The cognitive (executive) ability of patients with
Parkinson's-disease (PD) deteriorates gradually during the progression of the disease. Fluency of speech, word finding, working memory, ability to plan the future and flexibility decline. Cognitive disturbance was found to be proportional with the speech, posture, gait and balance problems and can not be influenced by
L-dopa substitution. Apart the dorsal and ventral mesolimbic dopaminergic systems the coerulo-cortical noradrenergic, serotoninergic and
cholinergic systems are also impaired in PD. Subcortical
dementia in PD can also be explained by the functional disability of dorsolateral and anterior cingular circuits. Attention deficit can be explained by the
dopamine depletion of cingular cortex. Cortical Lewy bodies, neurofibrillary tangles, neurit plaques and additional vascular pathology should also play a role in
cognitive impairment of PD. In several systemic degenerative diseases associating with Parkinson's syndrome (PS) i.e.
progressive supranuclear palsy (PSP),
corticobasal degeneration (CBD),
multiple system atrophy (MSA)
dementia can be detected with various severity, therefore the question arises concerning the correlation between cognitive disability and PS. Parkinson syndrome can also develop in
frontotemporal dementias (FTD),
Alzheimer's disease and
cortical Lewy body disease (CLBD) but no correlation exists between motor disability and severity of
dementia. In CLBD
dementia can be the initial symptom in 18% of cases but PS can also preceeds the
dementia. In PSP profound depletion of other monoaminergic
neurotransmitter system was also reported. In FTDs associated with PS degeneration of substantia nigra, locus coeruleus and basal nucleus of Meynert has been reported with increased number of neurofibrillary tangles. In patients with vascular PS (VP) there is generally no
tremor and rigidity, but
pseudobulbar palsy,
dementia, gate disturbance, incontinency appears;
L-dopa treatment is generally ineffective. In VP no cellular loss can be found within the substantia nigra, but
leukoaraiosis, lacunae in the white matter and basal ganglia are commonly demonstrated.