Comparisons of cognitive deterioration rates by dementia subtype

Pathophysiological aspects of dementia and its rate of cognitive deterioration could be dependent on disease subtype, Alzheimer's dementia (AD), vascular dementia (VaD), and Parkinson's disease with dementia (PDD). 150 patients diagnosed at the Chungnam National University Hospital (87 women and 63 men) memory clinic. The participants consisted of 68 patients with AD, 23 patients with VaD, and 59 patients with PDD, who were diagnosed by the individual criteria, respectively. Cognitive screening was evaluated using the Korean version of the mini-mental state examination (MMSE). Repeated evaluations were conducted at 6-month, 1 year, and 2 years after initial baseline assessment. Rates of cognitive decline were calculated by dividing MMSE score differences by the number of months lapsed. No difference was found between the three dementia subtypes with respect to baseline MMSE scores. Cognitive decline was not obvious up to 6-month of the follow-up, but by 12-month of follow-ups was significant regardless of the dementia subtype. Furthermore, the rate of cognitive decline in the AD group was significantly faster than in the PDD or VaD groups. This study suggests that rate of cognitive deterioration in dementia is not linear over time and that dementia subtypes have different rates of cognitive deterioration.