You never saw Poirot checking his news feed.
And for good reason (other than that it didn't exist).
A new study has found a link between using the social network Facebook, and the famed 'little grey cells' in your brain.
A study published in Behavioural Brain Research in April 2017 has found that people who frequently check Facebook on their smart phone have less 'grey matter' in the part of the brain's 'nucleus accumbens', thought to be its reward centre.
The reward centre is believed to play a big role in addiction.
They found that there were smaller grey matter volumes in the reward centre when a participant used Facebook frequently.
Participants were recruited from the University of Bonn, and were therefore mainly students.
Their Facebook use was described 'not excessive' by the study.
Using MRI brain scans of 46 men and 39 women, scientists from the Universities of Ulm, Bonn, and Chendu monitored the participant's use of social media over five weeks.
Christian Montag, a researcher at Ulm University, and the corresponding author for the study, told PsyPost:
We were able to demonstrate that the nucleus accumbens, a central region of the SEEKING system — others call it the reward system — plays an important role in understanding Facebook usage on smartphones,
In short, the lower the grey matter volume in this area, the higher Facebook usage/frequency could be observed.
Checking Facebook was compared to other reward seeking activities, meaning we log on looking for a buzz.
The study, which is being presented for peer review, does not conclude if high Facebook use causes there to be less grey matter, or less grey matter prompts higher Facebook use.
Before linking Facebook use to addictive behaviour, the authors recommended a further study into people who use Facebook an excessive amount.