The tragic death of Alana Cutland who leapt from a plane in Madagascar after suffering a psychotic incident remains a mystery. Madagascar has mosquitoes carrying cerebral malaria (this nearly always kills) and an anti-malarial drug is pretty much mandatory. At the inquest the police Colonel stated that he had never heard of anti-malarials causing psychosis (probably the same as most UK GPs).
Unfortunately my wife and I can both attest that such drugs do carry a risk of psychosis (Larium in our case). We were fortunate in being able to terminate the drug after just a few weeks but mood swings and trivial arguments nearly terminated our marriage.
Unlike the US this drug is still on the UK approved list, and alternates also have substantial risk factors. If you should ever holiday in East Africa or South East Asia you will be advised to use a suitable anti-malarial – please do so, BUT do research the risks and alternative prophylactics!