The pathological process that result in subcortical dementia shows neuronal changes that involve primarily the thalamus, basal ganglia, and rostral brain-stem nuclei and mostly, some projections in the white matter from these regions to the cortex, with relative sparing of the cerebral cortex. It affects arousal, attention, mood, motivation, language, memory, abstraction, social skills (especially empathy), extrapyramidal functions, and visuospatial skills. Additionally, damage to the basal forebrain can cause amnesia and psychotic disorders. Controversy
One of the problems with the concept of subcortical dementia is the fact that name implies that it is due to lesions confined to subcortical structures. Anatomically none of the neurodegenerative dementias are strictly cortical or subcortical. In fact, there is invariably an overlap of both cortical and subcortical neuronal changes in both types. History
Charcot described dementia as a feature in Parkinsons disease. McHugh introduced the concept of subcortical dementia.Mayeux and Stern and their colleagues and Tierney and coworkers have been critical of the concept of subcortical dementia. Examples
Progressive supranuclear palsy (chronic acetogenin poisoning)
Atypical Parkinsonism
Binswanger disease (and other forms of vascular dementia)
Corticobasal degeneration
Huntington disease
Multiple system atrophy
HIV-associated neurocognitive disorder (HAND)
HIV-associated dementia


== References ==
The loss of blood volume is detected by cells in the kidneys and triggers thirst for both water and salt via the renin-angiotensin system. Renin-angiotensin system
Hypovolemia leads to activation of the renin angiotensin system (RAS) and is detected by cells in the kidney. When these cells detect decreased blood flow due to the low volume they secrete an enzyme called renin. Renin then enters the blood where it catalyzes a protein called angiotensinogen to angiotensin I. Angiotensin I is then almost immediately converted by an enzyme already present in the blood to the active form of the protein, angiotensin II. Angiotensin II then travels in the blood until it reaches the posterior pituitary gland and the adrenal cortex, where it causes a cascade effect of hormones that cause the kidneys to retain water and sodium, increasing blood pressure. It is also responsible for the initiation of drinking behavior and salt appetite via the subfornical organ. Others
Arterial baroreceptors sense a decreased arterial pressure, and signal to the central nervous system in the area postrema and nucleus tractus solitarii. Cardiopulmonary receptors sense a decreased blood volume, and signal to area postrema and nucleus tractus solitarii. Cellular dehydration and osmoreceptor stimulation
Osmometric thirst occurs when the solute concentration of the interstitial fluid increases. This increase draws water out of the cells, and they shrink in volume.