thirty adults with parkinson 's disease and 30 neurologically healthy controls individually matched by chronological age ( mean age : 52.03 years , sd = 9.7 ; range from 27 years to 70 years ) , gender ( 19 males and 11 females for both groups , and education ( 6.66% no diploma , 26.6% primary degree,39.9% secondary degree , and 26.66% undergraduate and higher ) participated in this cross - sectional study .
the pd patients were selected based on sample availability from neurology clinic of tehran university of medical sciences hospitals and were diagnosed by a neurologist .
the severity of the disease for pd group was assessed with the unified parkinson 's disease rating scale ( updrs ) , and ranged from mild to moderate .
patients with dementia ( scoring under the recommended cutoff point of 23 on the mmse)(14 ) , patients who were illiterate , and those with other neurological disorders such as cva or history of epilepsy , psychiatric disorder ( depression ) based on medical files and neurologist assessment were excluded .
in the current study , verbal fluency test included semantic fluency task and phonemic fluency tasks .
onsemantic fluency tasks , participants were asked to name as many animals and fruits as possible .
on phonemic tasks , subjects were allowed to generate as many words as possible that began with each of the letters / a/ , /f /and /s/. both tasks were time limited to 60 s of word generation .
responses were recorded on an audio tape for later analysis . repeated words or words with similar suffix were not counted .
the total verbal fluency score was obtained by counting the total number of words . the independent t - test
thirty adults with parkinson 's disease and 30 neurologically healthy controls individually matched by chronological age ( mean age : 52.03 years , sd = 9.7 ; range from 27 years to 70 years ) , gender ( 19 males and 11 females for both groups , and education ( 6.66% no diploma , 26.6% primary degree,39.9% secondary degree , and 26.66% undergraduate and higher ) participated in this cross - sectional study .
the pd patients were selected based on sample availability from neurology clinic of tehran university of medical sciences hospitals and were diagnosed by a neurologist .
the severity of the disease for pd group was assessed with the unified parkinson 's disease rating scale ( updrs ) , and ranged from mild to moderate .
patients with dementia ( scoring under the recommended cutoff point of 23 on the mmse)(14 ) , patients who were illiterate , and those with other neurological disorders such as cva or history of epilepsy , psychiatric disorder ( depression ) based on medical files and neurologist assessment were excluded .
in the current study , verbal fluency test included semantic fluency task and phonemic fluency tasks .
onsemantic fluency tasks , participants were asked to name as many animals and fruits as possible .
on phonemic tasks , subjects were allowed to generate as many words as possible that began with each of the letters / a/ , /f /and /s/. both tasks were time limited to 60 s of word generation .
responses were recorded on an audio tape for later analysis . repeated words or words with similar suffix were not counted . for each task , the total numbers of correct words were determined .
the total verbal fluency score was obtained by counting the total number of words . the independent t - test
the means and standard deviations for letter fluency and semantic fluency were demonstrated in table 1 .
overall , participants in both groups generated more words in the semantic fluency task than in the phonemic fluency task .
results indicated that normal subjects generated significantly more words in both tasks ( semantic fluency task and letter - fluency task ) than parkinson 's patients ( p < 0.001 ) . 
 
semantic , phonemic and verbal fluency performance in parkinson 's disease ( pd ) and normal control ( nc ) subjects a paired t test indicated significance difference between parkinson 's patients and normal subject in total number of words in verbal fluency task ( p < 0.001).table 1 .
the main objective of this study was to investigate performance of non - demented pd patients on verbal fluency .
our results showed that participants with parkinson 's disease have significant deficits on semantic and phonemic fluency measurement compared to the healthy group .
these results are consistent with several previous studies indicating decline in verbal fluency tasks in parkinson 's patients .
gurd ( 2000 ) reported parkinson 's patients have difficulty in semantic and phonemic fluency ( 10 ) .
however , auriacombe et al . ( 1993 ) found that pd patients did not differ from normal group in phonemic fluency ( 12 ) .
in contrast , ivory et al.(3 ) reported no significant difference between pd patients and normal subjects in verbal fluency .
1986 ) found that pd patients generated more words than control group on this task(12 ) .
the difference found in results of different studies may be due to the differences in the investigated languages , as the frequencies of words that start with a particular letter vary between languages .
1998 ) reported that spanish subjects produced fewer words than vietnamese participants , and this discrepancy might be due to differences in their languages because animal names in vietnamese are one - syllable words whereas most animal names in spanish are multisyllabic(15 ) .
the results of the present study that pd demonstrate deficit in verbal fluency could be viewed as consistent with language impairment in pd .
crosson ( 1985 ) reported that basal ganglia damage could affect language formulation by their connections with the cortex(5 ) .
verbal fluency not only evaluates semantic and phoneme knowledge of lexical memory by searching specifics emanticor phonemes class , but subjects should also be able to track previous responses and prevent activation of other categories by executive skills . therefore , verbal fluency deficit in pd patients undoubtedly represents executive dysfunction .
higginson et al ( 2003 ) reported that working memory and verbal fluency correlated with executive functions ( 16 ) .
( 1992 ) have also suggested that poor performance in semantic fluency in these patients is associated with a specific deficit in semantic memory , whilst raskin et al .
( 2009 ) suggested that this problem is caused by a deficit in semantic retrieval and the ability to register , store intact(17 , 18 ) .
( 2012 ) reported that basal ganglia structures are associated with verbal fluency ( 19 ) .
however , a number of neuroimaging studies reported that left prefrontal cortex and subcortical regions correlate with verbal fluency ( 20 , 21 ) . on the other hand , there is much evidence of frontal dysfunction in parkinson patients ( 17 ) . based on this reasoning ,
further studies are needed to investigate a possible relation between verbal fluency deficits with subcortical lesions in pd . in summary
assessing language and executive function by verbal fluency test and early intervention may be effective .
conclusion a high proportion of patients with mde also had a sub threshold hypomania or mania .
findings suggest that bipolar features are more frequent than symptoms indicated by dsm - iv - tr , and exclusion criteria of mood disorders in this classification should be revised .
dsm - iv classification appears to be too narrow or rigid to distinguish amore subtle and  softer  form of bipolar cases from pure unipolar cases .
first , we did not assess the possible age - related changes in the cognitive and language abilities in our patients , although the previous research reported that aging does not affect the phonemic fluency .
second limitation of the present study was that we were unable to match patients for duration and the time course of their disease , although we attempted to control the severity of parkinson in patients group according to unified parkinson 's disease rating scale .
future efforts will be directed toward investigation of the time course of change in verbal fluency performance in pd .
the present study revealsa significant deficit in non - demented pd that supports findings from previous studies .
the deficit in verbal fluency in pd might be associated with cognitive impairment ( executive and memory ) and complex language disorders in pd .
furthermore , a recent cross - sectional study on a small group of pd patients demonstrated that tests of memory , language processing and cognitive function are important in early stage in this group .
neuropsychologists and speech  language pathologists now routinely assess language and cognitive abilities of pd , and the data presented here illustrates the importance of developing neuropsychological instruments that are sensitive to cognitive deficit .
finally , further research using functional brain imaging during verbal fluency tasks is necessary to evaluate the pathology underlying the verbal fluency deficit in pd .
 objectivewhile parkinson 's disease ( pd ) has traditionally been defined by motor symptoms , many researches have indicated that mild cognitive impairment is common in non - demented pd patients . 
 the purpose of this study was to compare verbal fluency performance in non - demented parkinson 's disease patients with healthy controls.methodin this cross - sectional study thirty non - demented parkinson 's disease patients and 30 healthy controls , matched by age , gender and education , were compared on verbal fluency performance . 
 verbal fluency was studied with a phonemic fluency task using the letters f , a , and s , a semantic fluency task using the categories animals and fruits . 
 the independent t - test was used for data analysis.resultsoverall , participants generated more words in the semantic fluency task than in the phonemic fluency task . 
 results revealed significant differences between patients and controls in semantic fluency task ( p<.05 ) . 
 in addition , pd patients showed a significant reduction of correctly generated words in letter fluency task . 
 the total number of words produced was also significantly lower in the pd group ( p<.05).conclusionverbal fluency disruption is implied in non - demented pd patients in association with incipient cognitive impairment . 
Materials and Methods
Participants
Procedure
Results
Discussion
Limitations
Conclusion