Hypothalamus and Alzheimer's disease

What is it about?

Autonomic dysfunction has been frequently reported in AD either as hyperactivity or as failure of the autonomic system . The autonomic responses to emotional or cognitive stimuli may be impaired, even in the initial stages of AD. Hypothalamic nuclei may be implicated in AD, although all of them are not involved simultaneously and in the same extend. Microinflammation of the hypothalamus on the other hand may occur in aging and age related diseases such as AD . In the field of clinical investigation was noticed that substance P and hypocretin (orexin), which plays an important role in sleep-wake cycle and food intake, were elevated in the CSF in a substantial number of AD patients in comparison with normal controls . Somatostatin (SST) is consistently reduced in the hypothalamus and neocortical areas in AD, correlating with cognitive decline, although it is well documented that the SST system is also implicated in stress, anxiety and depression

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Why is it important?

Neuropathological studies based on silver impregnation techniques in association with the Golgi - Nissl method, revealed marked dendritic alterations. Loss of dendritic spines, abnormal spines, a considerable decrease in spine density, and substantial decrease in the neuronal population in the hypothalamic nuclei in AD, affecting primarily the suprachiasmatic nucleus (SCN). Electron microscopy revealed marked mitochondrial alterations in the soma and dendritic branches and fragmentation of Golgi apparatus in a substantial number of neurons of the SCN and PVNof the hypothalamus. Among the hypothalamic nuclei the SCN seems to be more seriously affected in aging and in a dramatic way in AD [18,20], a fact that might explain the phenomenon of desynchronization of circadian rhythms (CRs) in the majority of the patients who suffer from AD, since SCN is of substantial importance for the generation and the synchronization of CRs in man.

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