Presenile appearance of abundant Alzheimer's neurofibrillary tangles without senile plaques in the brain in myotonic dystrophy.

In 7 myotonic dystrophy (MyD) cases of 35- to 56-year old and 18 non-neurological age-matched controls paraffin-embedded temporal lobe sections were stained by the modified Bielschowsky method to count neurofibrillary tangles (NFTs) and senile plaques (SPs). In the parahippocampal gyrus, NFTs were observed in all the MyD cases; a few in the youngest, with an increase in number with age to the abundant appearance in the 4 cases in their 50s. The eldest also had many NFTs in the hippocampus. By contrast, the control subjects had, if any, only a few NFTs in the hippocampus and the parahippocampal gyrus. No SPs were observed in any MyD or control case. Thus, it was found that in MyD NFTs appear, unaccompanied by SPs, at an abnormally early age in the parahippocampal gyrus, with a rapid age-related increase in their number. This neuronal change may belong to the progeric features observed in this condition.