Deaths from Alzheimer's Disease in Scotland rose by more than a third in a year, according to official figures.
National Records of Scotland (NRS) said 1,506 people died from all forms of dementia in the second quarter of 2017.
Alzheimer's deaths rose 33.4% compared with the same period a year ago, with deaths from dementia up almost 17%.
Part of the increase came from changes in the way death records are presented, but a charity warned the increase was "alarming".
A total of 570 deaths from Alzheimer's were recorded between March and June 2017 - more than double the 257 deaths that occurred in the same three months of 2014.
Meanwhile, deaths from coronary heart disease fell by 5.3% to 1,590 in the second quarter of 2017.
There was also a slight decrease in cancer deaths, which were down 0.8% to 3,831.
The latest NRS quarterly report on births, deaths and marriages stated: "There has been a relatively large increase in the number of deaths from dementia and Alzheimer's disease with such deaths now accounting for around 10% of all deaths compared to 5% a decade ago."
Dr Matthew Norton, director of policy at Alzheimer's Research UK, said: "Alarming as this report is, we cannot hide away from the reality these statistics represent: the devastating impact of dementia across Scotland.
"Part of the increase has been driven by changes in the way death records are represented in official statistics, but this does not fully account for the size of the increase and we must face up to the fact that dementia is set to become the UK's biggest killer as our population ages."
Scottish Conservative health spokesman Miles Briggs called on ministers to set out what they are doing to tackle the increasing number of Alzheimer's and dementia deaths.
The Tory MSP said: "It seems that gradually the high-profile killers are being reduced, and of course that is to be absolutely welcomed. But they are being replaced by cruel and challenging conditions like Alzheimer's.
"This reveals a major challenge facing Scotland's health and social care system."
Mr Briggs added that the public needed to start seeing signs the government "has a plan".
Mental Health Minister Maureen Watt said: "In line with other countries, the number of people diagnosed with dementia has risen as the population ages and rates of diagnosis have improved.
"Our National Dementia Strategy sets out actions to transform services and improve outcomes for people with dementia, their families and carers to give them the right care, at the right time, in the right setting."