The effects of testosterone on cognition in elderly men: a review

Anabolic androgenic steroid dependence is associated with executive dysfunction

BACKGROUND

Anabolic androgenic steroid (AAS) dependence is associated with a high prevalence of intra- and interpersonal problems, hence it is central to identify cognitive factors related to the development and maintenance of dependence.

METHODS

The study explores executive functions (EFs) in a sample of 174 male weightlifters, divided into three groups; 1) AAS dependents; n = 58, 2) AAS non-dependents; n = 38 and 3) AAS non-users; n = 78, using a targeted battery of neuropsychological (NP) tests, and self-report questionnaires assessing EFs in everyday life, ADHD symptoms and psychological distress.

RESULTS

Multivariate analysis of variance showed significant between-group differences on several EFs, including working memory [F (2, 169) = 13.79, p < .001, ηp² = 0.14], mental flexibility [F (2, 169) = 4.82, p = .009, ηp² = 0.05], problem-solving [F (2, 169) = 4.77 p = .010, ηp² = 0.05] and inhibition [F (2, 163) = 4.15, p = .017, ηp² = 0.05]. Additionally, significant between-group differences were seen for self-reported problems with EFs [F (2, 124) = 4.38 p = .015, ηp² = 0.07], ADHD symptoms [F (2, 124) = 7.02 p = .001, ηp² = 0.10], and psychological distress [F (2, 124) = 4.11 p = .019, ηp² = 0.06]. Post hoc tests showed that AAS dependents exhibited poorer EFs and reported more psychological distress compared to non-users.

CONCLUSION

AAS dependence is associated with executive dysfunction, which might be related to continued abuse despite adverse side-effects and social consequences. Increased awareness of executive dysfunction could have important implications for treatment and rehabilitation.

The complex association between metabolic syndrome and male hypogonadism

BACKGROUND

The complex association between metabolic syndrome (MetS) and male hypogonadism is well established. A number of observational studies show that low testosterone is associated with insulin resistance and an increased risk for diabetes mellitus and MetS in men.

AIMS

To elucidate the association between MetS and male hypogonadism, present epidemiological data on the co-existence of the two comorbidities, enlighten the underlying pathophysiology and appraise the effects of testosterone supplementation therapy (TTh) and lifestyle modifications on MetS and body composition in men.

MATERIALS AND METHODS

Systematic search to PubMed and Medline databases for publications reporting data on association between MetS and male hypogonadism.

RESULTS

Both MetS and male hypogonadism have a high prevalence in the general population and are frequently co-existing e.g. in males with diabetes. Accumulating evidence from animal and human studies suggests that MetS is involved in the pathogenesis of hypogonadism in males as well as the other way around. On the other hand, there is evidence for a favorable effect of testosterone supplementation in testosterone deficient men with MetS and/or diabetes mellitus.

CONCLUSIONS

Studies with superior methodological characteristics are needed in order to establish a role for testosterone supplementation in men with MetS and/or diabetes mellitus.

Sex- and age-associated differences in episodic-like memory and transcriptional regulation of hippocampal steroidogenic enzymes in rats

The aim of this study was to evaluate the episodic-like memory (ELM) and the transcriptional regulation of the enzymes involved in hippocampal allopregnanolone synthesis in young adult and middle-aged male and female rats. Young adult males, but not middle-aged ones, showed a good performance in the ELM task. In contrast, neither young nor middle-aged females were able to discriminate the spatial order in which the objects were presented. In females, aging decreased the transcription of steroidogenic-related genes. In addition, the mRNA levels of 5α-reductase-1 were higher and the methylation of its promoter was lower in young adult females than in males, suggesting an epigenetic control. Further studies are needed to establish correlations between ELM and the transcriptional regulation of hippocampal steroidogenic enzymes. Our results contribute to the knowledge of sex differences in gene expression, methylation and memory during aging.

Viral-mediated Zif268 expression in the prefrontal cortex protects against gonadectomy-induced working memory, long-term memory, and social interaction deficits in male rats

In humans, some males experience reductions in testosterone levels, as a natural consequence of aging or in the clinical condition termed hypogonadism, which are associated with impaired cognitive performance and mood disorder(s). Some of these behavioral deficits can be reversed by testosterone treatment. Our previous work in rats reported that sex differences in the expression of the transcription factor Zif268, a downstream target of testosterone, within the medial prefrontal cortex (mPFC) mediates sex differences in social interaction. In the present study, we aimed to examine the effects of gonadectomy (GNX) in male rats on mPFC Zif268 expression, mood and cognitive behaviors. We also examined whether reinstitution of Zif268 in GNX rats will correct some of the behavioral deficits observed following GNX. Our results show that GNX induced a downregulation of Zif268 protein in the mPFC, which was concomitant with impaired memory in the y-maze and spontaneous object recognition test, reduced social interaction time, and depression-like behaviors in the forced swim test. Reinstitution of mPFC Zif268, using a novel adeno-associated-viral (AAV) construct, abrogated GNX-induced working memory and long-term memory impairments, and reductions in social interaction time, but not GNX-induced depression-like behaviors. These findings suggest that mPFC Zif268 exerts beneficial effects on memory and social interaction, and could be a potential target for novel treatments for behavioral impairments observed in hypogonadal and aged men with declining levels of gonadal hormones.

Klinefelter syndrome has increased brain responses to auditory stimuli and motor output, but not to visual stimuli or Stroop adaptation

Klinefelter syndrome (47, XXY) (KS) is a genetic syndrome characterized by the presence of an extra X chromosome and low level of testosterone, resulting in a number of neurocognitive abnormalities, yet little is known about brain function. This study investigated the fMRI-BOLD response from KS relative to a group of Controls to basic motor, perceptual, executive and adaptation tasks. Participants (N: KS = 49; Controls = 49) responded to whether the words "GREEN" or "RED" were displayed in green or red (incongruent versus congruent colors). One of the colors was presented three times as often as the other, making it possible to study both congruency and adaptation effects independently. Auditory stimuli saying "GREEN" or "RED" had the same distribution, making it possible to study effects of perceptual modality as well as Frequency effects across modalities. We found that KS had an increased response to motor output in primary motor cortex and an increased response to auditory stimuli in auditory cortices, but no difference in primary visual cortices. KS displayed a diminished response to written visual stimuli in secondary visual regions near the Visual Word Form Area, consistent with the widespread dyslexia in the group. No neural differences were found in inhibitory control (Stroop) or in adaptation to differences in stimulus frequencies. Across groups we found a strong positive correlation between age and BOLD response in the brain's motor network with no difference between groups. No effects of testosterone level or brain volume were found. In sum, the present findings suggest that auditory and motor systems in KS are selectively affected, perhaps as a compensatory strategy, and that this is not a systemic effect as it is not seen in the visual system.

Relationships between testosterone levels and cognition in patients with Alzheimer disease and nondemented elderly men

BACKGROUND/AIMS

Previous research suggests that low levels of testosterone may be associated with the development of Alzheimer disease (AD), as well as poorer performance on certain neuropsychological tests and increased risk of depression.

METHODS

This study utilized data from 61 nondemented older men and 68 men with probable AD.

RESULTS

Testosterone levels did not differ between the groups. Regression analyses in men with AD revealed that testosterone levels did not significantly predict performance on neuropsychological tests or a measure of depression. Among controls, testosterone levels predicted estimated premorbid verbal IQ and performance on a verbal fluency test.

CONCLUSION

Findings suggest that testosterone is not associated with most neuropsychological test performances in patients with AD.

Transdermal testosterone improves verbal learning and memory in postmenopausal women not on oestrogen therapy

OBJECTIVE

The aim of this study was to examine the effects of testosterone on verbal learning and memory in postmenopausal women.

DESIGN

Randomized, placebo-controlled trial in which participants were randomized (1:1) to transdermal testosterone gel 300 mcg/day, or identical placebo, for 26 weeks.

PATIENTS

Ninety-two postmenopausal women aged 55-65 years, on no systemic sex hormone therapy.

MEASUREMENTS

The primary outcome was the score for the International Shopping List Task (ISLT) of CogState. Secondary outcomes included other CogState domains, the Psychological General Well-Being Index (PGWB) and safety variables.

RESULTS

Eighty-nine women, median age 60 years, were included in the primary analysis. Testosterone treatment resulted in statistically significantly better performance for the ISLT (improved verbal learning and memory) compared with placebo, adjusted for age and baseline score (mean difference 1·57; 95%CI 0·13, 3·01) P = 0·03). There were no significant differences for other CogState domains or the PGWB scores. At 26 weeks, the median total testosterone was 1·7 nm (interquartile range (IQR) 1·1, 2·4) in the testosterone group and 0·4 nm (IQR 0·3, 0·5) in the placebo group.

CONCLUSIONS

The small but statistically significant effect of testosterone treatment on verbal learning and memory in postmenopausal women provides the basis for further clinical trials.

Mild cognitive impairment and dementia: the importance of modifiable risk factors

BACKGROUND

Mild cognitive impairment (MCI), a common condition among the elderly, is defined as a deterioration of memory, attention, and cognitive function that exceeds what would be expected for the individual's age and level of education, yet does not interfere significantly with the activities of daily living. MCI may be a precursor of dementia; the rate of transition from MCI to dementia is 10% to 20% per year. The role of somatic diseases and modifiable risk factors in MCI and dementia needs further study.

METHODS

We analyzed pertinent original articles and reviews published 1990 up to December 2010 that were retrieved by a selective search in PubMed and the Cochrane Library.

RESULTS

MCI and dementia are associated with many somatic disorders and modifiable risk factors. MCI has biologically plausible associations with hypertension, diabetes mellitus, and hyperlipidemia, although the interventional trials performed to date have yielded negative results. Recently, chronic renal failure has also been recognized as a risk factor. Insufficient evidence supports a putative benefit on MCI from the substitution of vitamin B12, vitamin D, or testosterone (when these substances are deficient), the treatment of hyperhomocysteinemia or subclinical thyroid dysfunction, or hormone replacement therapy after menopause. Epidemiological data suggest that a Mediterranean diet, physical activity, and moderate alcohol consumption protect against MCI, while cigarette smoking promotes it and should be stopped.

CONCLUSION

Modifiable risk factors for MCI should be sought (at the very latest) in persons who already have MCI, as their optimal treatment may improve these patients' cognitive performance or keep the existing deficits from progressing.

A transdisciplinary perspective of chronic stress in relation to psychopathology throughout life span development

The allostatic load (AL) model represents an interdisciplinary approach to comprehensively conceptualize and quantify chronic stress in relation to pathologies throughout the life cycle. This article first reviews the AL model, followed by interactions among early adversity, genetics, environmental toxins, as well as distinctions among sex, gender, and sex hormones as integral antecedents of AL. We next explore perspectives on severe mental illness, dementia, and caregiving as unique human models of AL that merit future investigations in the field of developmental psychopathology. A complimenting transdisciplinary perspective is applied throughout, whereby we argue that the AL model goes beyond traditional stress–disease theories toward the advancement of person-centered research and practice that promote not only physical health but also mental health.

Metabolic and endocrine factors in mild cognitive impairment

Mild cognitive impairment (MCI) is a heterogeneous condition with cognitive changes between normal aging and dementia. Some forms of MCI are regarded as potential preclinical forms of dementia. The control of treatable somatic risk factors is of great relevance in patients with MCI, particularly as there is insufficient evidence for the efficacy of interventions targeting neurodegenerative processes, as used in manifest dementia. The etiology of MCI is varied including cerebrovascular risk factors and is also associated with metabolic and endocrine factors. Chronic kidney disease is a newly identified and independent risk factor for MCI. Testosterone substitution is useful if a low testosterone level is present but general screening for testosterone deficiency is not yet recommended. A relationship between MCI and vitamin D or subclinical thyroid dysfunction may exist, but the value of substitution is doubtful and requires large randomized placebo-controlled trials. Although an association between vitamin B12 deficiency or hyperhomocysteinemia and MCI is present, substitution of vitamin B12 or folate does not appear to prevent cognitive decline. Estrogen-only hormone replacement therapy may be considered only in younger postmenopausal women, but may have detrimental effects on cognitive function in older postmenopausal women. Other less familiar or unknown risk factors contributing to cognitive dysfunction should be identified as they are a potential target of prevention or intervention of MCI or dementia.

The Role of the Y Chromosome in Brain Function

In mammals, sex differences are evident in many aspects of brain development, brain function and behaviour. Ultimately, such differences must arise from the differential sex chromosome complements in males and females: males inherit a single X chromosome and a Y chromosome, whilst females inherit two X chromosomes. One possible mechanism for sexual differentiation of the brain is via male-limited expression of genes on the small Y chromosome. Many Y-linked genes have been implicated in the development of the testes, and therefore could theoretically contribute to sexual differentiation of the brain indirectly, through influencing gonadal hormone production. Alternatively, Y-linked genes that are expressed in the brain could directly influence neural masculinisation. The present paper reviews evidence from human genetic studies and animal models for Y-linked effects (both direct and indirect) on neurodevelopment, brain function and behaviour. Besides enhancing our knowledge of the mechanisms underlying mammalian neural sexual differentiation, studies geared towards understanding the role of the Y chromosome in brain function will help to elucidate the molecular basis of sex-biased neuropsychiatric disorders, allowing for more selective sex-specific therapies.