Mukaila A. Raji

Hand grip strength and incident ADL disability in elderly Mexican Americans over a seven-year period

Background and aims: Little is known about muscle strength as a predictor of disability among older Mexican Americans. The aim of this study was to examine the association between hand grip strength and 7-year incidence of ADL disability in older Mexican American men and women. Methods: A 7-year prospective cohort study of 2493 non-institutionalized Mexican American men and women aged 65 or older residing in five south-western states. Maximal hand grip strength test, body mass index, cognitive function, activities of daily living, self-reports of medical conditions (arthritis, diabetes, heart attack, stroke, cancer, hip fracture), and depressive symptoms were obtained. Results: In a Cox proportional regression analysis, there was a linear relationship between hand grip strength at baseline and risk of incident ADL disability over a 7-year follow-up. Among non-disabled men at baseline, the hazard ratio of any new ADL limitation was 1.90(95% CI 1.14–3.17) for those in the lowest quartile, when compared with men in the highest hand grip strength quartile, after controlling for age, marital status, medical conditions, high depressive symptoms, MMSE score, and BMI at baseline. Among non-disabled women at baseline, the hazard ratio of any new ADL limitation was 2.28 (95% CI 1.59–3.27) for those in the lowest quartile, when compared with women in the highest hand grip strength quartile. Conclusions: Hand grip strength is an independent predictor of ADL disability among older Mexican American men and women. The hand grip strength test is an easy, reliable, valid, inexpensive method of screening to identify older adults at risk of disability.

The Basis for Diminished Functional Recovery after Delayed Peripheral Nerve Repair

The postsurgical period during which neurons remain without target connections (chronic axotomy) and distal nerve stumps and target muscles are denervated (chronic denervation) deleteriously affects functional recovery. An autologous nerve graft and cross-suture paradigm in Sprague Dawley rats was used to systematically and independently control time of motoneuron axotomy, denervation of distal nerve sheaths, and muscle denervation to determine relative contributions of each factor to recovery failure. Tibial (TIB) nerve was cross-sutured to common peroneal (CP) nerve via a contralateral 15 mm nerve autograft to reinnervate the tibialis anterior (TA) muscle immediately or after prolonging TIB axotomy, CP autograft denervation, or TA muscle denervation. Numbers of motoneurons that reinnervated TA muscle declined exponentially from 99±15 to asymptotic mean (±SE) values of 35 ± 1, 41 ± 10, and 13 ± 5, respectively. Enlarged reinnervated motor units fully compensated for reduced motoneuron numbers after prolonged axotomy and autograft denervation, but the maximal threefold enlargement did not compensate for the severe loss of regenerating nerves through chronically denervated nerve stumps and for failure of reinnervated muscle fibers to recover from denervation atrophy. Muscle force, weight, and cross-sectional area declined. Our results demonstrate that chronic denervation of the distal stump plays a key role in reduced nerve regeneration, but the denervated muscle is also a contributing factor. That chronic Schwann cell denervation within the nerve autograft reduced regeneration less than after the denervation of both CP nerve stump and TA muscle, argues that chronic muscle denervation negatively impacts nerve regeneration.

Relationship Between Frailty and Cognitive Decline in Older Mexican Americans

OBJECTIVES: To examine the association between frailty status and change in cognitive function over time in older Mexican Americans.

Frailty in Older Mexican Americans

Objectives: To identify sociodemographic characteristics and health performance variables associated with frailty in older Mexican Americans.

Risk of Myocardial Infarction in Older Men Receiving Testosterone Therapy

Background: Testosterone therapy for older men has increased substantially over the past decade. Research on the effects of testosterone therapy on cardiovascular outcomes has yielded inconsistent results. Objective: To examine the risk of myocardial infarction (MI) in a population-based cohort of older men receiving intramuscular testosterone. Method: Using a 5% national sample of Medicare beneficiaries, we identified 6355 patients treated with at least 1 injection of testosterone between January 1, 1997, and December 31, 2005. We matched this cohort to 19 065 testosterone nonusers at a 1:3 ratio based on a composite MI prognostic score. Patients were followed until December 31, 2005, or until they lost coverage from Medicare, enrolled in a health maintenance organization, experienced a MI, or died. Result: In a Cox regression analysis adjusting for demographic and clinical characteristics, receipt of testosterone therapy was not associated with an increased risk of MI (hazard ratio [HR] = 0.84; 95% CI = 0.69-1.02). In this analysis, there was an interaction between receipt of testosterone and quartile of risk of MI (P = 0.023). For men in the highest quartile of the MI prognostic score, testosterone therapy was associated with a reduced risk of MI (HR = 0.69; 95% CI = 0.53-0.92), whereas there was no difference in risk for the first (HR = 1.20; 95% CI = 0.88-1.67), second (HR = 0.94; 95% CI = 0.69-1.30), and third quartiles (HR = 0.78; 95% CI = 0.59-1.01). Conclusion: Older men who were treated with intramuscular testosterone did not appear to have an increased risk of MI. For men with high MI risk, testosterone use was modestly protective against MI.

Cognitive status, muscle strength, and subsequent disability in older Mexican Americans

Objectives: To examine the association between Mini‐Mental State Examination (MMSE) score and subsequent muscle strength (measured using handgrip strength) and to test the hypothesis that muscle strength will mediate any association between impaired cognition and incident activity of daily living (ADL) disability over a 7‐year period in elderly Mexican Americans who were initially not disabled.

Mexican Americans and Frailty: Findings From the Hispanic Established Populations Epidemiologic Studies of the Elderly

OBJECTIVES We examined the prevalence of frailty among Mexican American older adults and explored the correlates associated with becoming frail to determine their affect on disability and morbidity in this population. METHODS We studied the trajectory of frailty over 10 years in 2049 Mexican Americans participating in the Hispanic Established Populations Epidemiologic Studies of the Elderly. We constructed a frailty index based on weight loss, exhaustion, grip strength, walking speed, and physical activity and collected data on sociodemographic and health status, comorbidities, and functional measures of performance. RESULTS The sample was 58% female, with a mean age of 74.43 years (SD = 6.04) at baseline. Fifty-five percent of participants at baseline and 75% of the surviving sample at follow-up (n = 777) were classified as prefrail or frail. Of persons identified as frail at baseline, 84% died by the end of follow-up. Baseline age, diabetes, arthritis, smoking status, body mass index, cognition, negative affect, and number of comorbid conditions were predictors of frailty at follow-up (R(2) = 0.29; P < .05). CONCLUSIONS Further research into ways to reduce the number of Mexican American older adults who become frail and disabled and therefore lose their independence is needed. Future studies should continue to examine the trajectory of frailty as a dynamic process that includes psychosocial and cognitive components.

Cognitive Status and Future Risk of Frailty in Older Mexican Americans

BACKGROUND Because cognitive impairment and frailty share common risk factors (eg, high proinflammatory cytokines), we examined whether poor cognition predicts subsequent risk of frailty in initially nonfrail Mexican Americans aged 67 years and older. METHODS Frailty was defined as meeting one or more of the following components: (a) unintentional weight loss of >10 pounds, (b) weakness, (c) self-reported exhaustion, and (d) slow walking speed. Sociodemographic factors, Mini-Mental State Examination, medical conditions (stroke, heart attack, diabetes, arthritis, cancer, and hypertension), and depressive symptoms were obtained. Main outcome measure was risk of becoming frail over 10 years. RESULTS Out of 942 participants who were nonfrail at baseline (1995-1996), 57.8% were women and the mean age was 73.7 years (SD = 5.3). In general estimation equation models testing the relationship between Mini-Mental State Examination (<21 vs. ≥21) and the risk of becoming frail over a 10-year period, there was a significant association (odds ratio = 1.09, 95% confidence interval = 1.00-1.19; p = .0310)] between the cognition-by-time interaction and odds of becoming prefrail or frail over time. This association was independent of age, sex, marital status, education, time, and medical conditions, indicating that nonfrail participants with poor cognition had a 9% odds per year of becoming frail over time compared with those with good cognition. CONCLUSION Low Mini-Mental State Examination score was independently associated with increased risk of frailty over a 10-year period in older Mexican Americans. Low Mini-Mental State Examination score may be an early marker for future risk of frailty.

Near vision impairment predicts cognitive decline: data from the Hispanic Established Populations for Epidemiologic Studies of the Elderly.

Objectives: To estimate the association between sensory impairment and cognitive decline in older Mexican Americans.

Effect of a dementia diagnosis on survival of older patients after a diagnosis of breast, colon, or prostate cancer: implications for cancer care.

BACKGROUND Preexisting dementia affects cancer care. Knowledge of how dementia affects survival after a cancer diagnosis may help guide cancer care decisions. We therefore examined the associations between preexisting diagnoses of dementia and survival from breast, colon, and prostate cancer. METHODS We conducted a retrospective cohort study of 106,061 patients aged 68 years or older diagnosed as having breast, colon, or prostate cancer, using data from the linked Surveillance, Epidemiology and End Results-Medicare database. We assessed the risks of mortality from cancer and noncancer causes, stratified by presence or absence of preexisting dementia diagnoses. Cox proportional hazards regression was used to adjust for confounding variables. RESULTS Seven percent of our sample had preexisting dementia diagnoses. Survival after a cancer diagnosis was markedly worse in demented than in nondemented patients. Most of the excess deaths came from noncancer causes; 33.3% of those with a dementia diagnosis died within 6 months of a cancer diagnosis, compared with 8.5% of patients without dementia. Less than 17.0% of the excess mortality in patients with dementia who had breast or colon cancer was explained by a more advanced cancer stage at diagnosis. None of the excess deaths in prostate cancer was explained by stage at diagnosis. For all 3 cancers, the presence of preexisting dementia diagnoses attenuated the relationship between stage at diagnosis and survival. CONCLUSIONS Preexisting dementia diagnoses were associated with high mortality, mostly from noncancer causes. The effect of cancer stage at diagnosis on mortality was significantly reduced in older patients with precancer diagnoses of dementia.