What is the cerebellum?
The cerebellum sits below the larger cerebrum of the brain, and is connected via the brainstem. The cerebellum is divided into two hemispheres separated dorsally by a midline zone called the vermis. It contains three primary lobes, the flocculonodular lobe, anterior lobe, and posterior lobe. Broadly, the cerebellum is thought to function in fine motor control (coordination and precision) and motor learning, balance, posture, as well as some cognitive and emotional capacity. The interaction of sensory, cognitive and motor functions may also contribute to proprioception (the awareness of self in space), planning movements, and evaluating information for action. The detailed functions of each region of the cerebellum are determined largely by their connectivity.
What is the evidence for cerebellum alterations?
Moderate quality evidence found grey matter reductions in the bilateral cerebellum of people with schizophrenia, particularly in medication-naïve patients, compared to controls. There were also white matter reductions in the bilateral cortico-ponto-cerebellum tract, and in the bilateral inferior and superior cerebellar penduculus. High quality evidence found no
Moderate to high quality evidence found better overall functioning was associated with larger cerebellum volume, and moderate to low quality evidence found reduced white matter volume in the cerebellum was associated with increased severity of neurological soft signs.
Moderate to high quality evidence found decreased functional activity in the right cerebellum (lobule VIII and crus I) and the left cerebellum (lobule IX), with no increases in functional activity. Functional connectivity strength was decreased in the left cerebellum (lobule IV/V) extending to the left fusiform gyrus (BA 30), and increased in the left cerebellum (crus I/II) of medication-naïve patients with first-episode schizophrenia compared to controls. Moderate to low quality evidence found increased activity in the cerebellum during auditory hallucinations in people with schizophrenia.
Moderate quality evidence found decreased functional activity in the left cerebellum of people with schizophrenia (vs. controls) during episodic memory retrieval. There was reduced activity in the right cerebellum lobule VI during explicit threat processing, and decreased activity in the fusiform gyrus extending into the cerebellum lobule IV/VI during implicit threat processing. There was decreased activity in the cerebellum during reward anticipation tasks. There was increased activity in the cerebellum during facial emotion recognition. Moderate to low quality evidence found decreased functional activity in the cerebellum of first- degree relatives of people with schizophrenia (compared to controls) during working memory and executive functioning, but not during cognitive control, long-term memory, or language processing.
Moderate quality evidence found decreased metabolic N-acetyl aspartate in the cerebellum of people with schizophrenia compared to controls.
Structural and functional changes
Moderate quality evidence found increased grey matter volume and decreased functional activity in the left cerebellum, and increased grey matter volume and increased functional activity in the left cerebellum lobule IX.
Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.