The Promises and Pitfalls of Sex Difference Research

It’s been hypothesised that XXY’s are biological females dressed in male clothing, that being so we ask you keep in mind when reading how an XXY experience might have greater similarity to females than males, of course none of this would be necessary if researches were to include Intersex as a variable. Still comparing the binary sexes is a step in the right direction but should by no means be the final step.

The XXY Project

In 2016 the USA National Institutes of Health (NIH) mandated that all pre-clinical research must include sex as a biological variable (SABV), unless strongly justified otherwise. This has substantially increased attention to sex differences research, with good reason. Studying how biological sex contributes to our health can help understanding of disease etiology, manifestation, progression, and treatment. Indeed, males are more likely to be diagnosed with autism spectrum disorders or develop Parkinson’s disease whereas females are more likely to be diagnosed with major depressive disorder, anxiety disorders, autoimmune disease, and multiple sclerosis.

Sex differences are also noted in specific disease subsets, thus more females than males display the relapsing-remitting type of multiple sclerosis than men. Similarly, whereas the incidence of epilepsy is higher in males than females, only women are susceptible to a catamenial epilepsy, where seizures are tied to the menstrual cycle, and up to 70% of females with epilepsy show a variant of catamenial type. Perhaps less well known, there are also sex differences in the timing or onset of neuropsychiatric disorders. Onset of obsessive compulsive disorder is more likely to occur in early adolescence for males but during the perinatal period for females.

Even when prevalence of disease shows no sex bias, such as in schizophrenia, there can be profound differences in timing onset. Males are more likely to present with schizophrenia as teens, but females are more likely to present a couple of years later than males with a secondary peak in middle-age. Each of these examples gives us important clues on the nature of the disease. Yet, sex differences in onset and prevalence are rarely explored despite that studying these sex differences could yield powerful clinical and pre-clinical models of disease, and clues to disease etiology and pathology.

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