Keilp J G, Prohovnik I
Department of Brain Imaging, New York State Psychiatric Institute, New York 10032, USA.
J Nucl Med. 1995 Aug;36(8):1347-54.
The pathophysiology of Alzheimer's disease may be reflected more in an individual's decline from premorbid levels of functioning than in current measures of absolute severity. To test this hypothesis, we computed an index of intellectual decline for individual patients and examined its relationship to Alzheimer's disease-related functional brain abnormalities.
We studied 27 patients with Alzheimer's disease diagnosed by ADRDA-NINCDS criteria. We used patient demographics and published formulas to construct estimates of premorbid Wechsler Adult Intelligence Scale (WAIS-R) IQs for each subject in the sample and used a current IQ assessment to estimate the decline in IQ that occurred during the disease for each subject. Cortical perfusion was quantified by the planar 133Xe regional cerebral blood flow (rCBF) technique. The characteristic abnormality in parietal cortex was expressed by the parietal index (PI).
Over the estimated disease duration of 3.8 +/- 2.2 yr, the full-scaled IQ declined by an estimated 28.0 +/- 15.5 points. The current PI was in turn well correlated with the IQ decline (r = 0.66; p < 0.001). This association was linear and stronger than those with other, more common measures of current severity. A multiple stepwise regression analysis suggested that IQ decline alone accounted for the variance in PI related to clinical deterioration. Actual images showed a mild blood flow deficit in patients with the smallest estimated IQ declines but deep and extensive lesions in patients with large declines.
These results suggest that the decline from the premorbid baseline, rather than current level of functioning, best predicts the extent of brain damage reflected in the rCBF abnormality, a finding independent of demographic variance.
阿尔茨海默病的病理生理学可能更多地反映在个体从病前功能水平的下降上，而非当前绝对严重程度的测量指标。为了验证这一假设，我们计算了个体患者的智力衰退指数，并研究了其与阿尔茨海默病相关的功能性脑异常之间的关系。
我们研究了27例根据ADRDA-NINCDS标准诊断为阿尔茨海默病的患者。我们利用患者的人口统计学资料和已发表的公式来构建样本中每个受试者病前韦氏成人智力量表（WAIS-R）智商的估计值，并使用当前的智商评估来估计每个受试者在疾病期间发生的智商下降。通过平面133Xe局部脑血流量（rCBF）技术对皮质灌注进行量化。顶叶皮质的特征性异常用顶叶指数（PI）表示。
在估计的3.8±2.2年的疾病持续时间内，全量表智商估计下降了28.0±15.5分。当前的PI又与智商下降密切相关（r = 0.66；p < 0.001）。这种关联是线性的，且比与当前严重程度的其他更常见测量指标的关联更强。多元逐步回归分析表明，仅智商下降就解释了与临床恶化相关的PI方差。实际图像显示，估计智商下降最小的患者有轻度血流不足，但下降较大的患者有深部和广泛的病变。
这些结果表明，从病前基线的下降，而非当前的功能水平，最能预测rCBF异常所反映的脑损伤程度，这一发现独立于人口统计学差异。
