Menopause and cognitive impairment: A narrative review of current knowledge

A severe impairment of cognitive function characterizes dementia. Mild cognitive impairment represents a transition between normal cognition and dementia. The frequency of cognitive changes is higher in women than in men. Based on this fact, hormonal factors likely contribute to cognitive decline. In this sense, cognitive complaints are more common near menopause, a phase marked by a decrease in hormone levels, especially estrogen. Additionally, a tendency toward worsened cognitive performance has been reported in women during menopause. Vasomotor symptoms (hot flashes, sweating, and dizziness), vaginal dryness, irritability and forgetfulness are common and associated with a progressive decrease in ovarian function and a subsequent reduction in the serum estrogen concentration. Hormone therapy (HT), based on estrogen with or without progestogen, is the treatment of choice to relieve menopausal symptoms. The studies conducted to date have reported conflicting results regarding the effects of HT on cognition. This article reviews the main aspects of menopause and cognition, including the neuroprotective role of estrogen and the relationship between menopausal symptoms and cognitive function. We present and discuss the findings of the central observational and interventional studies on HT and cognition.

Refinement of chromosome 3p22.3 region and identification of a susceptibility gene for bipolar affective disorder

Genome-wide association studies and meta-analysis, as well as our own previous family-based association results, have pointed to chromosome (ch) 3p22.3 and 3p21.1 as candidate regions to contain a susceptibility gene for bipolar affective disorder (BPAD). In the present study, we further refined the region of interest on ch 3p22.3. We genotyped 94 SNPs within the candidate region in 74 families and performed family-based association analysis using a transmission disequilibrium test. One single SNP (rs166508) was associated with the BPAD phenotype (P = 0.0187). This SNP is located within intron 15 of the integrin alpha 9 (ITGA9) gene. ITGA9 encodes the α9 subunit of the α9β1 integrin, a membrane glycoprotein receptor for neurotrophins, such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). Quantification of ITGA9 transcripts in the peripheral blood of patients with BPAD and controls showed an upregulation of ITGA9 (Kruskal-Wallis P = 0.0339) in patients with the disease-associated genotype (rs166508*A/A), compared to those with rs166508*G/G and rs166508*G/A genotypes. Sequencing of the ITGA9 cDNA revealed a sequence variant (r.1689_1839del) in rs166508*A carriers, which leads to loss of the entire exon 16. In silico analysis revealed that the deleted region contains three putative microRNA binding sites, which may be involved in the negative regulation of ITGA9. In conclusion, our results confirm previous evidence pointing to a candidate region for BPAD on ch 3p.22.3. In addition, we suggest a molecular substrate that could explain the increase of ITGA9 mRNA levels in probands with BPAD, proposing a new mechanism that could be involved in the genetic susceptibility to the disease.