In the context of neurodegeneration and aging, the cerebellum is an enigma. Genetic markers of cellular aging in cerebellum accumulate more slowly than in the rest of the brain, and it generates unknown factors that may slow or even reverse neurodegenerative pathology in animal models of Alzheimer’s Disease (AD). Cerebellum shows increased activity in early AD and Parkinson’s disease (PD), suggesting a compensatory function that may mitigate early symptoms of neurodegenerative pathophysiology. Perhaps most notably, different parts of the brain accumulate neuropathological markers of AD in a recognized progression and generally, cerebellum is the last brain region to do so. Taken together, these data suggest that cerebellum may be resistant to certain neurodegenerative mechanisms.

On the other hand, in some contexts of accelerated neurodegeneration, such as that seen in chronic traumatic encephalopathy (CTE) following repeated traumatic brain injury (TBI), the cerebellum appears to be one of the most susceptible brain regions to injury and one of the first to exhibit signs of pathology. Cerebellar pathology in neurodegenerative disorders is strongly associated with cognitive dysfunction. In neurodegenerative or neurological disorders associated with cerebellar pathology, such as spinocerebellar ataxia, cerebellar cortical atrophy, and essential tremor, rates of cognitive dysfunction, dementia and neuropsychiatric symptoms increase. When the cerebellum shows AD pathology, such as in familial AD, it is associated with earlier onset and greater severity of disease. These data suggest that when neurodegenerative processes are active in the cerebellum, it may contribute to pathological behavioral outcomes.

The cerebellum is well known for comparing internal representations of information with observed outcomes and providing real-time feedback to cortical regions, a critical function that is disturbed in neuropsychiatric disorders such as intellectual disability, schizophrenia, dementia, and autism, and required for cognitive domains such as working memory. While cerebellum has reciprocal connections with non-motor brain regions and likely plays a role in complex, goal-directed behaviors, it has proven difficult to establish what it does mechanistically to modulate these behaviors. Due to this lack of understanding, it’s not surprising to see the cerebellum reflexively dismissed or even ignored in basic and translational neuropsychiatric literature.

The overarching goals of this review are to answer the following questions from primary literature: When the cerebellum is affected by pathology, is it associated with decreased cognitive function? When it is intact, does it play a compensatory or protective role in maintaining cognitive function? Are there theoretical frameworks for understanding the role of cerebellum in cognition, and perhaps, illnesses characterized by cognitive dysfunction? Understanding the role of the cognitive cerebellum in neurodegenerative diseases has the potential to offer insight into origins of cognitive deficits in other neuropsychiatric disorders, which are often underappreciated, poorly understood, and not often treated.

在神经变性和衰老的背景下，小脑是一个谜。小脑细胞衰老的遗传标志物比大脑其他部位的积累速度更慢，并且它会生成未知的因子，这些因子可能会减缓甚至逆转阿尔茨海默氏病（AD）动物模型中的神经退行性病变。小脑显示出早期AD和帕金森氏病（PD）的活动增加，提示其代偿功能可能减轻神经退行性病理生理学的早期症状。也许最值得注意的是，大脑的不同部分在公认的进展中积累了AD的神经病理标记，通常，小脑是最后一个这样做的大脑区域。综上所述，这些数据表明小脑可能对某些神经退行性机制有抗性。

另一方面，在加速神经变性的某些情况下，例如在反复创伤性脑损伤（TBI）后在慢性创伤性脑病（CTE）中看到的情况，小脑似乎是最容易受到损伤的大脑区域之一，也是其中一个首先表现出病理迹象。神经退行性疾病的小脑病理与认知功能障碍密切相关。在与小脑病理相关的神经退行性或神经系统疾病中，例如脊髓小脑共济失调，小脑皮质萎缩和原发性震颤，认知功能障碍，痴呆症和神经精神病症状的发生率增加。当小脑表现出AD病理时，例如在家族性AD中，它与疾病的早期发作和严重程度有关。

小脑以将信息的内部表示与观察到的结果进行比较并向皮层区域提供实时反馈而闻名，皮层区域是一种关键功能，在智力障碍，精神分裂症，痴呆和自闭症等神经精神疾病中受到干扰，并且是认知领域所必需的例如工作记忆。虽然小脑与非运动性大脑区域具有相互联系，并可能在复杂的，目标导向的行为中发挥作用，但事实证明，很难确定其机械调节这些行为的方式。由于缺乏了解，因此在基本的和翻译的神经精神病学文献中看到小脑被反省或什至被忽略就不足为奇了。

这篇综述的总体目标是回答来自主要文献的以下问题：当小脑受到病理影响时，它与认知功能下降有关吗？当它完好无损时，它在维持认知功能中起补偿或保护作用吗？是否存在理论框架来理解小脑在认知中的作用，也许还可以理解以认知功能障碍为特征的疾病？了解认知小脑在神经退行性疾病中的作用，有可能提供对其他神经精神疾病的认知缺陷起源的洞察力，这些疾病通常未被充分认识，了解甚少并且不经常得到治疗。