Influence of Testosterone depletion on Neurotrophin-4 in Hippocampal synaptic plasticity and its effects on learning and memory

Cognitive effects of long-term androgen deprivation therapy in older men with prostate cancer

OBJECTIVE

Androgen deprivation therapy (ADT) is a common treatment for prostate cancer (PCa), with increasing numbers of men on ADT for longer. Limited evidence suggests ADT impacts cognition. This study addressed gaps in the literature by focusing on older men with PCa and assessing ADT usage longer than 1 year.

METHODS

This study of 133 men ≥65 years of age with PCa included two groups: (1) men on ADT for 1-3 years (ADT-exposed), and (2) a comparison group of men with PCa not on ADT (ADT-unexposed). Group comparisons on individual neuropsychological test scores are reported, as well as effect sizes (Cohen's d).

RESULTS

Half (n = 67) of the sample was ADT-exposed and half (n = 66) were unexposed. The average age was 72 years, most were White, and over 50% had at least secondary education. There were no statistically significant differences between groups by age, race, or education. Unadjusted analyses showed the ADT-exposed group, compared with the ADT-unexposed group, performed significantly lower in domains of verbal learning (d = 0.45-0.52, p = 0.01 to <0.01), verbal recall (d = 0.33-0.54, p = 0.06 to <0.01), and possible effects in visuospatial construction (d = 0.33, p = 0.08 to 0.06). When controlling for age and education, similar patterns emerged. The ADT exposed-group performed significantly lower in domains of verbal learning (d = 0.45-0.52, p = 0.06 to 0.03) and verbal recall (d = 0.33-0.54, p = 0.11 to 0.03), and possible effects in visuospatial construction d = 0.33, p = 0.18 to 0.13.

CONCLUSIONS

This study suggests long-term ADT exposure impacts verbal learning, verbal recall, and possibly visuospatial abilities in older men (≥65) with PCa. The potential cognitive effects of ADT should be discussed with older patients considering long-term use of ADT.

Androgen Deprivation Therapy for Prostate Cancer: Focus on Cognitive Function and Mood

Prostate cancer is the second leading cause of cancer death in men in the United States. Androgen deprivation therapy (ADT) is currently the primary treatment for metastatic prostate cancer, and some studies have shown that the use of anti-androgen drugs is related to a reduction in cognitive function, mood changes, diminished quality of life, dementia, and possibly Alzheimer's disease. ADT has potential physiological effects such as a reduction in white matter integrity and a negative impact on hypothalamic functions due to the lowering of testosterone levels or the blockade of downstream androgen receptor signaling by first- and second-generation anti-androgen drugs. A comparative analysis of prostate cancer patients undergoing ADT and Alzheimer patients identified over 30 shared genes, illustrating common ground for the mechanistic underpinning of the symptomatology. The purpose of this review was to investigate the effects of ADT on cognitive function, mood, and quality of life, as well as to analyze the relationship between ADT and Alzheimer's disease. The evaluation of prostate cancer patient cognitive ability via neurocognitive testing is described. Future studies should further explore the connection among cognitive deficits, mood disturbances, and the physiological changes that occur when hormonal balance is altered.

Testosterone Influence on Microtubule-Associated Proteins and Spine Density in Hippocampus: Implications on Learning and Memory

The thorny protrusions or spines increase the neuronal surface area, facilitate synaptic interconnections among neurons, and play an essential role in the hippocampus. Increasing evidence suggests that testosterone, the gonadal hormone, plays an important role in neurogenesis and synaptic plasticity. The role of testosterone on microtubule-associated proteins on dendritic neurite stability in the hippocampus and its impact on learning disability is not elucidated. Adult male Wistar albino rats were randomly selected for the control, castrated, castrated + testosterone, and control + testosterone groups. Bilateral orchidectomy was done, and the testosterone propionate was administered during the entire trial period, i.e., 14 days. The learning assessments were done using working/reference memory versions of the 8-arm radial maze and hippocampal tissues processed for histological and protein expressions. There were reduced expressions of microtubule-associated protein 2 (MAP2), postsynaptic density protein 95 (PSD95), and androgen receptor (AR) and increased expression of pTau in the castrated group. Conversely, the expression of MAP2, PSD95, and AR was increased, and the pTau expression was reduced in the hippocampus of the castrated rat administrated with testosterone. Androgen-depleted rats showed impaired synaptic plasticity in the hippocampus associated with contracted microtubule dynamics. Along with learning disability, there was an increased number of reference memory errors and working memory errors in castrated rats. Observations suggest that androgen regulates expression of neural tissue-specific MAPs and plays a vital role in hippocampus synaptic plasticity and that a similar mechanism may underlie neurological disorders in aging and hypogonadal men.