Effects of Testosterone Supplementation on Separate Cognitive Domains in Cognitively Healthy Older Men: A Meta-analysis of Current Randomized Clinical Trials.

Background: An increasing body of literature suggests a positive, neuroprotective effect for testosterone on cognition in older men. However, randomized clinical trials (RCTs) examining the effects of testosterone supplementation (TS) on cognitive function have been inconclusive.

Objective: To investigate the potential for TS to prevent cognitive decline in otherwise cognitively healthy older men, by examining the differential effects of TS on cognitively healthy older men in RCTs.

Multiple Mechanisms Linking Type 2 Diabetes and Alzheimer's Disease: Testosterone as a Modifier.

Evidence in support of links between type-2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) has increased considerably in recent years. AD pathological hallmarks include the accumulation of extracellular amyloid-β (Aβ) and intracellular hyperphosphorylated tau in the brain, which are hypothesized to promote inflammation, oxidative stress, and neuronal loss. T2DM exhibits many AD pathological features, including reduced brain insulin uptake, lipid dysregulation, inflammation, oxidative stress, and depression; T2DM has also been shown to increase AD risk, and with increasing age, the prevalence of both conditions increases.

Cerebral amyloid-β accumulation and deposition following traumatic brain injury--A narrative review and meta-analysis of animal studies.

Traumatic brain injury (TBI) increases the risk of neurodegenerative disorders many years post-injury. However, molecular mechanisms underlying the relationship between TBI and neurodegenerative diseases, such as Alzheimer's disease (AD), remain to be elucidated. Nevertheless, previous studies have demonstrated a link between TBI and increased amyloid-β (Aβ), a protein involved in AD pathogenesis.

The Effects of Testosterone Supplementation on Cognitive Functioning in Older Men.

Reduction in testosterone levels in men during aging is associated with cognitive decline and risk of dementia. Animal studies have shown benefits for testosterone supplementation in improving cognition and reducing Alzheimer's disease pathology. In a randomized, placebo-controlled, crossover study of men with subjective memory complaint and low testosterone levels, we investigated whether testosterone treatment significantly improved performance on various measures of cognitive functioning.

Evolution of testosterone treatment over 25 years: symptom responses, endocrine profiles and cardiovascular changes.

Introduction: Testosterone treatment has evolved rapidly over the past 25 years as new, more effective and convenient methods have become available. This study reports experience with seven different methods, introduced on the market in the UK.

Aim: To establish the symptom response when testosterone treatment was initiated on the basis of clinical features and symptoms of androgen deficiency, and the resulting endocrine, biochemical and physiological responses.

Testosterone replacement therapy in older male subjective memory complainers: double-blind randomized crossover placebo-controlled clinical trial of physiological assessment and safety.

Testosterone replacement therapy (TRT) has been investigated in older men as a preventative treatment against Alzheimer's disease and dementia. However, previous studies have been contradictory. We assessed TRT physiological effects in 44 older men (aged 61 ± 7.

Testosterone deficiency syndrome: cellular and molecular mechanism of action.

There is virtually no correlation between what are generally accepted to be the symptoms of deficient androgen in men and levels of androgens as measured in the laboratory. Now that androgen deficiency is being shown to play a part in conditions as diverse as metabolic syndrome, diabetes, and coronary heart disease, a hypothesis is needed to explain this apparent discrepancy between measured androgen levels and our understanding of the symptoms of androgen deficiency. When the possible mechanisms for androgen actions are considered, one explanation emerges that androgen may act much like insulin in persons with type 2 diabetes mellitus: the degree of androgen resistance may be variable depending on the organs or systems considered.

Is testosterone treatment good for the prostate? Study of safety during long-term treatment.

Introduction: For men with androgen deficiency on testosterone replacement therapy (TRT), clinical concern relates to the development of prostate cancer (PCa).

Aim: An updated audit of prostate safety from the UK Androgen Study was carried out to analyze the incidence of PCa during long-term TRT.

Main Outcome Measures: Diagnosis of PCa in men receiving TRT, by serum prostate-specific antigen (PSA) testing and digital rectal examination (DRE), and its relation to different testosterone preparations.

International web survey shows high prevalence of symptomatic testosterone deficiency in men.

Introduction: Though the clinical significance of testosterone deficiency is becoming increasingly apparent, its prevalence in the general population remains unrecognised. A large web-based survey was undertaken over 3 years to study the scale of this missed diagnosis.

Methods: An online questionnaire giving the symptoms characterising testosterone deficiency syndrome (Aging Male Symptoms-AMS-scale) was set up on three web sites, together with questions about possible contributory factors.

Time for international action on treating testosterone deficiency syndrome.

Aim: Testosterone deficiency is having an increasing impact on men's health because of global aging, higher levels of obesity, diabetes and metabolic syndrome and adverse environmental factors such as stress xenoestrogens and anti-androgens. The question addressed is to what extent the large body of evidence on the benefits and safety of testosterone therapy is applied in clinical practice.

Methods: Demographic data for men over the age of 50 from different regions of the world have been compared with the number of men in that age group estimated from sales figures to be receiving testosterone treatment.

Distinct effects of testosterone on plasma and cerebrospinal fluid amyloid-beta levels.

The effect of testosterone on the levels of the Alzheimer's disease amyloid-beta peptide (Abeta) was investigated in guinea pigs. Castrated guinea pigs (GPX) were administered testosterone at two different dosages, following which plasma and cerebrospinal fluid (CSF) Abeta_{40} levels were measured. Plasma Abeta_{40} levels were reduced in GPX in the early stages of low-dose testosterone treatment, whereas CSF Abeta_{40} levels were only reduced by the time circulating testosterone had returned to untreated GPX levels.

The paradox dividing testosterone deficiency symptoms and androgen assays: a closer look at the cellular and molecular mechanisms of androgen action.

Introduction: Central to the diagnosis and treatment of testosterone deficiency syndrome in the adult male is the remarkable paradox that there is a very poor correlation between the characteristic symptoms and levels of serum androgens.

Aim: Because androgen deficiency can be associated with severe symptomatology, as well as diverse conditions such as coronary heart disease, diabetes, and metabolic syndrome, the aim was to present an evidence-based working hypothesis to resolve this confusing clinical paradox.

Methods: A review of the possible mechanisms in testosterone deficiency syndrome was carried out, and a hypothesis to explain this paradox and associated problems in the diagnosis and clinical management of androgen deficiency was established on the basis of a review of the literature.

The validity of androgen assays.

Unlabelled: Problems in the measurement of androgens and in interpreting results have been reviewed and classified as follows: PREANALYTICAL FACTORS: The exact sampling conditions in relation to circadian and seasonal variations, diet, alcohol, physical activity and posture.

Physiological And Medical Factors: Androgen levels vary according to the patient's general health, stress, sexual activity and smoking habits. Analytical variables.