Fluoride toxicity is a burgeoning problem worldwide and also in Rajasthan in India. In the state of Rajasthan, almost all districts have high fluoride (up to 18.0 ppm) in their drinking/ground water sources and about 11 million of the population [is] at risk. Several clinical and experimental studies have reported that fluoride induces changes in cerebral morphology and biochemistry that affect the neurological function. In the present study, 102 adults male (30.5 ± 9.8 yrs) were selected from the high fluoride region of the eastern regions of the Jaipur (Rajasthan, India), where fluoride content in water is 5.5 ± 1.2 ppm. Moreover, age matched controls (31.8 ±8.7) were selected from the Jaipur district where fluoride content in water was less than 1.5 ppm. The serum fluoride levels and acetylcholinesterase (AChE) were estimated, thereafter, General Health Questionnaire 60 (GHQ60) was used to assess behavioral changes in subject and controls. It [was] observed that, the activity of AChE were found to be significantly (p<0.001) reduced in direct[ correlation] with scoring of GHQ60. On the basis of the results it may be concluded that fluoride exposure promotes the deterioration in sympathetic and parasympathetic neuron as evident by reduced AChE activity and [this] positively correlates with cognitive changes. However, further in depth studies is required for the understanding of pathophysiology of fluoride neurotoxicity and its effect on cognitive decline in adults.