Operating expenses
nm—not meaningful
Research and development expenses
Research and development expenses increased $19.6 million in the year ended March 31, 2019 compared to the year ended March 31, 2018, which was primarily attributable to increases in personnel-related costs of $11.8 million, share-based compensation expense of $3.6 million and information technology and facility costs of $1.6 million.
Research and development expenses for the year ended March 31, 2019 as compared to the year ended March 31, 2018 were positively impacted by approximately $0.5 million primarily as a result of the strengthening of the U.S. dollar relative to the British pound.
Personnel-related cost increased primarily as a result of salaries and benefits associated with increased headcount throughout the year, share-based compensation expense increased primarily as a result of share option grants since the prior year and information technology and facility costs increased primarily as a result of increased headcount.
Sales and marketing expenses
Sales and marketing expenses increased $17.9 million in the year ended March 31, 2019 compared to the year ended March 31, 2018, which was primarily attributable to increases in information technology and facilities costs of $5.3 million, personnel-related costs of $4.0 million, share-based compensation expense of $3.4 million, professional services of $2.7 million, travel and other costs of $1.2 million and marketing costs of $1.1 million.
Sales and marketing expenses for the year ended March 31, 2019 as compared to the year ended March 31, 2018 were positively impacted by approximately $1.5 million primarily as a result of the strengthening of the U.S. dollar relative to the Australian dollar, South African rand and British pound. Information technology and facilities costs and travel and other costs increased primarily as a result of increased headcount.
Personnel-related costs increased primarily as a result of salaries and benefits associated with increased headcount and commissions, partially offset by the impact of adopting ASC 606, which resulted in capitalizing $13.8 million of commissions that would have been expensed under the prior accounting rules. Share-based compensation expense increased primarily as a result of share option grants since the prior year. Professional services costs increased primarily due to increased consulting fees.
General and administrative expenses
General and administrative expenses increased $16.8 million in the year ended March 31, 2019 compared to the year ended March 31, 2018, which was primarily attributable to increases in personnel-related costs of $6.3 million, share-based compensation expense of $5.8 million, information technology and facilities costs of $1.9 million, professional services costs of $1.2 million and litigation-related expenses of $1.0 million. Personnel-related costs increased primarily as a result of salaries and benefits associated with increased headcount.
Share-based compensation expense increased primarily as a result of share option grants since the prior year and to a lesser extent the impact of share option modifications. Information technology and facility costs increased primarily as a result of increased headcount. Professional services costs increased primarily due to acquisition-related expenses.
Restructuring and Impairment of long-lived assets
In the second quarter of fiscal 2019, we recorded a revision to restructuring expense of $0.2 million related to the exit of our Watertown, Massachusetts corporate office space. In the fourth quarter of fiscal 2018, upon the exit of our Watertown, Massachusetts corporate office space, we recorded a restructuring charge of $0.8 million for the remaining non-cancelable rent and estimated operating expenses for the vacated premises, net of sublease rentals and we recorded a non-cash impairment charge of $1.7 million primarily related to leasehold improvements.
Table:
 | Year ended March 31, |  | Period-to-period change | 
 | 2019 | 2018 | Amount   | % Change
 |  |  | (dollars in thousands)  | 
Operating expenses:                 |  |  |  | 
Research and development | $57,939 | $38,373 | $19,566 | 51%
Sales and marketing | 139,194 | 121,246 | 17,948 | 15%
General and administrative | 53,759 | 36,989 | 16,770 | 45%
Impairment of long-lived assets   | — | 1,712 | (1,712) | nm 
Restructuring   | (170) | 832 | (1,002) | nm 
Total operating expenses | $250,722 | $199,152 | $51,570 | 26%


Question: What caused the share-based compensation expense to increase?
Answer: primarily as a result of share option grants since the prior year and to a lesser extent the impact of share option modifications.