pain Control," "Positive Adaption to Pain," and "Chronic Pain Syndrome." A fourth cluster, "High Impact," was identified in the older group and subsequently replicated in the combined sample. This group consisted of subjects with high levels of impact of pain and depression and low levels of pain. CONCLUSION: Age differences are present in the clinical presentation of chronic pain patients. Some older patients with chronic pain present with a unique constellation of clinical symptoms, and the classic patient profile of high pain, high impact, and high mood disturbance (i.e., Chronic Pain Syndrome) identified in younger to middle-aged adults does not occur as frequently in older patients. A number of explanations are presented to account for these differences, including comorbidity as well as other medical, psychological, and social factors.