アルツハイマー型老年痴呆の神経病理学的診断に関する研究

Study on the Neuropathological Diagnosis of Senile Dementia of the Alzheimer Type

　本研究は臨床データを伏せて病理学的にアルツハイマー型老年痴呆（SDAT）を疑うという非日常的な方法をとった。同一施設の連続剖検例について他の疾患を除外してから，1）側頭葉吻側内側部皮質の層状神経細胞脱落，2）多数の老人斑やアルツハイマー原線維変化の出現，という条件を設定し，病理学的にSDATが疑える106例を抽出した。その結果，前者を満たす46例（第1群）の臨床診断との一致率が93％に対して，後者のみを満足する60例（第II群）の一致率は25％と非常に低かった。また一致率の高い第1群で条件2を満たす症例は50％前後で，老年性変化の量と分布のみでSDATを疑うには不十分であった。しかし，条件1の導入により全体の一致率は72％に上昇した。また，SDATの病理では側頭葉吻側内側部の病変が非常に重要で，同部位と乳頭体を含む標本が病理学的スクリーニングとして極めて有用であった。

Trying to define more suitable criteria for neuro-pathological diagnosis of senile dementia of theAlzheimer type (SDAT), the three histopath-ological criteria were tentatively made : 1) Laminar neuronal loss in the parahippocampus and medial gyri of the oral temporal lobe, 2) Appea-rance of senile plaques (SPs) and neurofibrillary tangles (NFTs) in the cerebral cortex more than the 95th percentile value of the age-matched control which were obtained from 12 different gyri of the 135 non-demented brains (60 to 106 years old), 3) Exclusion of the other diseases.

There were 106 cases which satisfied the 3rd criterion in 581 consecutive autopsy cases of our hospital. They were divided into two groups. The first group was fulfilled the 1st criterion (46 cases),although approximately a half of the cases did not fulfilled the 2nd criterion. The second group was satisfied the 3rd criterion (60 cases) . The first group included 43 cases clinically diagnosed as SDAT (93 %), which occupied 72 % of the all clinical SDAT cases. On the contrary, only 25 % of the second cases were clinically diagnosed as SDAT.

This study showed that laminar neuronal loss in the oral parahippocampus and medial gyri of the oral temporal lobe of both sides was the most impor-tant criterion for neuropathological diagnosis as well as widespread appearance of many SPs and NFTs in the cerebral cortex.