MEN’S brain shrink rise and fall in volume as hormones ebb and flow throughout the day, a study suggests.
A study that scanned a 26-year-old’s brain 40 times over 30 days indicated that men’s brains shrink by 8pm before resetting overnight.
Researchers from the University of California, Santa Barbara, say this cycle of growing and shrinking coincides with rising and falling levels of steroid hormones: testosterone, cortisol and estradiol.
Study co-author Laura Pritschet – now a postdoctoral scholar in psychiatry at the University of Pennsylvania Perelman School of Medicine – said: “Males show this 70 per cent decrease from morning to night in steroid hormones.
“You can think of it almost like a pulsating rhythm from morning to night,” she told Live Science.
Women’s hormones also fluctuate daily but it’s not as pronounced, as the menstrual cycle simultaneously drives longer-term shifts in hormones, she noted.
Researchers scanned a man’s brain in the morning and evening for a month.
The study, published in The Journal of Neuroscience, found that his overall brain volume decreased throughout the day, as did the thickness of the cortex, the brain’s outermost layer.
The volume of grey matter – which plays a significant role in mental functions, memory, emotions and movement – fell by an average of about 0.6 per cent by each night, researchers found.
Two regions of the cortex, the occipital and parietal cortices, shrank the most. These are involved in visual and sensory processing.
Deeper brain structures, such as the the cerebellum, brainstem and parts of the hippocampus, also saw changes throughout the day.
These parts of the brain are involved in coordinating movement, relaying information between the brain and body, and storing memories.
Though changes in brain structure coincided with the daily ebb and flow of steroid hormones, researchers aren’t yet sure if the hormones are driving the changes.
Study co-author Elle Murata, a doctoral student in psychology and brain sciences at UCSB, told Live Science: “I’m convinced that hormones impact the brain and brain structure.
“But in this study, we can’t say that it’s directly causing it.”
But she said “this is another example debunking the myth that hormones are only relevant for females”.
It comes after separate UCSB research found that ‘pregnancy brain’ is a thing – with scans showing how the brain undergoes a “metamorphosis” in the process of having a baby that lingers years afterwards.
Previous studies have also found that taking hormone replacement therapy (HRT) – which tops up waning levels of oestrogen and progesterone during menopause – can prevent the brain from shrinking as you age and could prevent memory decline over time.
For the more recent UCSB study on men’s brains, the 26-year-old participant underwent brain scans and blood tests every 12 to 24 hours for 30 consecutive days.
At each session, he completed a questionnaire to assess levels of stress, sleep, and his mood.
Source: https://www.the-sun.com/health/12518825/mens-brains-shrink-everyday-reset-overnight-hormones/#