Young Onset Dementia in New South Wales, Australia in 1891: What has Changed Since Then?

Objectives: This study aimed to determine the prevalence and types of young onset dementia (YOD) in New South Wales (NSW), Australia, in 1891 with comparisons to 21st century estimates. Changes might inform future service planning for persons with YOD.
Methods: Medical case books of two Hospitals for the Insane were examined at the State Archives and clinical and sociodemographic information extracted of persons who were under the age of 65 in April 1891, when a NSW Census occurred, and were given a dementia diagnosis or had symptoms consistent with dementia. Consensus 21st century 'probable' and 'possible' all cause dementia and major neurocognitive disorder diagnoses were determined by two psychiatrists. Prevalence estimates of moderate-severe dementia were determined and compared with 21st century estimates and dementia types.
Results: Of 161 potential dementia cases, 123 were given a consensus 'probable' dementia diagnosis, 28 a 'possible' dementia diagnosis, and ten were given a non-dementia diagnosis, with 'all cause dementia' and 'major neurocognitive disorder' diagnoses identical. Most dementia cases were male (n = 119, 78.8%). 'Unspecified dementia' was the most frequent diagnosis (n = 47, 31.1%), followed by dementia secondary to syphilis (n = 35, 23.2%), epileptic dementia (n = 30, 19.9%), alcohol-related dementia (n = 17, 11.3%), and mixed dementia (n = 16, 10.6%). Epileptic dementia had the youngest average age of admission (34.9 years). Other than epileptic dementia, all other dementia types were more frequent in males. Prominent clinical symptoms included neurological signs (n = 79, 52.3%), psychosis (n = 77, 51.0%), agitation (n = 75, 49.7%), and aggression (n = 45, 29.8%). Most dementia cases either died in hospital (n = 79, 52.3%) or were transferred to a long stay hospital (n = 57, 37.7%). The estimated point prevalence of YOD in persons aged 30-59 in 1891 (86 per 100,000) was higher than current Australian and global estimates in this age group due to the high rates in males (126 per 100,000), but in those aged 60-64, the prevalence in 1891 (159 per 100,000) was much lower than current estimates.
Conclusions: This first examination of YOD in the nineteenth century found high rates of dementia in those under the age of 60 compared with current estimates, particularly in men aged between 30 and 59 years old, and largely due to syphilis, alcohol and epilepsy, conditions that are now treatable and thus demonstrating the potential of effective treatments for YOD.
(© 2024 The Author(s). International Journal of Geriatric Psychiatry published by John Wiley & Sons Ltd.)