Prenatal sex hormone exposure and risk of Alzheimer disease: a pilot study using the 2D:4D digit length ratio.

OBJECTIVE: Our aim was to investigate an association between prenatal sex hormone exposure and dementia diagnosis. BACKGROUND: Some evidence indicates that relatively low testosterone levels are a risk factor for men to develop Alzheimer disease (AD). Most research has examined current rather than premorbid testosterone levels, and little research has addressed testosterone and AD in women. METHODS: In 20 men and women diagnosed with AD and 20 controls, we estimated prenatal exposure to testosterone and estrogen using the ratio of the length of the second to the fourth digit (2D:4D). We analyzed the data using a 2 (men versus women)×2 (controls versus AD participants) analysis of variance. RESULTS: The men with AD had significantly higher 2D:4D ratios than the male controls, indicating lower levels of prenatal testosterone and higher levels of prenatal estrogen exposure. The women with AD had significantly lower 2D:4D ratios than the female controls, indicating higher levels of prenatal testosterone and lower levels of prenatal estrogen exposure. CONCLUSIONS: These findings suggest that lower levels of prenatal testosterone and higher levels of estrogen exposure are a risk factor for AD in men, and that higher levels of prenatal testosterone and lower levels of prenatal estrogen exposure are a risk factor for women. Risk for AD may be related to prenatal exposure to a sex hormone different from an individual's chromosomal sex.

Contralateral stimulation, using TENS, of phantom limb pain: two confirmatory cases.

OBJECTIVES: This study aims to evaluate the effectiveness of trans-electric nerve stimulation (TENS) for phantom limb pain applied to contralateral limb (nonamputated limb). DESIGN: Two detailed single case studies using TENS on the contralateral limb are reported in a longitudinal study with one-year follow-up. Five variables were measured across this period. The study comprised of five sequential stages (Pre-assessment, Preliminary baseline, Start of intervention, Extended assessment, One-year follow-up). SETTING AND PATIENTS: Patients were identified at the Rookwood Hospital in Cardiff. They subsequently received regular home visits. The first patient was a 24-year-old male who had suffered a left below-elbow amputation following a car crash. The second patient was a 38-year-old male who had a transfemoral right amputation further to a viral infection. MEASURES: The following semistructured interview and questionnaires were used: McGill Comprehensive pain questionnaire part A and B; The Cambridge Phantom Limb Profile; The Groningen Questionnaire: Problems after Arm Amputation; and 13 Visual Analog Scales. CONCLUSIONS: Both patients showed a significant improvement in their perception of phantom limb pain and sensations that was maintained at one-year follow-up. A randomized blinded controlled trial to confirm these positive outcomes is required.