Migration is often seen in terms of the impact on western countries.
But losing the young and talented has big consequences for the economies and education systems of countries left behind. In Lithuania it means universities, the launchpads of innovation, can struggle to find enough applicants.
In the 25 years since the fall of Communism, Lithuania has lost one in five of its population.
When it broke away from the old Soviet Union in 1990, the Baltic state had a population of 3.7 million. Now it is down to 2.9 million.
High levels of migration since joining the European Union in 2004 are partly responsible, with European Union statistics showing that almost 54,000 people left in 2011 - half of them heading to the UK.
Adding to Lithuania's population decline is the halving of the birth rate between 1991 and 2004.
The result is a lack of 19 and 20 year olds, hurting the country's universities and endangering efforts to build a knowledge economy.
Student enrolments are dropping by between 5% and 7% per year, says Ilona Kazlauskaite, head of Lithuania's higher education programmes unit at the Education Exchanges Support Foundation.
"The worst predictions are that the number of graduates will fall by 40% by 2023 compared to 2009 if nothing is done."
Pressure on the country's universities is also fuelled by a brain drain of young talent, particularly after the global economic recession.
Unesco's Global Flow of Tertiary-level Students shows more than 12,000 Lithuanians studying abroad out of a student population of 160,000. That's one in every 14 students.
The UK is by far their favourite destination with just under 5,000 Lithuanian students, according to Unesco. A further 1,600 are in Danish universities, where tuition is free for all EU students.
UK universities have the same pulling power in the other two Baltic states - with 2,200 Latvian students and 1,200 from Estonia.
All this causes a strain back in Lithuania where the economy is recovering after the painful austerity years and businesses are crying out for young people with the right skills.
This year began with Lithuania joining the euro and its President Dalia Grybauskaite likes to point out that despite shrinking the economy by 15% after the 2008 financial crash: "Lithuania managed without any bailouts."
The hope in Lithuania is that investment and deeper integration with the west will follow.
So can brighter economic fortunes reverse the human talent flow and attract more international students to Lithuania?
It won't be easy. Even the capital's Vilnius University, dating back to 1597, is struggling.
Competition from foreign universities for the best Lithuanian students is fierce, with scholarships and free tuition dangled in front of the brightest.
Nijole Bulotaite, the university's spokeswoman, admits: "Retaining talent is one of our most pressing problems along with demographic changes."
But the fightback is underway and Lithuania is working with Latvia and Estonia to promote studying in the Baltic states to international students.
Lithuanian data shows that the country hosted almost 5,000 foreign students in 2014 - up from almost 4,000 in 2012.
Many are from Belarus and Russia; however growth markets include Ukraine, Nigeria, Azerbaijan, Georgia and Germany. Students coming from India have risen from just 57 in 2012 to 357 last year.
Ilona Kazlauskaite says: "Medicine and engineering are most popular for foreigners and more degrees are being offered in English."
Exchanges and joint study programmes with universities abroad are opening up Lithuania to students from further afield, including Turkey and South Korea.
However the key may be a new law easing the right for foreign students to stay and look for work for six months after graduation.
Ms Kazlauskaite said this should make Lithuania more attractive to international students. Previously they had to leave after graduating and apply for a new visa, even if they were going on to a master's degree.
Karina Ufert, a Vilnius graduate who chaired the European Students Union in 2012-13, welcomes the move.
"Lithuania's labour market needs international students who have studied here, learnt the language, and want to work here or set up a business," she says.
But more needs to be done to strengthen the universities - with greater focus on rebuilding Lithuania's strengths in science and engineering, says Dr Margarita Starkeviciute, a former member of the European Parliament.
She led round table discussions on the future of Lithuanian higher education in 2013, which called for mergers to create stronger university brands.
Despite support from some university leaders and the vice-minister for education and sciences, Rimantas Vaitkus, there has only been one merger, between a university of medicine and a veterinary academy. Lithuania still has 14 state universities.
Dr Vaitkus says: "Despite falling student numbers, more government money is going into higher education and better co-operation between universities is being encouraged to foster possible mergers."
He also welcomes efforts to reverse the brain drain and support "brain gain" by encouraging Lithuanians working abroad to return on a short-term basis to teach at Lithuanian universities.
"The ratio of brain drain and brain gain depends on the economic situation and now we're part of the euro we hope more of our graduates will come back and find jobs in Lithuania."
This is big challenge for Lithuania and many other Baltic, central and eastern European nations.
But there are some signs of a return.
Marius Skuodis, aged 29, moved to the UK with his wife, Rita, an accountant, for a two-year master of public administration degree at the London School of Economics in 2010.
Now he is back in Vilnius working as a senior specialist in the Bank of Lithuania's international relations department.
"The choice to return was quite difficult," he says. It meant a lower salary in the short term, but the chance to pursue a PhD at Vilnius University and better job opportunities in the long term.
"Lithuania offered me career opportunities I could not expect in the UK," he says.