Parnetti L, Lowenthal D T, Presciutti O, Pelliccioli G P, Palumbo R, Gobbi G, Chiarini P, Palumbo B, Tarducci R, Senin U
Sezione di Gerontologia e Geriatria, Università di Perugia, Italy.
J Am Geriatr Soc. 1996 Feb;44(2):133-8. doi: 10.1111/j.1532-5415.1996.tb02428.x.
To better understand how to differentiate the "in vivo" normal aging brain from pathological conditions, namely dementia of the Alzheimer type (DAT), by means of magnetic resonance imaging (MRI), single photon emission computerized tomography (SPECT), and proton magnetic resonance spectroscopy (1H-MRS), to show neuroanatomical, perfusional and neurochemical details, respectively.
1H-MRS, MRI-based hippocampal volumetry and 99mTc-HMPAO SPECT were performed in healthy older subjects as well as patients suffering from age-associated memory impairment (AAMI) and dementia of Alzheimer type (DAT).
Eighteen subjects were selected from those referred to an outpatient clinic for diagnostic evaluation of cognitive impairment entered the study. Six patients fulfilled NINCDS-ADRDA diagnostic criteria for DAT, six subjects were affected by AAMI, and six cognitively healthy subjects, selected from among relatives of the patients, were defined as controls.
The 1H-MRS and MRI studies were performed on a 1.5 Tesla NMR-imaging system equipped with a spectroscopy research package. SPECT scans were performed on a Gamma 11 computer system.
1H-MRS showed significantly lower N-acetylasparatate concentration in DAT and AAMI compared with controls. Conversely, mean inositol concentration was significantly higher in DAT than in controls, whereas AAMI subjects registered intermediate values. MRI measurements showed significantly reduced volumes of hippocampal formations in DAT and AAMI groups compared with controls. Finally, 99mTc-HMPAO SPECT showed a significant frontal, temporo-parietal, and occipital hypoperfusion in DAT patients only.
These findings support the hypothesis of a continuum among the three conditions studied, or at least between AAMI and DAT, where AAMI seems to be an early, monosymptomatic stage of Alzheimer disease. Accepting this view, it would be questionable to maintain the term "age-associated memory impairment" as a discrete entity.
通过磁共振成像（MRI）、单光子发射计算机断层扫描（SPECT）和质子磁共振波谱（1H-MRS），更好地了解如何将“体内”正常衰老大脑与病理状况（即阿尔茨海默型痴呆（DAT））区分开来，分别展示神经解剖学、灌注和神经化学细节。
对健康老年受试者以及患有年龄相关性记忆障碍（AAMI）和阿尔茨海默型痴呆（DAT）的患者进行1H-MRS、基于MRI的海马体积测量和99mTc-HMPAO SPECT检查。
从前往门诊进行认知障碍诊断评估的受试者中选取18名进入研究。6名患者符合DAT的NINCDS-ADRDA诊断标准，6名受试者患有AAMI，从患者亲属中选取的6名认知健康受试者被定义为对照组。
1H-MRS和MRI研究在配备波谱研究包的1.5特斯拉核磁共振成像系统上进行。SPECT扫描在Gamma 11计算机系统上进行。
与对照组相比，1H-MRS显示DAT和AAMI中的N-乙酰天门冬氨酸浓度显著降低。相反，DAT中的平均肌醇浓度显著高于对照组，而AAMI受试者的肌醇浓度值处于中间水平。MRI测量显示，与对照组相比，DAT和AAMI组的海马结构体积显著减小。最后，99mTc-HMPAO SPECT仅显示DAT患者存在明显的额叶、颞顶叶和枕叶灌注不足。
这些发现支持了所研究的三种状况之间存在连续性的假设，或者至少在AAMI和DAT之间存在连续性，其中AAMI似乎是阿尔茨海默病的早期单症状阶段。接受这一观点后，将“年龄相关性记忆障碍”作为一个独立实体保留是否合理就值得怀疑了。
